This PDF file contains the front matter associated with SPIE Proceedings Volume 8565, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Laser ablation may be a promising method for removal of skin lesions, with the potential for better cosmetic outcomes and reduced scarring and infection. An obstacle to implementing laser ablation is that the treatment leaves no tissue for histopathological analysis. Pre-operative and intra-operative mapping of BCCs using confocal microscopy may guide the ablation of the tumor until all tumor is removed. We demonstrate preliminary feasibility of confocal microscopy to guide laser ablation of BCCs in freshly excised tissue from Mohs surgery. A 2940 nm Er:YAG laser provides efficient ablation of tumor with reduced thermal damage to the surrounding tissue.

Reflectance Confocal Microscopic (RCM) imaging of obliquely-oriented optical sections, rather than with traditional z-stacks, shows depth information that more closely mimics the appearance of skin in orthogonal sections of histology. This approach may considerably reduce the amount of data that must be acquired and processed. However, as with z-stacks, purely visual detection of the dermal-epidermal junction (DEJ) in oblique images remains challenging. Here, we have extended our original algorithm for localization of DEJ in z-stacks to oblique images. In addition, we developed an algorithm for detecting wrinkles, which in addition to its intrinsic merit, gives useful information for DEJ detection.

The effects on skin of two commercially available topical creams for the treatment of eczema are quantitatively studied using optical coherence tomography. An archetypal corticosteroid (Betamethasone valerate) is compared with a nonsteroidal anti-inflammatory drug (Tacrolimus monohydrate) via left/right comparisons of the epidermal thickness of volar forearm skin on selected volunteers, at baseline and after 14 days of treatment. In 3 of 4 subjects we confirmed previous observations that corticosteroids produce pronounced physical thinning of the epidermis over timescales of a few weeks. In 3 of 4 subjects we further found that Tacrolimus produced no change in epidermal thickness. In one of 4 subjects we found evidence that the epidermis was actually thickened following treatment using Tacrolimus.

A compact and easy-to-handle photocoagulation device was used for inducing an immediate coagulation effect in skin large superficial abrasions, reducing the recovering time and improving the wound healing process. The handheld illumination device consists of a high power LED, emitting in the blue region of the spectrum, mounted in a suitable and ergonomic case, together with power supply, electronics, and batteries. The working principle of the LED-based photocoagulator is a photothermal effect: the blue light is selectively absorbed by the haemoglobin content of the blood and then converted into heat. Here we present an in vivo study performed on animal models. 10 Sprague Dawley rats (Harlan, Italy, weighing 200-250 g) were used to study the wound healing process. On the back of each rat, four large abrasions were mechanically produced: two of them were used as a control, while the other two were treated with the photocoagulator, keeping it at a constant distance (2 mm) from the target, in continuous slow motion (treatment time: tens of seconds). The induced photothermal effect was monitored by an infrared thermocamera in order to avoid accidental thermal damage and to control the temperature dynamics during treatment. Objective observations, histopathological analysis and non-linear microscopy performed in a 8 days follow-up study showed no adverse reactions and no thermal damage in the treated areas and surrounding tissues. Moreover, a faster healing process and a better recovered morphology was evidenced in the treated tissue.

Diffuse reflectance spectra (DRS) of biological samples are commonly measured using an integrating sphere (IS), in which spectrally broad illumination light is multiply scattered and homogenized. The measurement begins by placing a highly reflective white standard against the IS sample opening and collecting the reflected light at the signal output port to account for illumination field. After replacing the white standard with test sample of interest, DRS of the latter is determined as the ratio of the two values at each involved wavelength. However, because test samples are invariably less reflective than the white standard, such a substitution modifies the illumination field inside the IS. This leads to underestimation of the sample’s reflectivity and distortion of measured DRS, which is known as single-beam substitution error (SBSE). Barring the use of much more complex dual-beam experimental setups, involving dedicated IS, literature states that only approximate corrections of SBSE are possible, e.g., by using look-up tables generated with calibrated low-reflectivity standards. We present a practical way to eliminate the SBSE using IS equipped with an additional “reference” output port. Two additional measurements performed at this port (of the white standard and sample, respectively) namely enable an accurate compensation for above described alteration of the illumination field. In addition, we analyze the dependency of SBSE on sample reflectivity and illustrate its impact on measurements of DRS in human skin with a typical IS.

Collagen represents major protein component of the extracellular matrix (ECM), thus its monitoring could be used as an ideal tool for assessing wound healing following therapy. Presently, there is a great need to develop quick, objective, non-destructive method to monitor collagen synthesis during progression of wound healing. The applicability of the Laser induced fluorescence technique towards wound healing monitoring by measuring collagen levels at different stages of the healing progression is the main idea behind the current work. Six to eight weeks old Swiss albino mice with ccircular wounds of 15 mm diameter were illuminated with single exposure of 2 J/cm² from He-Ne laser (632.8 nm; 7 mW power; 4.02 mW/cm² power density) along with un-illuminated and un-wounded controls. Spectroscopic changes were monitored by recording in vivo fluorescence from each animal (under anesthesia) at different post-wounding days (5^th, 10^th, 30^thday) by exciting granulation tissue/skin with 325 nm He-Cd laser. The autofluorescence from the tissue/skin was recorded from four different sites and four spectra were recorded from each site. A total of 2160 spectra were recorded from 45 animals. The in vivo fluorescence studies have shown significant increase (P<0.001) in collagen synthesis upon treatment with optimum laser dose of 2 J/cm² immediately after wounding as compared to un-illuminated control group. It can conclude that in vivo fluorescence measurement is effective in monitoring wound healing and hence could be used over ex vivo method as an objective and non-intrusive method to monitor collagen levels

The healing process of chronic wounds is complex, and the complete pathogenesis is not known. Diagnosis is currently based on visual inspection, biopsies and collection of samples from the wound surface. This is often time consuming, expensive and to some extent subjective procedures. Hyperspectral imaging has been shown to be a promising modality for optical diagnostics. The main objective of this study was to identify a suitable technique for reproducible classification of hyperspectral data from a wound and the surrounding tissue. Two statistical classification methods have been tested and compared to the performance of a dermatologist. Hyperspectral images (400-1000 nm) were collected from patients with venous leg ulcers using a pushbroom-scanning camera (VNIR 1600, Norsk Elektro Optikk AS).Wounds were examined regularly over 4 - 6 weeks. The patients were evaluated by a dermatologist at every appointment. One patient has been selected for presentation in this paper (female, age 53 years). The oxygen saturation of the wound area was determined by wavelength ratio metrics. Spectral angle mapping (SAM) and k-means clustering were used for classification. Automatic extraction of endmember spectra was employed to minimize human interaction. A comparison of the methods shows that k-means clustering is the most stable method over time, and shows the best overlap with the dermatologist’s assessment of the wound border. The results are assumed to be affected by the data preprocessing and chosen endmember extraction algorithm. Results indicate that it is possible to develop an automated method for reliable classification of wounds based on hyperspectral data.

Arthritis is a chronic inflammatory disease that induces potentially damaging and commonly disabling. Various imaging modalities have been used for the evaluation of arthritis. This study aimed to investigate the feasibility of laser speckle contrast image (LSCI) in the evaluation of the severity and early stage of arthritis in animal model. Arthritis was induced on mouse foot and evaluated by a trained expert and the LSCI. The arthritis severity was quantitatively evaluated by speckle index (SI) computed from LSCI. In visual inspection by an expert, it was difficult to evaluate the arthritis because there was no noticeable different between control mouse group (CMG) and arthritis mouse group (AMG) in erythema. However, arthritis was easily evaluated by significant SI different between the CMG and AMG. In addition, the LSCI also successfully evaluated the early stage of arthritis, presenting different SI distribution depending on lesion.

Background and Objective: Spatial Frequency Domain Imaging (SFDI) is a non-contact wide-field optical imaging technology currently being developed to investigate the feasibility of quantitative non-invasive evaluation of burn wound severity in a rat model. Our objective is to determine the potential of SFDI for mapping quantitative changes in spatially resolved tissue oxygen saturation and water concentration may be indicative of burn wound severity, healing, and further complications. In this portion of the investigation, we focus on the development of a rat burn model and the acute response of tissue to burn wounds. Study Design/Materials and Methods: A controlled burn protocol involving a heated brass comb was applied to 6 rats. Imaging was acquired at 17 evenly spaced wavelengths in the near-infrared from 650 to 970 nm. Over the course of the 3 hour post-burn period, we were able to map quantitative changes in spatially resolved chromophores. Burn severities were verified post-experiment using standard H and E histology and optical microscopy. Results/Conclusion: In total, we were able to induce 12 superficial-partial thickness burns, 8 deep-partial thickness burns, and 4 full thickness burns in our rat models. While several tissue chromophores were tracked, we found that changes in oxygen saturation and water concentration to be sensitive indicators of burn severity. Future work will include additional longitudinal studies over a period of days in order to investigate which parameters are correlated to tissue healing.

Normal skin barrier function depends on having a viable epidermis, an epithelial layer formed by keratinocytes. The transparent epidermis, which is less than a 100 mum thick, is nearly impossible to see. Thus, the clinical evaluation of re-epithelialization is difficult, which hinders selecting appropriate therapy for promoting wound healing. An imaging system was developed to evaluate epithelialization by detecting endogenous fluorescence emissions of cellular proliferation over a wide field of view. A custom-made 295 nm ultraviolet (UV) light source was used for excitation. Detection was done by integrating a near-UV camera with sensitivity down to 300 nm, a 12 mm quartz lens with iris and focus lock for the UV regime, and a fluorescence bandpass filter with 340 nm center wavelength. To demonstrate that changes in fluorescence are related to cellular processes, the epithelialization of a skin substitute was monitored in vitro. The skin substitute or construct was made by embedding microscopic live human skin tissue columns, 1 mm in diameter and spaced 1 mm apart, in acellular porcine dermis. Fluorescence emissions clearly delineate the extent of lateral surface migration of keratinocytes and the total surface covered by the new epithelium. The fluorescence image of new epidermis spatially correlates with the corresponding color image. A simple, user-friendly way of imaging the presence of skin epithelium would improve wound care in civilian burns, ulcers and surgeries.

Scarring can lead to significant cosmetic, psychosocial, and functional consequences in patients with hypertrophic scars from burn and trauma injuries. Therefore, quantitative assessment of scar is needed in clinical diagnosis and treatment. The Vancouver Scar Scale (VSS), the accepted clinical scar assessment tool, was introduced in the nineties and relies only on the physician subjective evaluation of skin pliability, height, vascularity, and pigmentation. To date, no entirely objective method has been available for scar assessment. So, there is a continued need for better techniques to monitor patients with scars. We introduce a new spectral imaging system combining out-of-plane Stokes polarimetry, Spatial Frequency Domain Imaging (SFDI), and three-dimensional (3D) reconstruction. The main idea behind this system is to estimate hemoglobin and melanin contents of scar using SFDI technique, roughness and directional anisotropy features with Stokes polarimetry, and height and general shape with 3D reconstruction. Our proposed tool has several advantages compared to current methodologies. First and foremost, it is non-contact and non-invasive and thus can be used at any stage in wound healing without causing harm to the patient. Secondarily, the height, pigmentation, and hemoglobin assessments are co-registered and are based on imaging and not point measurement, allowing for more meaningful interpretation of the data. Finally, the algorithms used in the data analysis are physics based which will be very beneficial in the standardization of the technique. A swine model has also been developed for hypertrophic scarring and an ongoing pre-clinical evaluation of the technique is being conducted.

A few new low invasive fiber laser technologies for treatment of 1) capillary malformations (port-wine stains), 2) venous, arterial, and arteriovenous malformations, 3) lymphatic malformations of 3 types: micro, small and large-cystic lymphangiomas are presented in this work. There were applied 1.56 μm laser distant photocoagulation, 1.56 μm laser endovascular thermotherapy, 1.9 μm laser instant ablation, 1.9 μm laser interstitial thermotherapy, and 1.9 μm laser excision. The technologies were applied to about 300 patients. Good clinical and esthetic results have been achieved in great majority cases.

We report on “eye-safe” erbium glass laser operating at Short-Wave Infra-Red (SWIR) region at 1534nm, to treat Onychomycosis or toenail fungus. Infected toenails of 12 patients were treated over a 3 month period using both long pulse and Q-switched laser output pulses. Our results compared favorably to Neodymium Yittrium Aluminum Garnet (Nd:YAG) laser fungus treatment studies as reported in literature. Nd:YAG laser devices, operating in the Near Infra- Red, (NIR) region at 1064nm, have recently become an effective alternative treatment to traditional oral medications used to treat nail fungal infections. Conventional nail infection treatments employ medications such as allylamines, azoles and other classes of antifungal drugs that are unpopular due to numerous side-affects and drug interactions. Side effects of these drugs include headache, itching, loss of sense of taste, nausea, diarrhea, heart failure and even potential death from liver failure [1,2,3]. The effectiveness of conventional oral antifungal medications varies. In addition, antifungal prescription drugs are administered for long periods ranging from 6 weeks to 18 months. Nd:YAG antifungal laser treatment reports claim high success rates (65-95%) in eradicating toenail fungus and without adverse side-affects. Multiple laser treatments are administered over a 3 to 6 month period [4,5,6,7]. Our initial treatments performed with the Er:glass laser on toenail fungus patients required only 1 to 2 treatments for cure. This same SWIR laser was used in experiments to treat Athlete's Foot fungal infections. The 1534nm Er:glass laser emission has been found to be well optimized for dermatological treatments due high transmission properties of human skin in the SWIR region. Increased depth of tissue penetration is well-tolerated and provides for effective treatment of various skin conditions. [8,9,10,11] “Eye-safe” Class I lasers provide for practical skin and nail tissue treatment without the need for eye-protection goggles. Laser safety filters may inhibit a practitioner’s vision and ability to distinguish skin and nail regions exhibiting different colors and textures. The laser is “eye-safe” due to the fact that Megawatt peak power Q-switched lasers operating at 1.54um in the narrow spectral window between 1.4um and 1.6um are approximately 8000 times more eye-safe than other laser devices operating in the visible and near infrared. Long-pulse or free running lasers operating in this wavelength range are ~ 2000 times more eye-safe [12].

In this paper, we studied the phenylalanine amino acid in different systems, it means, the amino acid with different solvent molecules as water, ammonia and urea, via density functional theory (DFT). These molecules are present in the natural moisturizing factor (NMF) of skin that is found in the stratum corneum. The aim of this study is improving the understanding of the environment role and its influences. Therefore, in this paper we analyzed the vibrational modes (and compared to FT-Raman and FT-IR experimental values) and electronic properties as the charge densities (HOMO and LUMO). We also verified the hydrophobic effect and the dependence of amino acid structure on the quantities of solvent.

This work aimed the development of a discriminating model, using Raman spectroscopy, based on the estimated concentration of biochemical components presented in skin, for in vivo diagnosis. Raman spectra were collected in patients who underwent excision surgery of suspicious lesions at the lesion site and at a normal circumjacent site. It has been estimated the relative amount of selected biochemical compounds presented in skin. The Raman spectra of normal and malignant (basal cell carcinoma - BCC and squamous cell carcinoma - SCC) skin are quite similar, with some spectral differences in the regions of lipids, nucleic acids, and hemoglobin. Some biochemicals showed statistically significant differences among N, BCC and SCC, such as elastin, ceramide, melanin, nucleid acid, actin and phenylalanine. Elastin and ceramide presented significant differences between N and BCC, melanin, DNA and actin presented significant differences between N and BCC and between N and SCC, being melanin and DNA decreased in neoplasias, in contrast with actin, that increased in neoplasias. Concentration of phenylalanine was significantly increased for SCC compared to N and BCC. The relative concentration of melanin, DNA and phenylalanine showed sensitivity, specificity and accuracy of about 81%, 65% and 60%, respectively, using Mahalanobis distance as a discriminator. This model is being incorporated to a Raman system with automated data collection and processing that could be used for a future in vivo, real time discrimination algorithm.

Background: Painful bladder syndrome/interstitial cystitis (PBS/IC) is defined as a syndrome of urgency, frequency, and suprapubic pain in the absence of positive urine culture or obvious bladder pathology. As no specific etiology has been identified yet, no specific methodology exists for diagnosis of this condition. One potential etiology of PBS/IC is inflammation of the bladder mucosa associated with abnormal angiogenesis and ulcerative lesions. The purpose of this study was to examine the feasibility of using transcutaneous near infrared spectroscopy (NIRS) of the bladder to monitor tissue oxygenation and hemodynamics as a means of differentiating subjects diagnosed with PBS/IC from those with other bladder conditions. Methods: Twenty-four adult patients with lower urinary tract dysfunction were divided into 2 groups, PBS/IC and non-PBS/IC after standard diagnostic investigations. Detrusor oxygen saturation percentage (TSI%) was measured in all subjects while they were at rest in a supine position, using a spatially resolved (SR) NIRS instrument. Mean values of detrusor TSI% were significantly different between the two groups (74.2%±4.9 in PBS/IC vs. 63.6%±5.5 in non-PBS/IC, P<0.0005). Results: Noninvasive NIRS interrogation of the bladder demonstrated that patients diagnosed as having PBS/IC had significantly higher detrusor oxygen saturation at rest. Conclusions: SR-NIRS as a feasible non-noninvasive entity for use in the evaluation of patients for the presence or absence of physiologic changes associated with PBS/IC.

The treatment of choice for patients with end-stage renal disease is kidney transplantation. However, acute tubular necrosis (ATN) induced by an ischemic insult (e.g., from prolonged ex vivo storage times, or non-heart beating cadavers) is a major factor limiting the availability of donor kidneys. In addition, ischemic induced ATN is a significant risk factor for eventual graft survival and can be difficult to discern from rejection. Currently, there are no rapid and reliable tests to determine ATN suffered by donor kidneys and whether or not donor kidneys might exhibit delayed graft function. OCT (optical coherence tomography) is a rapidly emerging imaging modality that can function as a type of “optical biopsy”, providing cross-sectional images of tissue morphology in situ and in real-time. In a series of recent clinical trials, we evaluated the ability of OCT to image those features of the renal microstructure that are predictive of ATN. Specifically, we found that OCT could effectively image through the intact human renal capsule and determine the extent of acute tubular necrosis. We also found that Doppler based OCT (i.e., DOCT) revealed renal blood flow dynamics that is also reported to be a determiner of post-transplant renal function. This kind of information will allow transplant surgeons to make the most efficient use of available donor kidneys, eliminate the possible use of bad donor kidneys, provide a measure of expected post-transplant renal function, and allow better distinction between post-transplant immunological rejection and ischemic-induced acute renal failure.

Successful identification of the cavernous nerves (CN’s) during radical prostatectomy requires detection of the CN’s through a thin layer of overlying fascia. This study explores the 1490 nm infrared (IR) diode laser wavelength for rapid and deep subsurface CN stimulation in a rat model, in vivo. A 150-mW, 1490-nm diode laser providing an optical penetration depth of ~ 520 μm was used to stimulate the CN’s in 8 rats through a single mode fiber optic probe with 1-mm-diameter spot and 15 s irradiation time. Successful ONS was judged by an intracavernous pressure response (ICP) in the rat penis. Subsurface ONS at 1490 nm was also compared with previous studies using 1455 and 1550 nm IR diode laser wavelengths. ONS was observed through fascia layers up to 380 μm thick using an incident laser power of ~ 50 mW. ICP response times as short as 4.6 ± 0.2 s were recorded using higher laser powers bust still below the nerve damage threshold. The 1490-nm diode laser represents a compact, low cost, high power, and high quality infrared light source for use in ONS. This wavelength provides deeper optical penetration than 1455 nm and more rapid and efficient nerve stimulation than 1550 nm.

Optical nerve stimulation (ONS) may be useful for intra-operative identification and preservation of the prostate cavernous nerves (CN’s), responsible for erectile function, during radical prostatectomy. ONS relies on a photothermal mechanism of laser-tissue interaction in which elevating nerve temperature to within a narrow range (~ 42 - 47 ^oC) is critical to successful nerve activation without thermal damage. This preliminary study explores a prototype temperature-controlled laser system for maintaining a constant nerve temperature during ONS of the rat prostate CN’s. A 150-mW, 1455-nm diode laser was operated in continuous-wave mode during stimulation of the rat CN’s for 30 s through a fiber optic probe with 1-mm-diameter spot. The all-single-mode ONS system was controlled by a computer which opened and closed an in-line mechanical shutter in response to an IR sensor, with a temperature set-point of 45 ^oC. Thermal camera temperature measurements and ONS without temperature control were performed for comparison. Strong correlation was observed between IR sensor and camera temperatures. With temperature control, CN temperature was maintained at 45.0 ± 1.5 ^oC. Without IR sensor feedback, CN temperatures continued to rise during ONS, reaching unsafe levels of ~ 50 ^oC.

Photo dynamic diagnosis (PDD) is a convenient and well-documented procedure for diagnosis of bladder cancer and tumours using endoscopic techniques. At present, this procedure is available only for routine use in an operating room (OR) and often with substantial photobleaching effects of the photosensitizer. We present a novel optical design of the endoscopic PDD procedure that allows the procedure to be performed in the outpatient department (OPD) and not only in the OR. Thereby, inpatient procedures lasting 1-2 days may be replaced by a few hours lasting procedure in the OPD. Urine blurs the fluorescence during PDD used in the OPD. Urine contains fluorescent metabolites that are excited by blue light giving an opaque green fluorescence confounding the desired red fluorescence (PDD) from the tumour tissue. Measurements from the clinical situation has shown that some systems for PPD based on blue light illumination (PDD mode) and white light illumination used for bladder tumour diagnosis and surgery suffers some inherent disadvantages, i.e., photo bleaching in white light that impairs the possibility for PDD as white light usually is used before the blue light for PDD. Based on spectroscopic observations of urine and the photoactive dye Protoporphyrin IX used in PDD a novel optical system for use with the cystoscope has been devised that solves the problem of green fluorescence from urine. This and the knowledge of photo-bleaching pitfalls in established systems make it possible to perform PDD of bladder tumours in the OPD and to improve PDD in the OR.

Fiber optic attraction of urinary stones during laser lithotripsy has been previously observed, and this phenomenon may potentially be exploited to pull stones inside the urinary tract without mechanical grasping tools, thus saving the urologist valuable time and space in the ureteroscope’s single working channel. In this study, Thulium fiber laser (TFL) high-pulse-rate/low-pulse-energy operation and Holmium:YAG low-pulse-rate/high-pulse-energy operation are compared for fiber optic “suctioning” of Plaster-of-Paris stone phantoms. A TFL with wavelength of 1908 nm, pulse energy of 35 mJ, pulse duration of 500 μs, and pulse rate of 10-350 Hz, and Holmium laser with wavelength of 2120 nm, pulse energy of 35-360 mJ, pulse duration of 300 μs, and pulse rate of 20 Hz were tested using 270-μm-core fibers. A peak “pull” speed of ~ 2.5 mm/s was measured for both TFL (35 mJ and 150-250 Hz) and Holmium laser (210 mJ and 20 Hz). Particle image velocimetry and thermal imaging were used to track water flow for all parameters. Fiber optic suctioning of urinary stone phantoms is feasible for both lasers. However, TFL operation at high-pulse-rates/low-pulse-energies provides faster, smoother stone pulling than Holmium operation at low-pulserates/ high-pulse-energies. After further study, this method may be used to manipulate urinary stones in the clinic.

Q-switched Tm:YAG laser ablation mechanisms on urinary calculi are still unclear to researchers. In this study, dependence of water content in calculus phantom on calculus ablation performance was investigated. White gypsum cement was used as a calculus phantom model. The calculus phantoms were ablated at single pulse and contact mode in three different conditions: dry calculus in air, wet calculus in air, and wet calculus in water. Ablation volume was obtained on average 0.006, 0.008, and 0.008 mm³ in dry calculus in air, wet calculus in air, and wet calculus in water groups, respectively. There were three proposed ablation mechanisms that could explain the effect of water content in calculus phantom on calculus ablation performance, including shock wave due to bubble collapse, spallation, and microexplosion. Shock wave generation due to bubble collapse in wet calculus in water condition had negligible effect on calculus ablation as captured by a needle hydrophone and cannot be a primary mechanism for calculus ablation in this study. Increased absorption coefficient of wet calculus can cause stronger spallation process compared with that caused by dry calculus; and as a result, higher calculus ablation was observed in both wet calculus in air and wet calculus in water. Vaporization of interstitial water in porous calculus phantom can also help enhance calculus ablation efficiency. There were some limitations in this study including use of small sample size and lack of employing real urinary calculus, which should be addressed in future experiment.

The Thulium fiber laser (TFL) has recently been proposed as an alternative to the Holmium:YAG laser for lithotripsy. The TFL’s Gaussian spatial beam profile provides higher power transmission through smaller optical fibers with reduced proximal fiber tip damage, and improved saline irrigation and flexibility through the ureteroscope. However, distal fiber tip damage may still occur during stone fragmentation, resulting in disposal of the entire fiber after the procedure. A novel design for a short, detachable, distal fiber tip that can fit into an ureteroscope’s working channel is proposed. A prototype, twist-lock, spring-loaded mechanism was constructed using micromachining methods, mating a 150-μm-core trunk fiber to 300-μm-core fiber tip. Optical transmission measuring 80% was observed using a 30 mJ pulse energy and 500 μs pulse duration. Ex vivo human calcium oxalate monohydrate urinary stones were vaporized at an average rate of 187 μg/s using 20 Hz modulated 50% duty cycle five pulse packets. The highest stone ablation rates corresponded to highest fiber tip degradation, thus providing motivation for use of detachable and disposable distal fiber tips during lithotripsy. The 1-mm-outer-diameter prototype functioned comparable to previously tested tapered fiber tips, and the novel design shows promise for potential integration into miniaturized flexible ureteroscopes.

OBJECTIVES: We tested the hypothesis that retropulsion varies with stone size. METHODS: Stone phantoms of uniform cube dimensions were constructed and irradiated with Ho:YAG energy (0.5 J - 3.5 J). Displacement was measured. RESULTS: At any given pulse energy, retropulsion decreased as stone size increased, p<0.05. At any given stone size, retropulsion increased as pulse energy increased, p<0.05. CONCLUSIONS: A strategy of low pulse energy at high repetition rate is appropriate for ureteral stones. For larger bladder and renal stones, retropulsion is minimal even with high pulse energies. More study is warranted.

Introduction: Different laser-systems are currently used for stone fragmentation in the upper urinary tract. The aim of our study was to evaluate probe velocity and displacement, retropulsion and fragmentation characteristics two novel devices the electromechanically driven EMS LithoBreaker® (EMS Medical), and of the CO2 cartridge driven LMA StoneBreaker® (Cook Urological) in vitro test models.Testing of the LithoBreaker® included additionally two different cushion guides (harder, softer) to assess the effect of the damper properties on the impulse characteristics. Patients and methods: Maximum probe velocities and displacements were measured using high-speed photography at a resolution of 100.000 frames per second. Repulsion testing was conducted through a 7.5 Fr ureteroscope in an underwater set-up. The probes were projected against a non-frangible led mass placed in a 15 Fr horizontally mounted silicone tube as an in-vitro model of the ureter. Repulsion was determined by measuring the distance the lead mass (0.98g) was displaced. Fragmentation efficiency was assessed by measuring the number of single shots required to break Bego Stone phantoms hard (15:3) and soft (15:6) with an average size of 7.5 mm x 5.5 mm placed on a metal mesh (edge length 3.15mm) into < 3 mm fragments. Mean and standard deviation were computed for all groups and statistical analysis was performed (student’s t-test). Results: The StoneBreaker® yielded the highest velocity of 22.0 ± 1.9 m/sec. followed by the LithoBreaker® assembled with the hard cushion guide of 14.2 ± 0.5 m/sec and the soft probe guide of 11.5 ±0.5 m/sec. accordingly. The maximum probe displacement for the StoneBreaker® was 1.04 mm and for the LithoBreaker® 0.9 mm and 1.1 mm (hard versus soft cushion guide). Repulsion produced using the 1mm probes showed no statistical differences between the devices. Using the 2mm probes, the hardness of the damper used significantly changed the repulsion behaviour of the LithoBreaker®. Using the 1mm probe, the amount of single shots for fragmentation of soft Bego Stones was significantly higher for the LithoBreaker® with soft cushion guide: mean 31.5 ± 11.31 and hard cushion guide: mean 21.5 ± 5.29 compared to the StoneBreaker®: mean 11.2 ± 2.65. Fragmentation efficiency for the hard Bego Stones showed similar statistically significant results. Conclusion: The electromechanic LithoBreaker® and the pneumatic Stonebreaker® were shown to be effective in cracking stone phantoms with relatively low number of pulses. Fragmentation characteristics improved substantially with the higher hardness of the cushion support higher velocity equals higher fragmentation performance of the LithoBreaker®. Repulsion produced were at comparable levels. More testing is required to more detailed information on impulse frequency and capacity for stone clearance time to be used in clinical practice.

Prostate cancer (PCa) is the second most common cancer in US men. Metastasis is the final step of tumor progression and remains the primary cause of PCa death. Hence preclinical, orthotopic models of PCa metastasis are necessary to develop new therapeutics against metastatic disease. Yet unlike irrelevant subcutaneous tumor models, the deployment of orthotopic models of cancer metastasis in drug research and development is limited by the inability to longitudinally monitor cancer progression/regression in response to administration of experimental pharmaceuticals. Recently, a nearinfrared fluorescent protein (iRFP) was created for deeper imaging [1]. Imaging prostate tumor growth and lymph node metastasis in nude mice therefore becomes possible using this new fluorescent gene reporter. In this study, we first developed an intensified CCD (ICCD)-based iRFP fluorescence imaging device. Then human PCa PC3 cell lines expressing iRFP gene reporter were orthotopically implanted in male Nu/Nu mice at 8-10 weeks old. After 6-10 weeks, in vivo, in situ and ex vivo fluorescence imaging was performed. In vivo iRFP fluorescence imaging showed that the detected fluorescence concentrated at the prostate and became stronger over time, indicating the growth of implanted PCa. Fluorescence was non-invasively detected at locations of prostate-draining lymph nodes as early as 5 weeks post implantation, indicating the metastasis to lymph nodes. In situ and ex vivo fluorescence imaging demonstrated that the detected signals from PCa and lymph nodes were correlated with cancer positive status of tissues as assessed through standard pathology.

In recent years, Raman spectroscopy has emerged as a potentially viable tool for automated cancer diagnostics. However, due to the complexity of the signal obtained from a tissue, most of the studies have been confined to statistical analysis of the spectra with principal component analysis being most often reported as the analysis of choice. These types of analyses are sensitive to modification of the Raman spectra due to tissue processing. The study presented here addresses the modifications of the Raman spectra obtained from prostate tissue histopathological slides due to the tissue treatment and its influence on the automated cancer diagnostics via Raman spectroscopy.

Cybesin, a smart contrast agent to target cancer cells, was investigated using a near infrared (NIR) spectral polarization imaging technique for prostate cancer detection. The approach relies on applying a contrast agent that can target cancer cells. Cybesin, as a small ICG-derivative dye-peptide, emit fluorescence between 750 nm and 900 nm, which is in the “tissue optical window”. Cybesin was reported targeting the over-expressed bombesin receptors in cancer cells in animal model and the human prostate cancers over-expressing bombesin receptors. The NIR spectral polarization imaging study reported here demonstrated that Cybesin can be used as a smart optical biomarker and as a prostate cancer receptor targeted contrast agent.

It has been proposed a spectral model to evaluate the biochemical differences between prostate carcinoma and benign fragments using dispersive Raman spectroscopy. We have examined 51 prostate fragments from surgically removed PrCa; each fragment was snap-frozen and stored (-80°C) prior spectral analysis. Raman spectrum was measured using a Raman spectrometer (830 nm excitation) coupled to a fiber-optic probe. Integration time and laser power were set to 50 s and 300 mW, respectively. It has been collected triplicate spectra from each fragment (total 153 spectra). Some samples exhibited a strong fluorescence, which was removed by a 7th order polynomial fitting. It has been developed a spectral model based on the least-squares fitting of the spectra of pure biochemicals (actin, collagen, elastin, carotene, glycogen, phosphatidylcholine, hemoglobin, and water) with the spectra of tissues, where the fitting parameters are the relative contribution of the compounds to the tissue spectrum. The spectra (600-1800 cm^-1 range) are dominated by bands of proteins; it has been found a small difference in the mean spectra of PrCa compared to the benign tissue, mainly in the 1000-1400 cm^-1 region, indicating similar biochemical constitution. The spectral fitting model revealed that elastin and phosphatidylcholine were increased in PrCa, whereas blood and water were reduced in malignant lesions (p < 0.05). A discrimination of PrCa from benign tissue using Mahalanobis distance applied to the contribution of elastin, hemoglobin and phosphatidylcholine resulted in sensitivity of 72% and specificity of 70%.

Gathering vibrational data from the human middle ear is quite difficult. To this date the well-known acoustic probe is used to estimate audiometric parameters, e.g. otoacoustic emissions, wideband reflectance and the measurement of the stapedius reflex. An acoustic probe contains at least one microphone and one loudspeaker. The acoustic parameter determination of the ear canal is essential for the comparability of test-retest measurement situations. Compared to acoustic tubes, the ear canal wall cannot be described as a sound hard boundary. Sound energy is partly absorbed by the ear canal wall. In addition the ear canal features a complex geometric shape (Stinson and Lawton¹). Those conditions are one reason for the inter individual variability in input impedance measurement data of the tympanic membrane. The method of Laser-Doppler-Vibrometry is well described in literature. Using this method, the surface velocity of vibrating bodies can be determined contact-free. Conventional Laser-Doppler-Systems (LDS) for auditory research are mounted on a surgical microscope. Assuming a free line of view to the ear drum, the handling of those laser-systems is complicated. We introduce the concept of a miniaturized vibrometer which is supposed to be applied directly in the ear canal for contact-free measurement of the tympanic membrane surface vibration. The proposed interferometer is based on a Fabry-Perot etalon with a DFB laser diode as light source. The fiber-based Fabry-Perot-interferometer is characterized by a reduced size, compared to e.g. Michelson-, or Mach-Zehnder-Systems. For the determination of the phase difference in the interferometer, a phase generated carrier was used. To fit the sensor head in the ear canal, the required shape of the probe was generated by means of the geometrical data of 70 ear molds. The suggested prototype is built up by a singlemode optical fiber with a GRIN-lens, acting as a fiber collimator. The probe has a diameter of 1.8 mm and a length of 5 mm.

Using data from our previously described otoscope¹ that uses 1310 nm phase-sensitive spectral domain optical coherence tomography (PS-SDOCT), we demonstrate a software technique for improving the signal-to-noise (SNR). This method is a software post-processing algorithm applicable to generic PS-SDOCT data describing phase versus time at a specific depth position. By sub-sampling the time trace and shifting the phase of the subsamples to maximize their correlation, the subsamples can be coherently averaged, which increases the SNR.

Aim: To develop a bilateral vestibulopathy animal model induced by gentamicin using RS rat and to see the effect of LLLT on this bilateral vestibulopathy model. Method: RS rats were divided into 3 groups, control group (C), laser group (L), and histology group (H). All animals in the 3 groups received gentamicin (GM) 110 mg/kg, intravenously once daily for 3 days. The animals underwent sinusoidal oscillation about a vertical axis before the GM injection, 1, 3, and 7 days post injections. Transcanal low level laser therapy (LLLT) was irradiated to left ear canal for 7 days, starting 1 day post the GM injection. The H group animals were irradiated into the left ear of L group for 3 days, starting 1 day post GM injections for 3 days. C and L groups were sacrifice on 9^th day and H group was sacrificed on 7^th day. Results: The gain of the C group was significantly decreased in 3 and 7 days. The gain of the right ear of L group was decreased significantly in 3 and 7 days. The gain of left ear of L group was decreased in 3 days post LLLT but the decreased gain was improved significantly comparing to the level of 7 days gain of right ear and it was much closer to the pre-GM level. The average number of cells in cupula of H group after laser treatment for 3 days was significantly lower in non laser treated right ear comparing to the laser treated left ear and ears of the normal rats. Conclusion: The present study demonstrated that LLLT restores vestibular function and vestibular hair cells in rats post gentamicin induced ototoxic damage. LLLT may have clinical implications in the treatment of various vestibular dysfunction. Further studies are essential to verify the exact mechanisms and the most effective application of LLLT to rescue vestibular dysfunction.

We describe a novel dual-functional optical coherence tomography (OCT) system with both a 3-D OCT real time scanner and a fiber probe using a sapphire ball lens for imaging and sensing the critical structures of the temporal bone. To prevent injury to facial nerve, 3-D visualization links anatomic landmarks to 3-D map of critical intracochlear structures. We used a graphics processing unit to boost the computing and 3-D rendering performance of swept source OCT. Both the intracochlear structures and facial nerve trunk of cadaveric human temporal bones are clearly identified with 3-D OCT volumetric rendering.

A major reason we can perceive faint sounds and communicate in noisy environments is that the outer hair cells of the organ of Corti enhance the sound-evoked motions inside the cochlea. To understand how the organ of Corti works, we have built and tested the phase-sensitive Fourier domain optical coherence tomography (PSFDOCT) system. This system has key advantages over our previous time domain OCT system [1]. The PSFDOCT system has better signal to noise and simultaneously acquires vibration data from all points along the optical-axis [2]. Feasibility of this system to measure in vitro cochlear vibrations in the apex was demonstrated earlier [3]. In this study, we measure the in vivo vibrations of the organ of Corti via round window in live anaesthetized guinea pigs using PSFDOCT. This region of the guinea pig cochlea responds to very high frequencies (10 - 40 kHz). The current vibration noise floor for native organ of Corti tissue is 0.03 nm in this frequency range. Sound-induced vibrations of the stapes, which delivers input to the cochlea, are also measured. The measured vibrations of the organ of Corti demonstrate non-linear compression and active amplification characteristic of sensitive mammalian cochlea.

Objective: To investigate the concordance between optical images obtained with high-resolution microendoscopy (HRME) and conventional histopathology for ex vivo cholesteatoma specimens and surrounding middle ear epithelium. Methods: After resection of cholesteatoma and surrounding middle ear epithelium from surgical patients, tissues were stained with a contrast agent, proflavine, and the HRME fiberoptic scope was placed directly on each tissue specimen. 4- 10 short movie clips were recorded for both the cholesteatoma and surrounding middle ear epithelium specimens. The imaged areas were sent for standard histopathology, and the stained specimens were correlated with the HRME images. IRB approval was obtained, and each patient was consented for the study. Results: Ten cholesteatoma specimens and 9 middle ear specimens were collected from 10 patients. In each case, cholesteatoma was easily discriminated from normal middle ear epithelium by its hyperfluorescence and loss of cellular detail. Qualitative analysis for concordance between HRME images and histological images from the same surgical specimen yielded a strong correlation between imaging modalities. Conclusions: Keratinizing cholesteatoma and surrounding middle ear epithelium have distinct imaging characteristics. Loss of cellular detail and hyperfluorescence with proflavine are the hallmark characteristics of cholesteatoma which allow for differentiation from normal middle ear epithelium. Real-time optical imaging can potentially improve the results of otologic surgery by allowing for extirpation of cholesteatomas while eliminating residual disease. We anticipate performing an in vivo study to test this hypothesis.

The application of photonics to manipulate and stimulate neurons and to study neural networks has gained momentum over the last decade. Two general methods have been used: the genetic expression of light or temperature sensitive ion channels in the plasma membrane of neurons (Optogenetics and Thermogenetics) and the direct stimulation of neurons using infrared radiation (Infrared Neural Stimulation, INS). Both approaches have their strengths and challenges, which are well understood with a profound understanding of the light tissue interaction(s). This paper compares the opportunities of the methods for the use in cochlear prostheses. Ample data are already available on the stimulation of the cochlea with INS. The data show that the stimulation is selective, feasible at rates that would be sufficient to encode acoustic information and may be beneficial over conventional pulsed electrical stimulation. A third approach, using lasers in stress confinement to generate pressure waves and to stimulate the functional cochlea mechanically will also be discussed.

High-speed digital videoendoscopy system is emerging as a new clinical tool for voice assessment. The system can acquire images of the vibrating vocal folds with simultaneous recording of voice data from the patient. The laryngeal image-based analysis has been proven valuable for objective and quantitative assessment of voice kinematics in health and disease, and meanwhile, acoustic analysis of voice data could assist in the study of phonatory characteristics and reveal useful information related to laryngeal pathophysiology. Contrast to the hardware acquisition systems, the development of effective software for handling such massive visual/sound data has lagged behind. In this paper, a software system is designed to process the laryngeal image sequences and perform image-based analyses as well as acoustic analyses. Our software contains following modules: (1) Import and view Module - to read AVI video data and sound data (wave file), edit/compile and save selected data, make image montages using DirectShow technology and display the acoustic waveform using DirectSound technology; (2) Image Process Module – to perform frame-by-frame image segmentation to delineate the glottis, to extract the GAW and bilateral vocal fold displacements; (3) Image Analysis Module – to adopt Nyquist plot displays that involves the Hilbert transform based analysis of GAW, and to provide instantaneous frequency and amplitude distributions; (4) Acoustic Analysis Module – to perform Fast Fourier Transform (FFT) and Spectrogram analyses of the imported sound data, to display the plot of the sound data and provide instantaneous frequency and amplitude distributions and Nyqiust plot and (5) Dual GAW and sound wave display module. Upon rigorous testing of this software using clinical data samples we demonstrate the applications of the software to the study of dynamic characteristics of the glottis, which may correlate with voice quality and health condition.

Acquired subglottic stenosis is a narrowing of the airway caused by prolonged endotracheal intubation. Currently, there are no non-invasive means to diagnose the disease. A previous study by this same group introduced optical coherence tomography (OCT) as a means of monitoring the progression of stenosis. The aim of the current study was to qualitatively and quantitatively analyze OCT images obtained from a subglottic stenosis model of the rabbit airway. 15 rabbits were used throughout the study, and a MEMs based OCT probe was utilized. The OCT images obtained were analyzed using a free software program, 3D Slicer. The region of scarred tissue was grown out and measured quantitatively. This study demonstrated the feasibility of using a program to quantify the progression of scarring in OCT images, in addition to qualitatively correlating between histology, endoscopic, and OCT images. Future works may include utilization of a long-range probe and use of a pressure necrosis model to better emulate the actual onset of neonatal subglottic stenosis.

Divided-pupil line-scanning confocal microscopy (DPLSCM) can provide a simple and low-cost approach for imaging of human tissues with pathology-like nuclear and cellular detail. Using results from a multidimensional numerical model of DPLSCM, we found optimal pupil configurations for improved axial sectioning, as well as control of speckle noise in the case of reflectance imaging. The modeling results guided the design and construction of a simple (10 component) microscope, packaged within the footprint of an iPhone, and capable of cellular resolution. We present the optical design with experimental video-images of in-vivo human tissues.

Late oral radiation toxicity is a common condition occurring in a considerable percentage of head and neck cancer patients after radiation therapy which reduces their quality of life. The current examination of these patients is based on a visual inspection of the surface of the oral cavity; however, it is well known that many of the complications start in the subsurface layers before any superficial manifestation. Considering the currently suboptimal examination techniques, we address this clinical problem by using optical coherence tomography (OCT) to monitor the subsurface oral layers with micron-scale resolution images. A spectral-domain OCT system and a specialized oral imaging probe were designed and built for a clinical study to image late oral radiation toxicity patients. In addition to providing qualitative 2D and 3D images of the subsurface oral layers, quantitative metrics were developed to assess the back-scattering and thickness properties of different layers. Metric derivations are explained and preliminary results from late radiation toxicity patients and healthy volunteers are presented and discussed.

It is generally accepted that oral cancer arises in the presence of oral precancerous lesions. However, the clinical courses of these lesions are quite unpredictable, and a fundamental enigma remains that when and how these lesions turn to malignant growth. Characterization of these potentially malignant lesions is thus important and could serve as early indicators of this neoplastic transformation process, potentially facilitates the treatment outcome and improves the survival rate. Higher harmonic generation microscope (HGM), providing images with a <500nm lateral resolution at a 300μm penetration depth without leaving photodamages in the tissues, was used for this purpose. Oral cavity biopsies were obtained from 18 patients with clinical suspected oral precancerous lesions scheduled for surgical biopsy. HGM images were compared with histological images to determine the results. By visualization of subtle cellular and morphological changes, the preliminary result of this HGM image discloses excellent consistency with traditional histolopathology studies, without the need for fixation, sectioning and staining. More specifically speaking, the keratin thickness was found to be increased comparing with normal adjacent controls. In some cases, variations in cell size, nuclear size and increased nuclear/cytoplasmic ratio, and increased size of nucleoli were identified, indicating different stages of malignant transformation. These results together indicated that HGM provides the capability to characterize features of oral precancerous lesions as well as oral cancer progression, and holds the greatest potential as an ideal tool for clinical screening and surveillance of suspicious oral lesions.

Optical interferometry using Fourier domain OCT (FD-OCT) can image structures using vibration as the contrast mechanism. An A-scan measurement of light reflected from a tissue at a position x,y yields an intensity spectrum, I(λ), which is sequentially acquired over a short time period, 88 ms, to yield 1000 spectra at equally spaced time points, I(λ,t), while an audio frequency of sound pressure is imparted to the tissue to induce vibration. Analysis converts I(λ,t) into displacement Δz(z,t) of tissue structures along the z axis. Fourier analysis converts Δz(t) at each z into a vibration spectrum, and the amplitude of vibration at the driving audio frequency is specified. This process is repeated for each x position at a given y, to yield an image of vibration amplitude, A(z,x) [nm]. Hence, vibration amplitude becomes the contrast mechanism. This method is not a new idea, but a derivative of Doppler OCT. This report simply provides a concise algorithm in MATLAB for students wishing to implement vibration measurements using FD-OCT. An example shows the vibration of the ossicles of the middle ear viewed through the intact tympanic membrane.

Melanoma of the head and neck and its treatment are complex issues. The behavior of head and neck melanoma is aggressive, and it has an overall poorer prognosis than of other skin sites. The goal of this research was to determine if melanoma manipulation could enhance penetration of cancer cells from the primary tumor into the circulatory system. Nude mice were inoculated with melanoma cells in the mouse ear. Blood vessels were monitored for the presence of circulating tumor cells (CTCs) using in vivo photoacoustic (PA) flow cytometry (PAFC). The implanted tumor underwent compression, incisional biopsy, or surgical excision, and the release of CTCs was monitored using in vivo PAFC in real time. We discovered that some medical procedures, like compression of an implanted tumor of a mouse model or an incisional biopsy, may either initiate CTC release in the blood which previously contained no CTCs or dramatically increased (10-30–fold) CTC counts above the initially recorded level. These findings indicate that some intervention (such as palpation during physical exam, or incisional biopsy) can potentially enhance penetration of cancer cells from a primary tumor into the blood circulation, which may increase the risk of metastases. Our results warn oncologists of at least some precaution during physical examination, careful surgery strategy.

Introduction: The need for reduction of post-tonsillectomy hemorrhage has led to promotion of tonsillotomy techniques for tonsil tissue reduction in obstructive tonsillar hypertrophy. A first study compares ablative tissue effects using 1470nm diode laser and CO2-laser for tonsillotomy in an intraindividual design. A number of different laser systems have been used for volume reduction of hyperplastic nasal turbinates. The aim of a 2nd clinical feasibility study was to show the coagulative and tissue reducing effects using a novel Tm: fiber laser system emitting at λ = 1940 nm Patients and methods: First 21 children aged 3 -13 years (mean age 6.3 years) underwent laser tonsillotomy for obstructive tonsillar hypertrophy in this double blind, prospective, randomized, clinical feasibility trial. In each case, tonsillotomy was performed using fibre guided 1470nm diode laser (contact mode, 15 W power) on the one side and CO2-laser (12 W power) on the other side. An independent physician documented clinical presentation and patients’ symptoms preoperatively and on day 1, 3, 7, 14 and 21 postoperatively using standardized questionnaire including VAS (was ist das) for each side separately. The 2^nd clinical feasibility trial included 11 patients suffering from hyperplastic inferior nasal turbinates, who were therapy-refractory to conservative medical treatment. The obstructive nasal cavity was treated using the 1940 nm Tm: fiber laser at < 5 W output power. The treatment was performed in non-contact mode under endoscopic control. Patients ’ symptoms were documented both preoperatively and on days 1 – 3 and 28 postoperatively using a non-validated questionnaire. Additionally, an endoscopic examination was performed. Results: Mean duration of single tonsillotomy operative treatment was 2.7 min using 1470nm laser and 4.9 min using CO2 laser respectively. Intraoperative bleeding and the frequency of bipolar forceps use for intraoperative bleeding control was significantly less pronounced using the 1470nm diode laser system. There was no difference in postoperative pain scores between the CO2-laser treated and the 1470nm fibre guided diode laser treated side. No infections, hemorrhages or other complications occurred in the course of the three weeks postoperative period. In the turbinate study, none of the patients showed infections, and no hemorrhages or other complications occurred intraor postoperatively.The mean laser activation time was extremely short being 28.0 ± 8.5 s. In conjunction with a low power setting (median, 3 W; mean ± standard deviation, 3.3 ± 1.1 W), a low energy of 90.2 ± 37.8 J was applied. A significant reduction in nasal obstruction could be documented in all patients on day 28 postoperatively. Evaluation, as assessed preoperatively and 4 weeks postoperatively, showed significant subjective improvements. Conclusion: A fiber-guided 1470nm diode laser system offers an efficient and safe method for tonsillotomy as treatment of obstructive tonsillar hypertrophy. Compared to our standard practice with CO2- laser, 1470nm laser application provides comparable tissue ablation effects with less intraoperative bleeding and shorter operation time. The treatment of hyperplastic inferior turbinates using a 1940 nm Tm: fiber laser provides sufficient tissue reduction in a short operation time using low total energy. Patients described a significant improvement in nasal breathing postoperatively.

This paper describes the development and implementation of 3 μm lasers for myringotomy and microsurgery. Two different lasers were investigated. The first, an Er-doped, CW zirconate glass fiber laser optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.76 μm with concomitant green incoherent emission that served as a convenient visible illumination beam. The second, a 1 W CW Er:YAG solid-state laser also optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.94 μm, coincident with the strongest infrared water absorption peak. Running CW, both lasers are expected to avoid the loud acoustical shocks associated with pulsed lasers. Myringotomies were carried out with the Er:YAG laser on anaesthetized guinea pigs and the effects of the laser were documented. Laser ablated samples of tympanic membrane, soft tissue and bone were histologically examined. Histology results indicated that the CW Er:YAG laser is a potential candidate for a new myringotomy tool and possibly for otologic microsurgery, but deliverable power levels need to be increased to the 2 W (or higher) level. This work was funded under NIH SBIR Grant No. 5R44DC004899.

Background and Purpose: Combination therapy of interstitial photodynamic therapy (iPDT) with Cetuximab to attain symptomatic control of recurrent head and neck cancer.

Methods: Two patients with Unresectable recurrent Head and Neck SCC were treated with iPDT alone and iPDT and cetuximab. Treatments were administered in an outpatient setting. A single dose of Photofrin at 2 mg per kilogram of body weight was administered intravenously two days prior to laser illumination. The iPDT was accomplished by delivering 630-nm laser light through two laser fibers with 2.5 and 5 cm long diffusive ends. Light irradiance of 400 mW/cm for 250 seconds was used to deliver a total of 100 J/cm, during the iPDT. Light applications were conducted, twice, at 3-4 days interval. One of the patients was treated with cetuximab along with iPDT.

Results: Near total resolution of tumor was observed in the patient treated with iPDT and cetuximab, and partial resolution was seen in the patient treated with iPDT alone.

Conclusion: Interstitial photodynamic therapy may be used to treat patients with recurrent unresectable head and neck cancer. The combination of iPDT with Cetuximab has the potential to improve tumor response in the patient population for whom there is no effective therapies. This observation merits further studies.

In this paper, we conduct a phantom study for modeling the autofluorescence (AF) properties of tissue. A combined optical coherence tomography (OCT) and AF imaging system is proposed to measure the strength of the AF signal in terms of the scattering layer thickness and concentration. The combined AF-OCT system is capable of estimating the AF loss due to scattering in the epithelium using the thickness and scattering concentration calculated from the co-registered OCT images. We define a correction factor to account for scattering losses in the epithelium and calculate a scatteringcorrected AF signal. We believe the scattering-corrected AF will reduce the diagnostic false-positives rate in the early detection of airway lesions due to confounding factors such as increased epithelial thickness and inflammations.

Introduction: A recent ex-vivo study using micro-CT in patients with chronic obstructive pulmonary disease (COPD) showed that narrowing and disappearance of small conducting airways precedes the onset of emphysematous destruction in COPD. Until recently, the airway remodeling process could not be studied in detail in-vivo. In this study, we investigated the repeatability of navigating an Optical Coherence Tomography (OCT) catheter to image the same airways in smokers with and without COPD. Method: OCT imaging was performed by inserting the catheter through a sub-segmental airway to a small bronchiole. Three-dimensional OCT imaging of 5 cm of airway segments was obtained. The catheter was removed and reinsertion into the same airway was attempted. The number of airway generations and quantitative measurements of the airway wall area were investigated. Results: Sixty-three airways in 30 subjects were analyzed. Repeated insertion into the same airway was observed at 53.8 %, 92.3% and 70.8% of the time in the upper, middle and lower lobes respectively. The percentage differences of paired measurements of airway wall area between matched and unmatched airways in bronchioles were 5.8 ± 4.6 % and 7.3 ± 5.4 % respectively Conclusions: Repeated OCT imaging of airways is possible in the majority of cases except in the upper lobes. For airways that are not completely matched, some of the airway segments can still be used for comparison by careful alignment of the airway. OCT may be a useful method to study the remodeling process in small airways and the effect of therapeutic intervention.

Lung cancer is the leading cause of cancer related death. Macroscopic imaging techniques such as computed tomography are highly sensitivity at detecting small, ≤ 2cm, peripheral pulmonary lesions (PPLs) in the lung but lack the specificity necessary for diagnosis. Bronchoscopy is a procedure routinely performed to diagnose PPLs but is hindered with a low diagnostic yield due to challenging lesion localization. We have developed a flexible transbronchial optical frequency domain imaging (TB-OFDI) catheter that functions as a ‘smart needle’ to confirm the needle placement within the target lesion prior to biopsy. The TB-OFDI smart needle consists of a flexible and removable OFDI catheter that operates within a 21-gauge transbronchial needle aspiration (TBNA) needle. The OFDI catheter can be easily removed from the needle to facilitate subsequent aspiration or biopsy acquisition. The OFDI imaging core consists of an angled-polished ball lens with a spot size of 25 μm at a working distance of 160 μm from the catheter sheath. The ball-lens was designed to have an ellipsoid shape in order to compensate for the astigmatism caused by encasing the optics within a protective sheath. Transbronchial imaging of inflated excised swine lung parenchyma with the TB-OFDI smart needle yielded clear images of alveoli. In-vivo transbronchial imaging was also performed on three swine with artificial lesions injected transthoracially. Our results suggest that the TB-OFDI smart needle may be a useful tool for guiding biopsy acquisition to increase the diagnostic yield of PPLs.

We have been investigating ultrahigh resolution optical coherence tomography (UHR-OCT) imaging of lung tissues using fiber based super continuum (SC) sources. The high power, low-noise, Gaussian shaped SC generated with ultrashort pulses and optical fibers at several wavelength regions were used as the broadband light sources for UHROCT. Since the lung consists of tiny alveoli which are separeted by thin wall, the UHR-OCT is supposed to be effective for lung imaging. The normal and diseased lung tissues were observed without invasive procedures to the lung itself. The clear images of alveoli were observed with index matching effect by saline. In this work, we investigated the three-dimensional UHR-OCT imaging of lung structure. The lungs of rats inflated with 10% formalin at 5 cmH₂O, 15 cmH₂O, and 20 cmH₂O pressure were prepared as the sample for investigation of size and shape of the lung structure. These samples were fixed with 10% formalin. The interalveolar septa, thin walls separating the alveoli, were clearly observed. The difference of size and shape of alveoli and thier three-dimensional network was clearly observed from the UHR-OCT images. The clear images of alveoli were observed with index matching effect of 10% formalin. We investigated the wavelength dependence of 3D UHR-OCT image of lung structure at 800 nm, 1060 nm, and 1700 nm wavelength regions. The 3D UHR-OCT images of structure of rat lung were clearly observed in all wavelength regions and wavelength dependence of imaging was discussed.

New optical techniques have the potential to fill the gap between radiological and microscopic approaches to assess the lung's internal structure. Since its quantitative assessment requires unbiased sampling and measurement principles, imaging of the whole lung with sufficient resolution for visualizing details is important. To address this request, we applied scanning laser optical tomography (SLOT) for the three dimensional imaging of mouse lung ex vivo. SLOT is a highly efficient flourescence and transmission microscopy technique allowing for 3D imaging of specimen of sizes up to several millimeters. Previously fixed lung lobes and whole lungs were optically cleared and subsequently imaged with SLOT while making use of intrinsic contrast mechanisms like absorption and autofluorescence. Imaging of airways, blood vessels and parenchyma is demonstrated. Volumetric SLOT datasets of the lung's internal structure can be analyzed in any preferred planar orientation. Moreover, the sample preparation preserves microscopic structure of the lung and allows for subsequent correlative histologic studies. In summary, SLOT is a useful technique to visualize and survey the internal structure of mouse lung at different scales and with various contrast mechanisms. Potential applications of SLOT in lung research are e.g. quantitative phenotype analysis of mouse models of human lung disease in combination with stereological methods.

Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), currently affects roughly one-third of the world’s population. Drug resistant strains of Mtb decrease the effectiveness of current therapeutics and demand the development of new antimicrobial therapies. In addition, the current vaccine, Bacille Calmette Guérin (BCG), has variable efficacy for disease prevention in different populations. Animal studies are often limited by the need to sacrifice at discrete time points for pathology and tissue homogenization, which greatly reduces spatial and temporal resolution. Optical imaging offers the potential for a minimally-invasive solution to imaging on a macroscopic and microscopic scale, allowing for high resolution study of infection. We have integrated a fluorescence microendoscope into a whole-animal optical imaging system, allowing for simultaneous microscopic and macroscopic imaging of tdTomato expressing BCG in vivo. A 535 nm LED was collimated and launched into a 10,000 element fiber bundle with an outer diameter of 0.66 mm. The fiber bundle can be inserted through an intra-tracheal catheter into the lung of a mouse. Fluorescence emission can either be (1) collected by the bundle and imaged onto the surface of a CCD camera for localized detection or (2) the fluorescence can be imaged by the whole animal imaging system providing macroscopic information. Results from internal localized excitation and external whole body detection indicate the potential for imaging bacterial infections down to 100 colony forming units. This novel imaging technique has the potential to allow for functional studies, enhancing the ability to assess new therapeutic agents.

The development of real-time, label-free imaging techniques has recently attracted research interest for in situ differentiation of cancerous lesions from normal tissues. Molecule-specific intrinsic contrast can arise from label-free imaging techniques such as Coherent Anti-Stokes Raman Scattering (CARS), Two-Photon Excited AutoFluorescence (TPEAF), and Second Harmonic Generation (SHG), which, in combination, would hold the promise of a powerful label-free tool for cancer diagnosis. Among cancer-related deaths, lung carcinoma is the leading cause for both sexes. Although early treatment can increase the survival rate dramatically, lesion detection and precise diagnosis at an early stage is unusual due to its asymptomatic nature and limitations of current diagnostic techniques that make screening difficult. We investigated the potential of using multimodality nonlinear optical microscopy that incorporates CARS, TPEAF, and SHG techniques for differentiation of lung cancer from normal tissue. Cancerous and non-cancerous lung tissue samples from patients were imaged using CARS, TPEAF, and SHG techniques for comparison. These images showed good pathology correlation with hematoxylin and eosin (H and E) stained sections from the same tissue samples. Ongoing work includes imaging at various penetration depths to show three-dimensional morphologies of tumor cell nuclei using CARS, elastin using TPEAF, and collagen using SHG and developing classification algorithms for quantitative feature extraction to enable lung cancer diagnosis. Our results indicate that via real-time morphology analyses, a multimodality nonlinear optical imaging platform potentially offers a powerful minimally-invasive way to differentiate cancer lesions from surrounding non-tumor tissues in vivo for clinical applications.

Intravascular near-infrared fluorescence (NIRF) imaging is a new approach for characterizing the physiological features of atherosclerotic plaque, but random catheter positioning within the vessel results in non-quantitative measurements due to light attenuation through variable distances through blood. We hypothesized that the construction of a combined NIRF-intravascular ultrasound (IVUS) catheter would enable tracking of the catheter position within the blood vessel and permit corrections to NIRF measurements taken at variable distances from the vessel wall. In this study, a combined NIRF-IVUS catheter was designed, co-registered NIRF and IVUS data was acquired in vessel phantoms and ex vivo arteries, depth-dependent attenuation of the fluorescent signal was corrected by an analytical light propagation model. Average root-mean-square error between NIRF estimates of fluorophore concentrations and known concentrations of fluorescent targets in coronary artery phantoms improved from 94.9% to 16.2% following NIRF corrections. We demonstrate that catheter-to-vessel wall distances derived from IVUS imaging can be employed to correct for inaccuracies caused by random NIRF catheter sensing distances.

Recently, Optical Coherence Tomography (OCT) has become one of the preferred clinical techniques for intracoronary diagnostic imaging. Thanks to its high resolution imaging capability, the OCT technique allows to identify microscopic features associated with various types of coronary plaque and to track of stent position, malaposition and neo-intimal tissue growth after stent implantation. Accurate visualization of stent struts can help to examine the status of implanted stents potentially leading to proper treatment of the coronary artery disease. However, unfortunately, current stent identification involves time-consuming segmentation algorithms sometimes requiring labor-intensive manual analysis process. To resolve the problem, we propose a high-speed automatic segmentation algorithm of intravascular stent struts in OCT images. Unlike the other "automatic" stent segmentation algorithms, which are mainly based on time-consuming machine learning algorithms with manual addition and removal of stent struts for correction during the analysis process, our algorithm does not require any manual adjustments of stent struts. Our algorithm first analyzes 10 consecutive crosssectional OCT images to take boundary information into account to enhance the accuracy of guide-wire segmentation and lumen segmentation. Then, it performs stent segmentation by automatically eliminating guide-wire signals using the previous segmentation results. The implementation of our algorithm uses the Intel(R) IPP library on CPU and the CUDA technology on GPU, which achieves the average analysis time of 0.28 s/frame and the detection rate ranging from 84% to 88.6% for about 120 continuous images per patient. As such, the proposed algorithm is robust and fast enough to be integrated in clinical routine.

Effect of catheter eccentricity on the appearance of stent struts in IV-OCT images in presence of thick neointimas was examined by simulation of light-stent interaction. A phantom blood vessel was constructed from a mix of polydimethylsiloxane (PDMS) and titanium dioxide to simulate the elastic and optical scattering properties of the arterial wall. A Cordis CYPHER^® sirolimus-eluting stent was deployed within the phantom vessel and high resolution Micro-CT images of the stent strut were recorded to create a three-dimensional representation. Simulation of IV-OCT catheter and reflection of light from the stent strut and neointima was implemented for different catheter eccentricities. An optical model of the IV-OCT catheter was constructed and IV-OCT images corresponding to rotation of the light beam over the stent strut were simulated. The measured parameters included intensity and optical path length of light reflecting from the stent strut and coupled into catheter. The results indicate that in presence of thick neointimas sunflower effect is not observed and neointimal thickness measurement using IV-OCT is consistent with true values irrespective of catheter eccentricity.

Purpose: Neoatherosclerosis within a stent has been recently described as a culprit of late stent failure. We investigated by optical coherence tomography (OCT) the association of neoatherosclerotic plaque morphology with neointimal rupture (NR) and clinical presentation in patients late after coronary stent implantation. Methods: From 1/1/2007 to 31/1/2012, 74 patients from two institutions underwent OCT assessment of a coronary stent implanted at least 18 months prior to OCT study. Native atherosclerosis criteria were used for neointimal characterization. Results: Neoatherosclerosis was observed in 59.5% of the stents (n=44). Stents with neoatherosclerosis were more often associated with symptoms compared to stents without neoatherosclerosis (59.1% acute coronary syndrome (ACS), 25% stable angina (SA), and 15.9% asymptomatic versus 43.3% ACS, 6.7% SA, 50% asymptomatic, p<0.01). Among neoatherosclerotic lesions (n=44), NR was detected in 19 (43.2%) and had higher incidence in ACS (61.5%) than in SA (18.2%) and asymptomatic (14.3%) (p<0.05). Thrombus was detected in all NR cases. Fibrous cap thickness was lower in NR lesions compared to lesions without NR (48±21 μm versus 104±58μm, p<0.01). Lipid content tended to be higher in lesions with NR (260±103° versus 203±85°, p=0.051). Lesions with NR had more often dense macrophage infiltration (84.2% versus 44.0%, p<0.05). There were no differences in neovascularization or calcifications between lesions with or without NR. Conclusions: Neoatherosclerosis is frequent and more common among symptomatic patients. Importantly, neointimal rupture is associated with ACS late after stent implantation. Specific morphological characteristics, such as cap thickness and macrophage infiltration are associated with rupture of neoatherosclerotic plaques.

Purpose: In-stent neoatherosclerosis has been recognised in pathologic specimens of bare metal stents (BMS), and recently in first generation drug eluting stents (1st-DES), as well. However, in vivo data are scarce. By optical coherence tomography, we investigated the incidence and morphological characteristics of neoatherosclerosis (NA) very late after BMS or 1st-DES implantation. Methods: From 1/1/2007 to 31/1/2012, 52 patients from two institutions underwent >24 months follow-up OCT assessment of a BMS or a 1st-DES (13 BMS – 39 1st-DES). NA was characterized using criteria for native atherosclerosis. Results: BMS had longer follow-up interval but no differences in clinical presentation at follow-up. No significant differences were evident in the incidence of NA, neointimal rupture, lipid content, neovascularization or macrophage infiltration between BMS and 1st-DES. There was however a trend for lower fibrous cap thickness (FCT) and for higher calcification in BMS (FCT: 51±31 μm vs. 92±59 μm, p=0.057; calcifications: 46.2% vs. 15.4%, p=0.051). 1st-DES with neoatherosclerosis had longer interval from implantation compared to 1st-DES with homogeneous coverage [Median 71 months (range 25-130) vs. 57 months (24-68), p<0.05], but there was no difference for BMS with or without neoatherosclerosis [Median 125 months (range 90-201) vs. 168 months (132-168), p=0.63]. Conclusions: The incidence and morphological characteristics of NA are similar between 1st-DES and BMS of more prolonged follow-up. Our findings suggest a time-dependent pattern in the incidence of NA in 1st-DES with 2-11 years follow-up.

We investigated electrophysiological and histological effect on canine anatomical isthmus in right atrium by photosensitization reaction (PR) of talaporfin sodium operated via a manipulative 7 Fr. laser catheter to establish a nonthermal tachyarrhythmia treatment. We continuously administrated talaporfin sodium via a left femoral vein to maintain photosensitizer concentration of 25-35 μg/ml in blood plasma, which is within the range of clinical use in human. Fifteen-minute after kickoff of the photosensitizer administration, a 663 nm laser was irradiated via the laser catheter for 30 s/point with irradiance of 10 W/cm2. After 17 times irradiations, a 23 ms delay of the electrical signal propagation along tricuspid annulus was observed. This result might demonstrate the acute electrical conduction delay induced by PR. The canine heart was extracted 10 days after PR and Azan staining specimen was histologically evaluated to investigate the myocardial damage by PR. The transmural fibrosis in anatomical isthmus was found. We demonstrated the PR-induced electrical conduction delay in acute phase in vivo using continuous photosensitizer dosed canine model, which maintain the clinical photosensitizer concentrat

Suture ligation of blood vessels during surgery can be time-consuming and skill-intensive. Energy-based, electrosurgical and ultrasonic devices have recently replaced sutures for many surgical procedures, providing rapid hemostasis during surgery. However, these devices have the potential to create large collateral zones of thermal damage and tissue necrosis. This study explores infrared (IR) lasers as an alternative technology for rapid and precise thermal coagulation and sealing of blood vessels. Eight near-IR lasers (808, 980, 1075, 1470, 1550, 1850- 1880, 1908, and 2120 nm) were tested. Preliminary studies were performed using fresh porcine renal vessels, ex vivo, with diameters of 1-6 mm, compressed to a thickness of 0.4 mm. A linear beam profile was then applied normal to the vessel for narrow, full-width thermal coagulation. Laser irradiation time was 5 s. Vessel burst pressure measurements were used to determine seal strength. The 1470 nm laser wavelength sealed a wide range of vessel diameters from 1-6 mm. Other lasers (1550, 1850-1880, and 1908 nm) also sealed vessels, but were limited by suboptimal seal pressures, excessive charring, and/or limited power output preventing treatment of large vessels.

We evaluated the utility of a compact and high-power quantum cascade laser (QCL) in the 5.7 μm wavelength range for less-invasive laser angioplasty. Atherosclerotic plaques mainly consist of cholesteryl esters. The wavelength of 5.75 μm is well absorbed in C=O stretching vibration mode of cholesteryl esters. Our previous study achieved to make cutting differences between a normal tunica intima of an artery and an atherosclerotic lesions using a nanosecond pulsed laser by difference-frequency generation (DFG laser) at the wavelength of 5.75 μm. For realizing a clinical application of this technique, a compact laser device is required. In this study, QCL irradiation effects to a porcine normal aorta were compared with DFG laser. In addition QCL irradiation effects to an atherosclerotic aorta of myocardial infarction-prone Watanabe heritable hyperlipidemic rabbit (WHHLMI rabbit) and a normal aorta were observed. As a result, the QCL could make cutting difference between the rabbit atherosclerotic aorta and the normal aorta. On the other hand, the QCL induced more thermal damage to porcine normal aorta than the DFG laser at the irradiation condition of comparable ablation depth. In conclusion, the possibility of less-invasive and selective treatment of atherosclerotic plaques using the QCL in the 5.7 μm wavelength range was revealed, although improvement of QCL was required to prevent the thermal damage of a normal artery.

The purpose of this study was to investigate the artery dilatation performance of the short-duration heating balloon catheter in cadaver stenotic arteries. We designed a prototype short-duration heating balloon catheter that can heat artery media to around 60 °C in 15−25 s by a combination of laser-driven heat generation and continuous fluid irrigation in the balloon. We performed ex vivo short-duration heating dilatation in the cadaver atherosclerotic femoral arteries (initial percent diameter stenosis was 36-98%), with the maximum balloon temperature of 65±5 °C, laser irradiation duration of 25 s, and balloon dilatation pressure of 3.5 atm. The artery lumen configurations before and after the dilatations were assessed with a commercial IVUS system. After the short-duration heating dilatations, the percent diameter stenosis was reduced below 30% without any artery tears or dissections. We estimated that the artery media temperature was raised to around 60 °C in which plaque thickness was below 0.8 mm by a thermal conduction calculation. The estimated maximum temperature in artery adventitia and surrounding tissue was up to 45 °C. We found that the short-duration heating balloon could sufficiently dilate the cadaver stenotic arteries, without thermal injury in artery adventitia and surroundings.

We demonstrate visualization of lipid distribution in in-vitro artery model by 1.7-μm spectroscopic spectral-domain optical coherence tomography (SD-OCT). In the demonstration, we measure spectral fringes by a spectrometer with an extended InGaAs line sensor and a super-continuum (SC) light source whose spectrum is arranged to have its maximum intensity in 1.7-μm band. The OCT system has an axial resolution of 21μm, a measurement range of 5mm and a sensitivity of 108dB with an A-scan rate of 0.96kHz, which is limited by the noise of the available SC light source. The in-vitro model is made by injecting lipid into swine carotid artery, which is compared to intact artery. We perform Bscan of the model in water by connecting an OCT probe to the OCT system and pulling the probe back at 0.027mm/sec with a rotation rate of 112rpm. For visualizing lipid distribution, we adopt a spectroscopic OCT algorism where the detected spectral fringe is divided into six sub-bands, the set of the sub-band A-scans are fitted to a model accounting absorption characteristics of lipid with its peak at 1726nm, and the content of lipid is estimated as lipid score. As a result, the p-value of the lipid score between normal artery and plaque one is less than 1E-10 in 1-mm depth from the surface, which is significant of visualization of lipid distribution.

Hyperspectral imaging (HSI) of rabbit atherosclerotic plaque in near-infrared (NIR) range from 1150 to 2400 nm was demonstrated. A method to identify vulnerable plaques that are likely to cause acute coronary events has been required. The object of this study is identifying vulnerable plaques by NIR-HSI for an angioscopic application. In this study, we observed the hyperspectral images of the atherosclerotic plaque in WHHLMI rabbit (atherosclerotic rabbit) artery under simulated angioscopic conditions by NIR-HSI. NIR-HSI system was constructed by a NIR super continuum light and a mercury-cadmium-telluride camera. Spectral absorbance values (log (1/R) data) were obtained in the wavelength range from 1150 to 2400 nm at 10 nm intervals. The hyperspectral images were constructed with spectral angle mapper algorithm. As a result, the detections of atherosclerotic plaque under angioscopic observation conditions were achieved especially in the wavelength around 1200 nm, which corresponds to the second overtone of CH stretching vibration mode. The NIR-HSI was considered to serve as an angioscopic diagnosis technique to identify vulnerable plaques without clamping and saline injection.

In this study we test the feasibility of using low-cost LEDs to selectivity heat blood for enhanced thermal imaging of vascular structures. Applications of this new imaging technique include mapping blood vessels during surgeries such as tumor removal and vascular repair. In addition, this technique could potentially be used to determine the location of increased vascular density, and thus breast cancer tumors. Porcine blood, skeletal muscle, skin and fat were illuminated with LEDs that emit at 405 nm and 530 nm (near the blood absorption peaks) and the increase in temperature as a function of time was recorded using a thermal camera. In the studies with the 530 nm LED, blood heated more than other tissue types and the heating rate for the blood was significantly faster than other tissues. Illumination of blood with the 530 nm LED at low powers (tissue irradiance <500 mW/cm²) will selectively heat blood with no damage to surrounding tissue. Illumination with the 405 nm LED produced large temperature changes (up to 15°C) at low LED powers (tissue irradiance <500 mW/cm²). The heating and heating rates measured with this LED were higher than those measured for the 530nm LED. However, blood, skin and fat showed comparable amounts of heating and heating rates. The amount of heating in muscle tissue was dependent on the skeletal muscle type, but most samples showed heating comparable to or larger than blood. This LED was not effective at selectively heating blood relative to the other tissue types. The results of the preliminary studies suggest that the best contrast can be achieved with pulsed 530 nm LED illumination and an image analysis method that highlights rapid changes in temperature.

We performed the independent component analysis of the hyperspectral functional near-infrared data acquired on humans during exercise and rest. We found that the hyperspectral functional data acquired on the human brain requires only two physiologically meaningful components to cover more than 50% o the temporal variance in hundreds of wavelengths. The analysis of the spectra of independent components showed that these components could be interpreted as results of changes in the cerebral blood volume and blood flow. Also, we found significant contributions of water and cytochrome c oxydase into changes associated with the independent components. Another remarkable effect of ICA was its good performance in terms of the filtering of the data noise.

A time-resolved, spectroscopic, diffuse optical tomography device was assembled for clinical applications like brain functional imaging. The entire instrument lies in a unique setup that includes a light source, an ultrafast time-gated intensified camera and all the electronic control units. The light source is composed of four near infrared laser diodes driven by a nanosecond electrical pulse generator working in a sequential mode at a repetition rate of 100 MHz. The light pulses are less than 80 ps FWHM. They are injected in a four-furcated optical fiber ended with a frontal light distributor to obtain a uniform illumination spot directed towards the head of the patient. Photons back-scattered by the subject are detected by the intensified CCD camera. There are resolved according to their time of flight inside the head. The photocathode is powered by an ultrafast generator producing 50 V pulses, at 100 MHz and a width corresponding to a 200 ps FWHM gate. The intensifier has been specially designed for this application. The whole instrument is controlled by an FPGA based module. All the acquisition parameters are configurable via software through an USB plug and the image data are transferred to a PC via an Ethernet link. The compactness of the device makes it a perfect device for bedside clinical applications. The instrument will be described and characterized. Preliminary data recorded on test samples will be presented.

In this study, we demonstrate the use of orthogonal diffuse reflectance spectroscopy (o-DRS) to assess brain dysfunction and to monitor internal temperature variations during heatstroke in intact mice brains (n=6). Heatstroke is a medical emergency defined by abnormally elevated body temperature greater than 40°C that causes biochemical, physiological and hematological changes (multiorgan damage). Therefore, quick diagnosis and management of heatstroke victims is essential for good outcomes. Current clinical methods for monitoring temperature (invasive and noninvasive) suffers from several drawbacks such as complexity, cost, portability, safety, etc. To overcomes these deficiencies, a DRS working at the spectral range of 600-1000nm in orthogonal mode together with numerical processing have been applied to First, monitor cerebral optical changes, Second, evaluate rise in temperature and Third, to predict internal temperature noninvasively. Heatstroke was induced by exposing of the anesthetized mouse body, placed above controlled heating pad, to a high ambient temperature with increasing intervals of 1°C until death. Experimental results show variations in both absorption and scattering during heatstroke which emphasizes the changes in brain chromophores and morphology that occur during temperature elevation. In addition, a reflectance-temperature index was developed and found to correlate well with the measured temperature. Our preliminary results suggest that our o-DRS have the potential to monitor and assess internal temperature variations and thus may serve as a useful tool in clinical and laboratory settings.

Carotid endarterectomy is a common vascular surgical procedure which may help prevent patients’ risk of having a stroke. A high resolution real-time imaging technique that can detect the position and size of vascular plaques would provide great value to reduce the risk level and increase the surgical outcome. Optical coherence tomography (OCT), as a high resolution high speed noninvasive imaging technique, was evaluated in this study. Twenty-four 24-week old apolipoprotein E-deficient (ApoE-/-) mice were divided into three groups with 8 in each. One served as the control group fed with normal diet. One served as the study group fed with high-fat diet to induce atherosclerosis. The last served as the treatment group fed with both high-fat diet and medicine to treat atherosclerosis. Full-range, complex-conjugate-free spectral-domain OCT was used to image the mouse aorta near the neck area in-vivo with aorta exposed to the imaging head through surgical procedure. 2D and 3D images of the area of interest were presented real-time through graphics processing unit accelerated algorithm. In-situ imaging of all the mice after perfusion were performed again to validate the invivo detection result and to show potential capability of OCT if combined with surgical saline flush. Later all the imaged arteries were stained with H and E to perform histology analysis. Preliminary results confirmed the accuracy and fast imaging speed of OCT imaging technique in determining atherosclerosis.

In this work, we explored the potential of measuring shear wave propagation using Optical Coherence Elastography (OCE) in a layered phantom and based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a piezoelectric transducer transmitting sine-wave bursts of 400 μs, synchronized with an OCT swept source wavelength sweep imaging system. The acoustic radiation force was applied to layered phantoms. The phantoms were composed of gelatin and titanium dioxide. Differential OCT phase maps, measured with and without the acoustic radiation force, demonstrate microscopic displacement generated by shear wave propagation in these phantoms of different stiffness. The OCT phase maps are acquired with a swept-source OCT (SS-OCT) system. We present a technique for calculating tissue mechanical properties by propagating shear waves in inhomogeneous tissue equivalent phantoms using the Acoustic Radiation Force (ARF) of an ultrasound transducer, and measuring the shear wave speed and its associated properties in the different layers with OCT phase maps. This method lays the foundation for future studies of mechanical property measurements of heterogeneous tissue structures, with applications in the study of aneurysms and other intravascular pathologies.

Blood flow velocity and volumetric flow measurements are important parameters for assessment of the severity of stenosis and the outcome of interventional therapy. However, feasibility of intravascular flow measurement using a rotational catheter based phase resolved Doppler optical coherence tomography (DOCT) is difficult. Motion artefacts induced by the rotating optical imaging catheter, and the radially dependent noise background of measured Doppler signals are the main challenges encountered. In this study, a custom-made data acquisition system and developed algorithms to remove non-uniform rotational distortion (NURD) induced phase shift artefact by tracking the phase shift observed on catheter sheath. The flow velocity is calculated from Doppler shift obtained by Kasai autocorrelation after motion artefact removal. Blood flow velocity profiles in porcine carotid arteries in vivo were obtained at 100 frames/s with 500 A-lines/frame and DOCT images were taken at 20 frames/s with 2500 A-lines/frame. Time-varying velocity profiles were obtained at an artery branch. Furthermore, the identification of a vein adjacent to the catheterized vessel based on the color Doppler signal was also observed. The absolute measurement of intravascular flow using a rotating fiber catheter can provide insights to different stages of interventional treatment of stenosis in carotid artery.

The pathology of multiple sclerosis (MS) involves both the gray and white matter regions of the brain and spinal cord. It is characterized by various combinations of demyelination, inflammatory infiltration, axonal degeneration, and later gliosis in chronic lesions. While acute and chronic white matter plaques are well characterized and easily identified, evidence indicates that the CNS of MS patients may be globally altered, with subtle abnormalities found in grossly normal appearing white matter (NAWM) and in diffusely abnormal white matter (DAWM) where histochemical stains and advanced magnetic resonance imaging indicate altered tissue composition. Thus, the prototypical acute inflammatory lesion may merely represent the most obvious manifestation of a chronic widespread involvement of the CNS, which is difficult to examine reliably. The current study deals with the microstructure and biochemistry of demyelination, remyelination and axonal loss in various regions of post-mortem human MS brain, including NAWM, areas of remyelination and more typical acute and chronic lesions. The myelin sheath, neuroglia and perivascular spaces were investigated using a novel Coherent Anti-Stokes Raman Scattering (CARS) microscope with simultaneous Two-Photon Excited Fluorescence (TPEF) imaging. The active CH stretching region between ~ 2800 and 3000 cm^-1 was probed to provide chemically specific, high resolution, label-free imaging pertaining to the progression of the disease. CARS data were correlated with TPEF and conventional histochemical and immunohistochemical stains. Our novel CARS microscopy system provides detailed morphological and biochemical information regarding CNS pathology in MS and that may be applicable to a broad range of other human brain and spinal cord disorders.

Time-resolved thermography is a novel method to assess thermal variations and heterogeneities in tissue and blood. The recent generation of thermal cameras provides a sensitivity of less than mK. This high sensitivity in conjunction with non-invasive, label-free and radiation-free monitoring makes thermography a promising tool for intrasurgical diagnostics. In brain surgery, time-resolved thermography can be employed to distinguish between normal and anomalous tissue. In this study, we investigated and discussed the potential of time-resolved thermography in neurosurgery for the intraoperative detection and demarcation of tumor borders. Algorithms for segmentation, reduction of movement artifacts and image fusion were developed. The preprocessed image stacks were subjected to discrete wavelet transform to examine individual frequency components. K-means clustering was used for image evaluation to reveal similarities within the image sequence. The image evaluation shows significant differences for both types of tissue. Tumor and normal tissues have different time characteristics in heat production and transfer. Furthermore, tumor could be highlighted. These results demonstrate that time-resolved thermography is able to support the detection of tumors in a contactless manner without any side effects for the tissue. The intraoperative usage of time-resolved thermography improves the accuracy of tumor resections to prevent irreversible brain damage during surgery.

Functional near-infrared spectroscopy (fNIRS) is a non-invasive imaging technique which measures the hemodynamic changes that reflect the brain activity. Diffuse optical tomography (DOT), a variant of fNIRS with multi-channel NIRS measurements, has demonstrated capability of three dimensional (3D) reconstructions of hemodynamic changes due to the brain activity. Conventional method of DOT image analysis to define the brain activation is based upon the paired t-test between two different states, such as resting-state versus task-state. However, it has limitation because the selection of activation and post-activation period is relatively subjective. General linear model (GLM) based analysis can overcome this limitation. In this study, we combine the 3D DOT image reconstruction with GLM-based analysis (i.e., voxel-wise GLM analysis) to investigate the brain activity that is associated with the risk-decision making process. Risk decision-making is an important cognitive process and thus is an essential topic in the field of neuroscience. The balloon analogue risk task (BART) is a valid experimental model and has been commonly used in behavioral measures to assess human risk taking action and tendency while facing risks. We have utilized the BART paradigm with a blocked design to investigate brain activations in the prefrontal and frontal cortical areas during decision-making. Voxel-wise GLM analysis was performed on 18human participants (10 males and 8females).In this work, we wish to demonstrate the feasibility of using voxel-wise GLM analysis to image and study cognitive functions in response to risk decision making by DOT. Results have shown significant changes in the dorsal lateral prefrontal cortex (DLPFC) during the active choice mode and a different hemodynamic pattern between genders, which are in good agreements with published literatures in functional magnetic resonance imaging (fMRI) and fNIRS studies.

Investigation of the reliability and reproducibility of the hemodynamic response is important for interpretation and understanding of the results of functional near-infrared spectroscopy (fNIRS). It measures optical signals absorbed by the brain tissue and reflects the neuronal activities indirectly. Here we described an fNIRS study measured in the prefrontal region (Brodman area 9, 10, part of 46)to examine the risk decision-making behavior in nine young adults. The Balloon Analog Risk Task (BART) is widely used to test the level of risk taking ability in the field of psychology. BART was a protocol utilized in this study to evoke a risk-taking environment with a gambling-like balloon game in each subject. Specifically, we recorded the brain oxygenated-hemoglobin (HbO) and deoxygenated-hemoglobin (HHb) changes during the two repeated measurements within a time interval of 3 weeks. The results demonstrate that the changes in HbO2 amplitudes have high reliability at the group level, and that the spatial patterns of the tomographic images have high reproducibility in size and a moderate degree of overlap. Overall, this study confirms that the hemodynamic response to risk decision-making (i.e., BART) seen by fNIRS is highly reliable and reproducible.

Cerebral palsy (CP) is a term that describes a group of motor impairment syndromes secondary to genetic and/or acquired disorders of the developing brain. In the current study, NIRS and motion capture were used simultaneously to correlate the brain’s planning and execution activity during and with arm movement in healthy individual. The prefrontal region of the brain is non-invasively imaged using a custom built continuous-wave based near infrared spectroscopy (NIRS) system. The kinematics of the arm movement during the studies is recorded using an infrared based motion capture system, Qualisys. During the study, the subjects (over 18 years) performed 30 sec of arm movement followed by 30 sec rest for 5 times, both with their dominant and non-dominant arm. The optical signal acquired from NIRS system was processed to elucidate the activation and lateralization in the prefrontal region of participants. The preliminary results show difference, in terms of change in optical response, between task and rest in healthy adults. Currently simultaneous NIRS imaging and kinematics data are acquired in healthy individual and individual with CP in order to correlate brain activity to arm movement in real-time. The study has significant implication in elucidating the evolution in the functional activity of the brain as the physical movement of the arm evolves using NIRS. Hence the study has potential in augmenting the designing of training and hence rehabilitation regime for individuals with CP via kinematic monitoring and imaging brain activity.

Combination therapies of photochemical internalization (PCI) and hyperthermia (HT) were investigated in an in vitro system consisting of human glioma spheroids. Spheroids (350-400 μm dia.) were irradiated with 670 nm laser light in an incubator at temperatures ranging from 37 to 50 °C. For each temperature investigated (45 min. heating time), spheroids were divided into 5 groups: control, dark control, bleomycin-only, photodynamic therapy (PDT), and PCI. PDT and PCI spheroids were exposed to radiant exposures ranging from 0.5-3.0 J cm^-2 using an irradiance of 5 mW cm^-2. Toxicity was evaluated from spheroid growth kinetics. The combination of PCI and HT resulted in growth delays over a very narrow range of radiant exposures (1.5 – 2.5 J cm^-2) and temperatures (40 – 42 °C).

Hindbrains of sedated, prone, suckling rats were irradiated 11-13 days postpartum horizontally from the left with an array of upright wiggler-generated synchrotron X-ray microbeams spaced either 105 or 210 μm apart. The microbeams were in an array of 48 (for the 205 μm interval) or of 96 (for the 105 μm interval), with microbeam widths ranging from 19 to 39 μm, the array having an approximately 1-cm-square cross section. The microbeams imparted doses of either ≈50 or ≈150 Gy to the inner skin (computed here as the average dose 0.5–1.5 mm deep to the surface of our phantom) at their entrance to the head, where their median energy was ≈120 keV. The array traversed the postero-superior quadrant of the phantom, which represented the occiput of the head, so that about one in five photons in the array bypassed the head altogether. The resultant radiation doses to the head were simulated by computing the tracks of thirty billion X-ray photons incident on the multislit collimator along with all ≥1 keV secondary electrons from interactions in water of the photons entering the left circular wall of the 1.00 cm-radius, 1.55 cm-wide (i.e., "15.5 mm-long") cylindrical head phantom. The computations were performed using the Los Alamos National Laboratory Monte Carlo radiation transport computer program MCNPX, yielding ionization energies imparted to approximately twenty-four thousand 1.00 mmdeep, 10 μm-wide, up to 3.33 mm-high voxels distributed throughout one quadrant of the phantom, each representing up to 33.3 μg water. Computed nadir doses between microbeams were defined as the average of the three lowest doses between horizontally adjacent peak doses. We notice that nadir interbeam doses under 5 Gy were associated with neurologically minor and/or inconsequential sequelae fifteen months after irradiation and thus postulate that unidirectional microbeam radiosurgery using hindbrain nadir doses under 5 Gy may safely ameliorate the symptoms of some presently intractable human infantile neuraxial malignancies.

Plants have mechanisms to perceive and transmit information between its organs and tissues. These signals had long been considered as hormonal or hydraulic in nature, but recent studies have shown that electrical signals are also produced causing physiological responses. In this work we show that Venus Flytrap, Dionaea muscipula, can respond to both electrical and optical signals beside mechanical stimulations. While the Venus Flytrap does not have any neurons, it does contain transport cells with very similar characteristics to neurotransmitters and uses ionic mechanisms, as human neurons do, to generate action potentials. In our electrical stimulation study, electrodes made out of soft cloth were soaked in salt water before being placed to the midrib (+) and lobe (-). The flytrap's surface resistance was determined by subtracting out the average electrode resistance from the measured electrode to plant surface resistance, yielding an average contact resistance of around 0.98MΩ. A logarithmic amplifier was used to monitor mechanically generated electrical signals. Two electrical pulses were generated by mechanically touching the trigger hairs in the lobe twice within 20 seconds. By discharging around 600μC charge stored in a capacitor we demonstrated electrically closing of the flytrap. For optical excitation we found in our FTIR study it's tissue contains very similar protein absorption peaks to that of insects. A 7.35μm laser with ~50mw power was then used for the stimulation study. Electrical action potential was generated twice by mid-infrared photons before closure of the flytrap.

Neurovascular dysfunction in many neurodegenerative diseases, such as Alzheimer’s disease (AD), reduces blood flow to affected brain areas and causes neuronal dysfunction and loss. A new optical imaging technique is developed to activate astrocytes in live animal models in order to investigate the increase of local cerebral blood flow as a potential therapeutic strategy for AD. The technique uses fluorescent labeling of vasculature and astrocytes coupled with intravital 2-photon microscopy to visualize the astrocyte-vasculature interactions in live animals. Using femtosecond laser stimulation, calcium uncaging is applied to specifically target and activate astrocytes in vivo with high spatial and temporal resolutions. Intravital 2-photon microscopy imaging was employed to demonstrate that single endfoot optical activation around an arteriole induced a 25% increase in arteriole diameter, which in turn increased cerebral local blood flow in down-stream capillaries. This quantitative result indicates the potential of using optical activation of astrocytes in afflicted brain areas of neurodegeneration to restore normal neurovascular functions.

Deep brain stimulation (DBS) of the cholinergic nuclei has emerged as a powerful potential treatment for neurodegenerative disease and is currently in a clinical trial for Alzheimer’s therapy. While effective in treatment for a number of conditions from depression to epilepsy, DBS remains somewhat unpredictable due to the heterogeneity of the projection neurons that are activated, including glutamatergic, GABAergic, and cholinergic neurons, leading to unacceptable side effects ranging from apathy to depression or even suicidal behavior. It would be highly advantageous to confine stimulation to specific populations of neurons, particularly in brain diseases involving complex network interactions such as Alzheimer’s. Optogenetics, now firmly established as an effective approach to render genetically-defined populations of cells sensitive to light activation including mice expressing Channelrhodopsin-2 specifically in cholinergic neurons, provides just this opportunity. Here we characterize the light activation properties and cell density of cholinergic neurons in healthy mice and mouse models of Alzheimer’s disease in order to evaluate the feasibility of using optogenetic modulation of cholinergic synaptic activity to slow or reverse neurodegeneration. This paper is one of the very first reports to suggest that, despite the anatomical depth of their cell bodies, cholinergic projection neurons provide a better target for systems level optogenetic modulation than cholinergic interneurons found in various brain regions including striatum and the cerebral cortex. Additionally, basal forebrain channelrhodopsin-expressing cholinergic neurons are shown to exhibit normal distribution at 60 days and normal light activation at 40 days, the latest timepoints observed. The data collected form the basis of ongoing computational modeling of light stimulation of entire populations of cholinergic neurons.

Optical nerve stimulation (ONS) is being explored for identification and preservation of the cavernous nerves (CN), responsible for erectile function, during prostate cancer surgery. This study compares three pulsed infrared lasers to determine whether differences in spectral linewidth and/or temporal pulse profile influence successful ONS of CN. Infrared laser radiation from the Capella diode laser (1873 nm, 5 ms, 10 Hz), Thulium fiber laser (TFL) (1873 nm, 5 ms, 10 Hz), and solid-state Holmium:YAG laser (2120 nm, 200 μs, 5 Hz) were transmitted through 400-μm-corediameter optical fibers, producing a 1-mm-diameter-spot on the nerve surface. Successful ONS was judged by an intracavernous pressure (ICP) response in the penis (n =10 rats) during a total stimulation time of 30 s. The narrow linewidth TFL (Δλ ~ 0.5 nm) and broad linewidth Capella laser (Δλ ~ 12 nm) performed similarly, producing ICP responses with a threshold radiant exposure of ~ 0.45 J/cm², and ICP response times of 12-17 s, while the Holmium laser stimulated at ~ 0.59 J/cm², and ICP response times of about 14-28 s. All three lasers demonstrated successful ONS of CN. ICP response time was dependent on the rate of energy deposition into the CN, rather than linewidth or temporal pulse profile.

Infrared neural stimulation (INS) describes a method, by which an infrared laser is used to stimulate neurons. The major benefit of INS over stimulating neurons with electrical current is its spatial selectivity. To translate the technique into a clinical application it is important to know the energy required to stimulate the neural structure. With this study we provide measurements of the radiant exposure, at the target structure that is required to stimulate the auditory neurons. Flat polished fibers were inserted into scala tympani so that the spiral ganglion was in front of the optical fiber. Angle polished fibers were inserted along scala tympani, and rotating the beveled surface of the fiber allowed the radiation beam to be directed perpendicular to the spiral ganglion. The radiant exposure for stimulation at the modiolus for flat and angle polished fibers averaged 6.78±2.15 mJ/cm². With the angle polished fibers, a 90º change in the orientation of the optical beam from an orientation that resulted in an INS-evoked maximum response, resulted in a 50% drop in the response amplitude. When the orientation of the beam was changed by 180º, such that it was directed opposite to the orientation with the maxima, minimum response amplitude was observed.

Among neural prostheses cochlear implants (CIs) are considered the most successful devices. They restore some hearing to ~210,000 severe-to-profound hearing impaired people. Despite the devices’ success, the performance of the implanted individuals in noisy environments is poor and music perception is rudimentary. It has been argued that increasing the number of independent channels for stimulation can improve the performance of a CI user in challenging hearing environments. An optical method, stimulating neurons with infrared radiation, has been suggested as a novel approach to increase the number of independent channels. Infrared neural stimulation (INS) works through the deposition of heat into the tissue. Thermal damage is therefore a potential risk, particularly for longterm exposure. To verify the efficacy and safety of INS, cats were implanted for about 4 weeks and were continuously stimulated daily for 6-8 hours. Cochlear function did not change during the stimulation, and histology did not reveal signs of damage. Tissue growth following the implantation was largely localized at the cochleostomy.

Responses of units in the central nucleus of the inferior colliculus of the guinea pig were recorded with tungsten electrodes. The set of data presented here is limited to high stimulus levels. The effect of changing the modulation frequency and the modulation depth was explored for acoustic and laser stimuli. The selected units responded to sinusoidal amplitude modulated (AM) tones, AM trains of clicks, and AM trains of laser pulses with a modulation of their spike discharge. At modulation frequencies of 20 Hz, some units tended to respond with 40 Hz to the acoustic stimuli, but only at 20 Hz for the trains of laser pulses. For all modes of stimulation the responses revealed a dominant response to the first cycle of the modulation, with decreasing number of action potential during successive cycles. While amplitude modulated tone bursts and amplitude modulated trains of acoustic clicks showed similar patterns, the response to trains of laser pulses was different.

Spatial selective infrared neural stimulation has potential to improve neural prostheses, including cochlear implants. The heating of a confined target volume depolarizes the cell membrane and results in an action potential. Tissue heating may also results in thermal damage or the generation of a stress relaxation wave. Stress relaxation waves may result in a direct mechanical stimulation of remaining hair cells in the cochlea, so called optophony. Data are presented that quantify the effect of an acoustical stimulus (noise masker) on the response obtained with INS in normal hearing, acutely deafened, and chronic deaf animals. While in normal hearing animals an acoustic masker can reduce the response to INS, in acutely deafened animals the masking effect is reduced, and in chronic deaf animals this effect has not been detected. The responses to INS remain stable following the different degrees of cochlear damage.

Penetrating waveguide arrays made of glass (SiO_O) and silicon were fabricated for infared (IR) neural stimulation to provide 3D access to the brain or peripheral nerves for selective deep-tissue stimulation with different spatiotemporal patterns. Comprehensive bench characterization was performed to determine light delivery and loss mechanisms. Fused silica/quartz arrays have optrodes of constant geometry with a pyramidal tip at the end of a straight-edge shank; length, width, and tip angle of each optrode can be varied independently from array to array. Undoped silicon arrays are similar in form to the Utah Slant Electrode Array, which has tapered microneedles of varying length in one direction. Light transmission efficiency was investigated with input from different optical fibers. With a 120-μmm wide and 1.5-mm long glass optrode having a tip taper angle of 45° with respect to the optical axis, 70% of IR light from a butt-coupled 50-μm fiber is transmitted out of the tips; shank length and tip taper does not affect the output power. However, transmission is only 39% for a 1.5- mm long Si optrode, and less for shorter more tapered optrodes. Similar beam profiles were obtained for both arrays when glass optrodes have a 45° tip taper; decreasing the glass optrode tip angle to 30° increases the full-angle divergence from 15° to 55°, which leads to a wider yet shallower illumination volume. Results reveal that the dominant source of loss in both devices is from total internal reflection within the tips. Additional losses in silicon include tapered shank radiation and reflection from its high refractive index.

We present two innovative design concepts of integrated flexible neural probe for deep brain optical stimulation and electrical recording, termed as “optitrode”. In the first one, a hybrid annular light pipe is built around a tetrode by V-groove guided capillary assembly (VGCA), by which a single or multiple microwires can be packaged inside the light pipe with high precision. In the second design, thin-film microelectrodes and wires are patterned on an optical fiber by proximity ion beam lithography. These designs address a major limitation on the length-to-diameter ratio, achieving > 500 (>5 cm long, <100 μm diameter). The highly flexible nature of optitrode could be critical for minimally-invasive implantation as well as long-term operation.

Electrical stimulation of the human cortex in conjunction with physical rehabilitation has been a valuable approach in facilitating the plasticity of the injured brain. One such method is transcranial direct current stimulation (tDCS) which is a non-invasive method to elicit neural stimulation by delivering current through electrodes placed on the scalp. In order to better understand the effects tDCS has on cortical plasticity, neuroimaging techniques have been used pre and post tDCS stimulation. Recently, neuroimaging methods have discovered changes in resting state cortical hemodynamics after the application of tDCS on human subjects. However, analysis of the cortical hemodynamic activity for a physical task during and post tDCS stimulation has not been studied to our knowledge. A viable and sensitive neuroimaging method to map changes in cortical hemodynamics during activation is functional near-infrared spectroscopy (fNIRS). In this study, the cortical activity during an event-related, left wrist curl task was mapped with fNIRS before, during, and after tDCS stimulation on eight healthy adults. Along with the fNIRS optodes, two electrodes were placed over the sensorimotor hand areas of both brain hemispheres to apply tDCS. Changes were found in both resting state cortical connectivity and cortical activation patterns that occurred during and after tDCS. Additionally, changes to surface electromyography (sEMG) measurements of the wrist flexor and extensor of both arms during the wrist curl movement, acquired concurrently with fNIRS, were analyzed and related to the transient cortical plastic changes induced by tDCS.

Functional neurological imaging has been shown to be valuable in evaluating brain plasticity in children with cerebral palsy (CP). In recent studies it has been demonstrated that functional near-infrared spectroscopy (fNIRS) is a viable and sensitive method for imaging motor cortex activities in children with CP. However, during unilateral finger tapping tasks children with CP often exhibit mirror motions (unintended motions in the non-tapping hand), and current fNIRS image formation techniques do not account for this. Therefore, the resulting fNIRS images contain activation from intended and unintended motions. In this study, cortical activity was mapped with fNIRS on four children with CP and five controls during a finger tapping task. Finger motion and arm muscle activation were concurrently measured using motion tracking cameras and electromyography (EMG). Subject-specific regressors were created from motion capture and EMG data and used in a general linear model (GLM) analysis in an attempt to create fNIRS images representative of different motions. The analysis provided an fNIRS image representing activation due to motion and muscle activity for each hand. This method could prove to be valuable in monitoring brain plasticity in children with CP by providing more consistent images between measurements. Additionally, muscle effort versus cortical effort was compared between control and CP subjects. More cortical effort was required to produce similar muscle effort in children with CP. It is possible this metric could be a valuable diagnostic tool in determining response to treatment.

Current technologies for monitoring neural activity either use different variety of electrodes (electrical recording) or require contrast agents introduced exogenously or through genetic modification (optical imaging). Here we demonstrate an optical method for non-contact and contrast agent free detection of nerve activity using phase-resolved optical coherence tomography (pr-OCT). A common-path variation of the pr-OCT is recently implemented and the developed system demonstrated the capability to detect rapid transient structural changes that accompany neural spike propagation. No averaging over multiple trials was required, indicating its capability of single-shot detection of individual impulses from functionally stimulated Limulus optic nerve. The strength of this OCT-based optical electrode is that it is a contactless method and does not require any exogenous contrast agent. With further improvements in accuracy and sensitivity, this optical electrode will play a complementary role to the existing recording technologies in future.

Paget’s disease of bone affects about 1 to 3 percent of people over 40 years of age in the United States. The disease is characterized by an increase in the rate of bone remodeling due to excessive osteoclast activity; therefore patients with Paget’s disease can develop severe bone deformities. Pagetoid bones are large, fragile and prone to fractures. A hallmark of Paget’s disease of bone is a marked increase in vascularization in bones. The fingerprint determinants of vascularization are deoxyhemoglobin (Hb) and oxyhemoglobin (HbO₂), which are the key chromophores in the NIR “tissue optical window” from 700nm to 1200nm. We have designed a Bone Optical Analyzer which utilizes optical spectroscopy imaging to non-invasively measure the changes of Hb and HbO₂, thus enabling early diagnosis and monitoring of disease progression in these patients. Using inverse imaging algorithms, based on the diffusion equation, 2D and 3D maps of the bone’s internal structure can be reconstructed. The use of NIR light will allow for repeated studies on patients with Paget’s disease quickly, safely, inexpensively and without the risks associated with standard procedures. The model will be tested on bone tissue phantoms which mimic the scattering properties of human bone. This work will be the foundation for the future use of this device in vivo.

The chemical composition of different animal bones was studied using Raman spectroscopy and fluorescence spectroscopy. Using a luminescence spectrometer, the fluorescence spectra from an excitation of 300 nm, 340 nm, 400 nm and 500 nm were investigated and showed the key molecular components of bone. After 300 nm excitation, 380 nm fluorescence was seen, consistent with the presence of collagen. After 340 nm excitation, 380 nm fluorescence was seen, consistent with the presence of collagen, the main organic material in bone. An excitation of 340 nm also showed a fluorescence of 450 nm, most likely due to the presence of NADH. After 500 nm excitation, 600 nm fluorescence was seen, most likely caused by porphyrins due to blood within the bone. Raman spectroscopy using a 785 nm laser was also performed. With these spectroscopic tools, the important features and components of bone can be studied.

In most of medical and dental laser treatments, high power pulsed laser have been used as desirable light sources employing with an optical fiber delivery system. The treatment process involves high temperature thermal effect associated with direct laser absorption of the materials such as hard and soft tissues, tooth, bones and so on. Such treatments sometimes face technical difficulties suffering from their optical absorption properties. We investigate a new technology to create high temperature heat source on the tip surface of the glass fiber proposed for the medical surgery applications. Using a low power level (4~6W) semiconductor laser at a wavelength of 980nm, a laser coupled fiber tip was pre-processed to contain certain amount of TiO₂ powder with a depth of 400μm from the tip surface so that the irradiated low laser energy could be perfectly absorbed to be transferred to thermal energy. Thus the laser treatment can be performed without suffering from any optical characteristic of the material. Semiconductor laser was operated quasi-CW mode pulse time duration of 180ms and more than 95% of the laser energy was converted to thermal energy in the fiber tip. by Based on twocolor thermometry by using a gated optical multichannel analyzer with 0.25m spectrometer in visible wavelength region, the temperature of the fiber tip was analyzed. The temperature of the heat source was measured to be approximately 3000K. Demonstration of laser processing employing this system was successfully carried out drilling through holes in ceramic materials simulating bone surgery.

Introduction: In recent years, advances in technology are propelling the field of oral and maxillofacial surgery into new realms. With a relatively thin alveolar mucosa overlying the underlying bone, significant diagnostic and therapeutic advantages are present. However, there remains an enormous gap between advancements in physics, in particular optics, and oral and maxillofacial surgery.
Bone Pathology: Improvements in diagnosis, classification, and treatment of the various bone pathologies are still being sought after as advancements in technology continue to progress. Combining the clinical, histological, and pathological characteristics with these advancements, patients with debilitating pathologies may have more promising treatment options and prognosis.
Bone Grafting: Defects in the facial bones, in particular the jaws, may be due to a number of reasons: pathology, trauma, infections, congenital deformities, or simply due to atrophy. Bone grafting is commonly employed to correct such defects, and allows new bone formation through tissue regeneration.
Osseointegration: Growing use of dental implants has focused attention on osseointegration and its process. Osseointegration refers to the actual process of the direct contact between bone and implant, without an intervening soft tissue layer. The theories proposed regarding this process are many, yet there lacks a clear, unified stance on the actual process and its mechanisms. Further investigation using optical probes could provide that unifying answer.
Conclusion: The primary goal of this lecture is to introduce pioneers in the field of optics to the field of oral and maxillofacial surgery. With a brief introduction into the procedures and techniques, we are hopeful to bridge the ever-widening gap between the clinical science and the basic sciences.

Flashlamp pumped Er:YAG-lasers are successfully clinically used for both precise soft and hard tissue ablation. As an alternative, actually a novel diode pumped Er:YAG laser system (Pantec Engineering AG) becomes available, with mean laser power up to 15W and pulse repetition rate up to 1kHz. The aim of the presented study is to investigate the effect of this laser system on bone tissue at various irradiation parameters, particular at repetition rates exceeding 100 Hz. For reproducible experiments, firstly an appropriate experimental set-up was realized with a beam delivery and focusing unit, a computer controlled stepper unit with sample holder, and a shutter unit. It allowed to move the sample (1mm- 3mm sawed slices of pig bone) with a defined velocity while irradiation by various laser parameters. A water spray served to moisten the sample surfaces. After irradiation the grooves were analyzed by light microscopy and laser scanning microscopy regarding to the ablation quality, the groove geometry, the ablation efficacy, and the thermal effects. The resulting grooves are slightly cone shaped (groove depth up to 3mm, width about 200μm) with sharp edges at the surface. At 1W, 200Hz, 5mm/s sample movement and with water irrigation the measured ablation speed Δz/Δt is 10.8 mm/s. The ablation depth per pulse is 54μm. In conclusion, these first experiments demonstrate that the diode pumped Er:YAG laser system is an efficient tool for use in bone surgery.

Several laser systems in the infrared wavelength range, such as Nd:YAG, Er:YAG or CO₂ lasers are used for efficient ablation of bone tissue. Here the application of short pulses in coaction with a thin water film results in reduced thermal side effects. Nonetheless up to now there is no laser-process for bone cutting in a clinical environment due to lack of ablation efficiency. Investigations of laser ablation rates of bone tissue using a rinsing system and concerning bleedings have not been reported yet. In our study we investigated the ablation rates of bovine cortical bone tissue, placed 1.5 cm deep in water under laminar flow conditions, using a short pulsed (25 ps), frequency doubled (532 nm) Nd:YVO₄ laser with pulse energies of 1 mJ at 20 kHz repetition rate. The enhancement of the ablation rate due to debris removal by an additional water flow from a well-directed blast pipe as well as the negative effect of the admixture of bovine serum albumin to the water were examined. Optical Coherence Tomography (OCT) was used to measure the ablated volume. An experimental study of the depth dependence of the ablation rate confirms a simplified theoretical prediction regarding Beer-Lambert law, Fresnel reflection and a Gaussian beam profile. Conducting precise incisions with widths less than 1.5 mm the maximum ablation rate was found to be 0.2 mm³/s. At depths lower than 100 μm, while the maximum depth was 3.5 mm.

Introduction: In the field of oral and maxillofacial surgery, there are many applications for lasers and optics. The first part of this manuscript is to discuss laser therapy and garner suggestions on how it can be improved. The second part is to present a case in which complications of a bone graft delayed healing and a return to normalcy for the patient. It is the goal of this paper to utilize the new advancements in optics so that patient care can be improved. Laser Therapy: Laser ablation and low-level laser therapy have been used in a variety of joint adhesion cases, including arthritis of the hand and foot. In the field of oral and maxillofacial surgery, this method has been used to treat pain and mobility dysfunction in patients with temporomandibular joint disease. While the outcomes have been promising, lack of familiarity with the device or doubt about its effects have reduced its use. This reduction in use has left the actual process of laser therapy relatively unchanged. Case Presentation: A 28 year-old female presented for a mandibular resection due to an ossifying fibroma. In the next several months her reconstructed area displayed significant signs of infection, as well as graft failure. X-rays, unfortunately, did not display the actual metabolic activity. Although the patient was reconstructed successfully thereafter, with more advanced technology available the patient could have endured a more comfortable treatment. Conclusion: While there are many more areas of oral and maxillofacial surgery that could potentially benefit from advances in optical technology, we have chosen to highlight these two areas due to their prevalence within our community.

Osteoporosis is a major health problem worldwide, with healthcare costs of billions of dollars annually. The risk of fracture depends on the bone mineral density (measured in clinical practice) as well as on the bone microstructure and functional status. Since pure ultrasonic methods can measure bone strength and spectroscopic optical methods can provide valuable functional information, a hybrid multispectral photoacoustic technique can be of great value. We have developed such a system based on a tunable Ti:Sapph laser at 750 - 950 nm, followed by an acousto-optic modulator to generate photoacoustic signals with frequencies of 0.5 - 2.5 MHz. Another system was based on two directly modulated 830nm laser diodes. The systems were used to photoacoustically excite the proximal end of a rat tibia. Spectrum analyzer with tracking generator was used for measuring both the amplitude and the phase at the distal end. Scanning along both the optical wavelength as well as the acoustic frequency enables full mapping of the bone transfer function. Analyzing this function along the wavelength axis allows deducing the gross biochemical composition related to the bone functional and pathological state. Analyzing the amplitude and phase along the acoustic frequency axis yields the speed of sound dispersion and the broadband ultrasonic attenuation - both have shown clinical relevance.

A zebrafish model has recently been introduced to study various genetic mutations that could lead to spinal deformities such as scoliosis. However, current imaging techniques make it difficult to perform longitudinal studies of this condition in zebrafish, especially in the early stages of development. The goal of this project is to determine whether optical coherence tomography (OCT) is a viable non-invasive method to image zebrafish exhibiting spinal deformities. Images of both live and fixed malformed zebrafish (5 to 21 days postfertilization) as well as wild-type fish (5 to 29 days postfertilization) were acquired non-invasively using a commercial SD-OCT system, with a laser source centered at 930nm (λ=100nm), permitting axial and lateral resolutions of 7 and 8μm respectively. Using two-dimensional images and three-dimensional reconstructions, it was possible to identify the malformed notochord as well as deformities in other major organs at different stages of formation. Visualization of the notochord was facilitated with the development of a segmentation algorithm. OCT images were compared to HE histological sections and images obtained by calcein staining. Because of the possibility of performing longitudinal studies on a same fish and reducing image processing time as compared with staining techniques and histology, the use of OCT could facilitate phenotypic characterization in studying genetic factors leading to spinal deformities in zebrafish and could eventually contribute to the identification of the genetic causes of spinal deformities such as scoliosis.

This study examines the application of backscattered ultrasound (US) and photoacoustics (PA) for assessment of bone structure and density variations. Both methods are applied in the frequency-domain, employing linear frequency modulation chirps. An 800-nm CW laser and a 3.5-MHz ultrasonic transducer are used for transmitting the signal. The backscattered pressure waves are detected with a 2.2-MHz US transducer. Experiments are focused on detection and evaluation of PA and US signals from in-vitro animal and human bones with cortical and trabecular sublayers. Osteoporotic changes in the bone are simulated by using a very mild demineralization solution (EDTA). Changes in the time-domain signal as well as integrated backscattering spectra are compared for each sample before and after demineralization. Results show the ability of US to generate detectable signals from deeper bone sublayers, whereas the PA signals show higher sensitivity to the variation in bone density. While US signal variation with changes in the cortical layer is insignificant, PA has proven to be able to detect minor variation of the cortical bone density.

Raman spectroscopy can non-destructively measure properties of bone related to mineral density, mineral composition, and collagen composition. Bone properties can be measured through the skin in animal and human subjects, but correlations between the transcutaneous and exposed bone measurements have only been reported for human cadavers. In this study, we examine human subjects to collect measurements transcutaneously, on surgically exposed bone, and on recovered bone fragments. This data will be used to demonstrate in vivo feasibility and to compare transcutaneous and exposed Raman spectroscopy of bone. A commercially available Raman spectrograph and optical probe operating at 785 nm excitation are used for the in vivo measurements. Requirements for applying Raman spectroscopy during a surgery are also discussed.

Activation Transcription Factor 4 (Atf-4) is essential for osteoblast maturation and proper collagen synthesis. We recently found that these bones demonstrate a rare brittleness phenotype, which is independent of bone strength. We utilized a confocal Renishaw Raman microscope (50x objective; NA=.75) to evaluate embedded, polished cross-sections of mouse tibia from both wild-type and knockout mice at 8 weeks of age (24 mice, n<=8 per group). Analysis of peak ratios indicated statistically significant changes in both mineral and collagen; however, compositional changes did not fully encompass biomechanical differences. To investigate the impact of material organization, we acquired colocalized spectra aligning the polarization angle parallel and perpendicular to the long bone axis from wet intact femurs. To validate our results, we used MMP9-/- mice, which have a brittleness phenotype that is not explained by compositional Raman measures. Polarization angle difference spectra show marked significant changes in orientation of these compositional differences when comparing wild type to knockout bones. Relative to wild-type, Atf4 -/- and MMP9 -/- bones show significant differences (t-test; p<0.05) in prominent collagen peaks. Further investigation of known peak ratios illustrates that this physical anisotropy of molecular organization is tightly clustered in brittle knockout bones. Such findings could have alternate interpretations about net collagen orientation or the angular distribution of collagen molecules. Use of polarization specific Raman measurements has implicated a structural profile that furthers our understanding of models of bone brittleness. Polarization content of Raman spectra may prove significant in future studies of brittle fracture and human fracture risk.

Precision depth control of bone resection is necessary for safe surgical procedures in the spine. In this paper, we compare the control and quality of cutting bovine tail bone, as an ex vivo model of laminectomy and bony resection simulating spinal surgery, planned with micro-CT data and executed using two approaches: (a) mechanical milling guided by optical topographical imaging (OTI) and (b) optical milling using closed-loop inline coherent imaging (ICI) to monitor and control the incision depth of a high-power 1070 nm fiber laser in situ. OTI provides the in situ topology of the 2-dimensional surface of the bone orientation in the mechanical mill which is registered with the treatment plan derived from the micro-CT data. The coregistration allows the plan to be programmed into the mill which is then used as a benchmark of current surgical techniques. For laser cutting, 3D optical land marking with coaxial camera vision and the ICI system is used to coregister the treatment plan. The unstable, carbonization-mediated ablation behaviour of 1070 nm light and the unknown initial geometry of bone leads to unpredictable ablation which substantially limits the depth accuracy of open-loop cutting. However, even with such a non-ideal cutting laser, we demonstrate that ICI provides in situ high-speed feedback that automatically and accurately limits the laser’s cut depth to effectively create an all-optical analogue to the mechanical mill.

Metastatic cancer causes the majority of tumors in bone, most frequently detected in the spinal column. Skeletal complications cause pain and neurologic impairment. Photodynamic therapy (PDT) has been used to treat a variety of cancers. Minimally invasive surgical (MIS) strategies may allow targeted light application essential for PDT within bone structures. The purpose of this manuscript is to provide an update on pre-clinical status as well as early clinical experience of a Phase I clinical trial on vertebral PDT.

A pre-clinical (rnu/rnu rat) vertebral metastasis model of osteolytic (MT-1 breast cancer) was optimized and used to evaluate the effect of vertebral PDT. PDT alone and in combination with other standard local (radiation therapy, RT) and systemic (bisphosphonates, BP) therapies was evaluated through bioluminescence imaging, micro-CT based stereology, histology, and biomechanical testing. Single PDT treatment (photosensitizer BPD-MA, 690nm light) ablated tumor tissue in targeted vertebrae. PDT led to significant increases in bone structural properties, with greatest benefits observed from combined BP+PDT therapy: 76% and 19% increases in bone volume fraction in treated tumor-bearing and healthy untreated controls, respectively. Similar synergistic improvements (but of lesser magnitude) were found in combined PDT+RT treatments.

The safety and feasibility of MIS+PDT were evaluated in scale-up animal studies, refining surgical technique for clinical translation. Following appropriate institutional review board as well as Health Canada approval, 5 patients (light only control group) have undergone protocoled treatment to date. These patients have guided further refinement of human therapeutic application from a laser delivery and vertebral bone access perspective.