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- Front Matter: Volume 8926
- Optical Monitoring of Wounds
- Confocal Microscopy
- Optical Spectroscopy
- Photodynamic Therapy
- Optical Microscopy and Optical Coherence Tomography
- Model-Based Analysis of Optical Data
- Wide-Field Functional Imaging
- Poster Session
- Tissue Imaging I
- Tissue Therapeutics
- Laser Lithotripsy
- Tissue Imaging II
- Advanced Imaging and Novel Treatment Strategies in Otology
- OCT for Functional Laryngeal Imaging
- Basic Research and Engineering Concepts for Avanced Head and Neck Imaging
- Practical Results of Novel Imaging Technology in Head and Neck Lesions
- PDT and Related Technology for Malignant and Pre-Malignant Head and Neck Lesions
- Current Concepts in Laser Surgery and Optical Tracking
- Upper Airway OCT and Spectroscopy
- Spectroscopy
- Myocardium and Therapy
- Light and Sound
- Poster Session
- Bone Surgery and Ablation
- Musculoskeletal Imaging and Diagnostics I
- Musculoskeletal Imaging and Diagnostics II
- Bone Spectroscopy and Surgery
Front Matter: Volume 8926
Front Matter: Volume 8926
Show abstract
This PDF file contains the front matter associated with SPIE Proceedings Volume 8926, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.
Optical Monitoring of Wounds
Irradiation with EMOLED improves the healing process in superficial skin wounds
Show abstract
A faster healing process was observed in superficial skin wounds after irradiation with the EMOLED photocoagulator.
The instrument consists of a compact handheld photocoagulation device, useful for inducing coagulation in superficial
abrasions. The illumination is provided by a high power blue LED. Blue light is selectively absorbed by haemoglobin
and converted into heat through a photothermal effect. In this study, 10 Sprague Dawley rats were mechanically abraded
in four regions of their back: two regions were used as a control and the other two were treated with EMOLED. The
photothermal effect was monitored by an infrared thermocamera in order to avoid accidental thermal damage. Visual
observations, histopathological analysis and non-linear microscopic imaging performed after 8 days from the treatment
showed no adverse reactions and no thermal damage in both treated areas and surrounding tissues. Moreover, a faster
healing process and a better-recovered morphology was evidenced in the treated tissue with respect to the untreated
tissue. Compared to the control regions, a reduced inflammatory response, a higher collagen content, and a skin
morphology more similar to normal skin were observed in the treated regions. Collagen organization in the two regions
was characterized using image pattern analysis algorithms on SHG images, demonstrating a fully recovered aspect of
dermis as well as a faster neocollagenesis in the treated regions. This study demonstrates that the selective photothermal
effect we used for inducing immediate coagulation in superficial wounds is associated to a minimal inflammatory
response, which provides reduced recovery times and improved healing process.
Monitoring the influence of compression therapy on pathophysiology and structure of a swine scar model using multispectral imaging system
Show abstract
Scar contractures can lead to significant reduction in function and inhibit patients from returning to work, participating in leisure activities and even render them unable to provide care for themselves. Compression therapy has long been a standard treatment for scar prevention but due to the lack of quantifiable metrics of scar formation scant evidence exists of its efficacy. We have recently introduced a multispectral imaging system to quantify pathophysiology (hemoglobin, blood oxygenation, melanin, etc) and structural features (roughness and collagen matrix) of scar. In this study, hypertrophic scars are monitored in-vivo in a porcine model using the imaging system to investigate influence of compression therapy on its quality.
Hyperspectral characterization of an in vitro wound model
Show abstract
Wound healing is a complex process not fully understood. There is a need of better methods to evaluate the different stages of healing, and optical characterization is a promising tool in this respect.
In this study hyperspectral imaging was employed to characterize an in vitro wound model.
The wound model was established by first cutting circular patches of human abdominal skin using an 8mm punch biopsy tool, and then creating dermal wounds in the center of the skin patches using a 5mm tool. The wounds were incubated in medium with 10% serum and antibiotics. Hyperspectral images were collected every three days using a push broom hyper spectral camera (Hyspex VNIR1600). The camera had a spectral resolution of 3.7 nm and was fitted with a close up lens giving a FOV of 2.5 cm and a spatial resolution of 29 micrometer. Samples for histology were collected throughout the measurement period, which was 21 days in total. Data were processed in ENVI and Matlab.
A successful classification based on hyperspectral imaging of the implemented model is presented. It was not possible to see the healing zone in the in vitro model with the naked eye without dying. The hyperspectral results showed that newly formed epithelium could be imaged without any additional contrast agents or dyes. It was also possible to detect non-viable tissue. In vitro wound models and hyperspectral imaging can thus be employed to gain further insight in the complicated process of healing in different kinds of wounds.
Prognostic prospective of laser induced fluorescence as an objective tool to evaluate collagen deposition in thermal wounds: an ex vivo study
Show abstract
We aimed to investigate the predicative potential of laser induced fluorescence (LIF) in assessing collagen synthesis during wound healing progression following thermal injury. Granulation tissues of thermal wounds before grafting were collected and LIF measurements were carried out by exciting them with 325 nm to measure collagen. Biochemical estimation of the hydroxyproline was also carried out. Spectroscopic assessment & biochemical estimation of the wound granulation tissues displayed varied collagen levels. It can be concluded that LIF has the potential to be used as an objective tool to qualitatively determine the collagen levels in wound granulation tissues.
Confocal Microscopy
Feasibility of intraoperative imaging during Mohs surgery with reflectance confocal microscopy
Show abstract
Mohs surgery for the removal of non-melanoma skin cancers (NMSCs) is performed in stages, while being guided by the examination for residual tumor with frozen pathology. However, preparation of frozen pathology at each stage is timeconsuming and labor-intensive. Real-time intraoperative reflectance confocal microscopy (RCM) may enable rapid detection of residual tumor directly in surgical wounds on patients. We report initial feasibility on twenty-one patients, using 35% AlCl3 for nuclear contrast. Imaging was performed in quadrants in the wound, to simulate the Mohs surgeon’s examination of pathology. Images and videos of the epidermal and dermal margins were found to be of clinically acceptable quality. Bright nuclear morphology was identified at the epidermal margin. The presence of residual BCC/SCC tumor and normal skin features could be detected in the peripheral and deep dermal margins. Nuclear morphology was detectable in residual BCC/SCC tumors. Intraoperative RCM imaging may enable detection of residual tumor, directly on Mohs patients, and may serve as an adjunct for frozen pathology. However, a stronger source of contrast will be necessary, and also a smaller device with an automated approach for imaging in the entire wound in a rapid and controlled manner for clinical utility.
Optical Spectroscopy
Sensing vascularization of ex-vivo produced oral mucosal equivalent (EVPOME) skin grafts in nude mice using optical spectroscopy
Show abstract
Repair of soft tissue defects of the lips as seen in complex maxillofacial injuries, requires pre-vascularized multi-tissue
composite grafts. Protocols for fabrication of human ex-vivo produced oral mucosal equivalents (EVPOME) composed
of epithelial cells and a dermal equivalent are available to create prelaminated flaps for grafting in patients. However, invivo
assessment of neovascularization of the buried prelaminated flaps remains clinically challenging. Here, we use
diffuse reflectance spectroscopy (DRS) and diffuse correlation spectroscopy (DCS) to non-invasively quantify
longitudinal changes in the vessel density and blood-flow within EVPOME grafts implanted in the backs of SCID mice
and subsequently to determine the utility of these optical techniques for assessing vascularization of implanted grafts. 20
animals were implanted with EVPOME grafts (1x1x0.05 cm3) in their backs. DRS and DCS measurements were
obtained from each animal both atop the graft site and far away from the graft site, at one week post-implantation, each
week, for four consecutive weeks. DRS spectra were analyzed using an inverse Monte Carlo model to extract tissue
absorption and scattering coefficients, which were then used to extract blood flow information by fitting the
experimental DCS traces. There were clear differences in the mean optical parameters (averaged across all mice) at the
graft site vs. the off-site measurements. Both the total hemoglobin concentration (from DRS) and the relative blood flow
(from DCS) peaked at week 3 at the graft site and declined to the off-site values by week 4. The optical parameters
remained relatively constant throughout 4 weeks for the off-site measurements.
Comparison of cone and cone shell configuration for depth sensitive fluorescence measurements in turbid media
Show abstract
We have developed a novel cone shell illumination and detection configurations using combination of axicon lenses for
depth sensitive fluorescence spectroscopy. The probe was demonstrated experimentally to be able to selectively
detecting fluorescence from different depths from a two-layered turbid agar phantom. In addition to enhanced contrast of
subsurface fluorescence measurement as compared to a conventional cone configuration implemented by a microscope
objective lens, the axicon lenses based setup eliminated the need of moving the objective lens up or down to achieve
depth sensitive measurements, which effectively improves the consistency of optical coupling thus would be preferred in
a clinical setting.
Photodynamic Therapy
Photodynamic therapy improves the ultraviolet-irradiated hairless mice skin
Show abstract
Chronic exposure to ultraviolet (UV) sunlight causes premature skin aging. In light of this fact, photodynamic therapy
(PDT) is an emerging modality for treating cancer and other skin conditions, however its response on photoaged skin has
not been fully illustrated by means of histopathology. For this reason, the aim of this study was analyze whether PDT can
play a role on a mouse model of photoaging. Hence, SKH-1 hairless mice were randomly allocated in two groups, UV
and UV/PDT. The mice were daily exposed to an UV light source (280-400 nm: peak at 350 nm) for 8 weeks followed
by a single PDT session using 20% 5-aminolevulinic acid (ALA) topically. After the proper photosensitizer
accumulation within the tissue, a non-coherent red (635 nm) light was performed and, after 14 days, skin samples were
excised and processed for light microscopy, and their sections were stained with hematoxylin-eosin (HE) and Masson’s
Trichrome. As a result, we observed a substantial epidermal thickening and an improvement in dermal collagen density
by deposition of new collagen fibers on UV/PDT group. These findings strongly indicate epidermal and dermal
restoration, and consequently skin restoration. In conclusion, this study provides suitable evidences that PDT improves
the UV-irradiated hairless mice skin, supporting this technique as an efficient treatment for photoaged skin.
Optical Microscopy and Optical Coherence Tomography
High resolution in-vivo imaging of skin with full field optical coherence tomography
Show abstract
Full-field OCT (FFOCT) has the ability to provide en-face images with a very good axial sectioning as well as a very
high transverse resolution (about 1 microns in all directions). Therefore it offers the possibility to visualize biological
tissues with very high resolution both on the axial native view, and on vertical reconstructed sections. Here we
investigated the potential dermatological applications of in-vivo skin imaging with FFOCT.
A commercial FFOCT device was adapted for the in-vivo acquisition of stacks of images on the arm, hand and finger.
Several subjects of different benign and pathological skin conditions were tested. The images allowed measurement of
the stratum corneum and epidermis thicknesses, measurement of the stratum corneum refractive index, size measurement
and count of the keratinocytes, visualization of the dermal-epidermal junction, and visualization of the melanin granules
and of the melanocytes. Skins with different pigmentations could be discriminated and skin pathologies such as eczema
could be identified.
The very high resolution offered by FFOCT both on axial native images and vertical reconstructed sections allows for
the visualization and measurement of a set of parameters useful for cosmetology and dermatology. In particular, FFOCT
is a potential tool for the understanding and monitoring of skin hydration and pigmentation, as well as skin inflammation.
Model-Based Analysis of Optical Data
Estimation of skin optical parameters for real-time hyperspectral imaging applications
Show abstract
Hyperspectral imaging combines high spectral and spatial resolution in one modality. This imaging technique is a promising tool for objective medical diagnostics. However, to be attractive in a clinical setting the technique needs to be fast and accurate. Hyperspectral imaging can be used to analyze the chemical composition of tissue using spectroscopic methods, and is thus useful as a general purpose diagnostic tool. In this study, we combine an analytic diffusion model for photon transport with real-time analysis of hyperspectral images. This is achieved by inverting and parallelizing the photon transport model on a GPU to yield optical parameters from diffuse reflectance spectra. The resulting inversion chain was found to output the results in real-time. The inverse approach was found to characterize the relative differences in the optical properties. The presented approach is a proof of principle, necessary for developing a future real-time diagnostic system using hyperspectral imaging.
Quantitative fluorescence molecular imaging in highly light-absorbing melanomas using a dual-tracer kinetic modeling normalization method
Show abstract
Tissues with high light absorption, such as melanomas, present a significant challenge to fluorescence imaging
approaches that seek to estimate molecular expression in vivo, since any fluorescence originating in the tissue will suffer
substantial attenuation prior to detection. This can lead to sizable underestimations in estimated fluorescent tracer
concentration in these tissues using conventional fluorescence imaging. In this study, a dual-tracer fluorescence imaging
approach was employed to correct for severe tissue absorption by 1) using simultaneous injection and imaging of an
untargeted tracer to normalize tissue absorption effects on the targeted tracer, and 2) using kinetic modeling that
capitalizes on subtle differences in the dynamics of targeted and untargeted tracer uptake to quantify targeted molecule
concentrations in the high absorbing tissue. Monte Carlo simulation and kinetic models demonstrated that the effect of
optical properties on the approach could be eliminated by a pixel-by-pixel normalization of the targeted and untargeted
tracer uptakes prior to 5 min post-tracer injection for fluorescence planar dynamic imaging.
Combining the diffusion approximation and Monte Carlo modeling in analysis of diffuse reflectance spectra from human skin
Show abstract
Light propagation in highly scattering biological tissues is often treated in the so-called diffusion approximation (DA).
Although the analytical solutions derived within the DA are known to be inaccurate near tissue boundaries and absorbing
layers, their use in quantitative analysis of diffuse reflectance spectra (DRS) is quite common. We analyze the artifacts in
assessed tissue properties which occur in fitting of numerically simulated DRS with the DA solutions for a three-layer
skin model. In addition, we introduce an original procedure which significantly improves the accuracy of such an inverse
analysis of DRS. This procedure involves a single comparison run of a Monte Carlo (MC) numerical model, yet avoids
the need to implement and run an inverse MC. This approach is tested also in analysis of experimental DRS from human
skin.
Monte Carlo modeling of pigmented lesions
Show abstract
Colors observed in clinical dermoscopy are critical to diagnosis but the mechanisms that lead to the spectral components of diffuse reflectance are more than meets the eye: combinations of the absorption and scattering spectra of the biomolecules as well as the “structural color” effect of skin anatomy. We modeled diffuse remittance from skin based on histopathology. The optical properties of the tissue types were based on the relevant chromophores and scatterers. The resulting spectral images mimic the appearance of pigmented lesions quite well when the morphology is mathematically derived but limited when based on histopathology, raising interesting questions about the interaction between various wavelengths with various pathological anatomical features.
Enhanced diagnostic of skin conditions by polarized laser speckles:
phantom studies and computer modeling
Show abstract
The incidence of the skin melanoma, the most commonly fatal form of skin cancer, is increasing faster than any other
potentially preventable cancer. Clinical practice is currently hampered by the lack of the ability to rapidly screen the
functional and morphological properties of tissues. In our previous study we show that the quantification of scattered
laser light polarization provides a useful metrics for diagnostics of the malignant melanoma. In this study we exploit
whether the image speckle could improve skin cancer diagnostic in comparison with the previously used free-space
speckle. The study includes skin phantom measurements and computer modeling. To characterize the depolarization of
light we measure the spatial distribution of speckle patterns and analyse their depolarization ratio taken into account
radial symmetry. We examine the dependences of depolarization ratio vs. roughness for phantoms which optical
properties are of the order of skin lesions. We demonstrate that the variation in bulk optical properties initiates the
assessable changes in the depolarization ratio. We show that image speckle differentiates phantoms significantly better
than free-space speckle. The results of experimental measurements are compared with the results of Monte Carlo
simulation.
Wide-Field Functional Imaging
Tumor site prediction using spatiotemporal detection of subclinical hyperemia in experimental photocarcinogenesis
Show abstract
We demonstrate that a spatial and temporal analysis of subclinical hyperemia reliably predicts specific areas at high risk
for skin tumor development during photocarcinogenesis. To determine detailed spatiotemporal patterns of inflammatory
angiogenesis foci in a relatively large area, we developed a mesoscopic (between microscopic and macroscopic) imaging
approach. This method relies on our earlier finding that the combination of a spectral analysis of hemoglobin with
diffuse-light-suppressed imaging can increase the image resolution, contrast and penetration depth to visualize
microvasculature Hgb content in the large tissue area. In our recent study, SKH1 hairless albino mice were irradiated
for 10 weeks with a carcinogen dose of UVB. Using our newly developed mesoscopic imaging methods, we imaged
the mice over 20 - 30 weeks after stopping UVB, and excised hyperemic/non-hyperemic areas at several different timepoints.
We show that persistent hyperemic foci can predict future tumor formation. In particular, our imaging approach
allows us to assess the spatial and temporal extent of subclinical inflammatory foci, which in turn can predict sites of
future overlying tumor formation. In addition, although COX-2 inhibitors are known to suppress skin cancer
development in humans, it remains unclear whether the chemopreventive activity of COX-2 inhibitors are chiefly
attributable to their anti-inflammatory effects. Our study provides evidence that subclinical subepithelial inflammatory
foci occur prior to overt tumor formation, and that these areas are highly predictive for future tumor formation, that
celecoxib’s ability to suppress tumorigenesis is tightly linked to its ability to reduce the area of subclinical inflammatory
foci.
Hyperspectral imaging for melanoma screening
Show abstract
The 5-year survival rate for patients diagnosed with Melanoma, a deadly form of skin cancer, in its latest
stages is about 15%, compared to over 90% for early detection and treatment. We present an imaging
system and algorithm that can be used to automatically generate a melanoma risk score to aid clinicians in
the early identification of this form of skin cancer. Our system images the patient's skin at a series of
different wavelengths and then analyzes several key dermoscopic features to generate this risk score. We
have found that shorter wavelengths of light are sensitive to information in the superficial areas of the skin
while longer wavelengths can be used to gather information at greater depths. This accompanying
diagnostic computer algorithm has demonstrated much higher sensitivity and specificity than the currently
commercialized system in preliminary trials and has the potential to improve the early detection of
melanoma.
Poster Session
Microneedles rollers as a potential device to increase ALA diffusion and PpIX production: evaluations by wide-field fluorescence imaging and fluorescence spectroscopy
Show abstract
One of the limitations of topical photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) is the poor ability to penetrate biological barriers of skin and the recurrence rates in treatments. This study aimed to identify possible signs of increased diffusion of ALA-induced PpIX by fluorescence images and fluorescence spectroscopy. The research was done using in vivo porcine skin model. Before the cream application, microholes was performed with microneedles rollers in only one direction, afterward the ALA cream was applied at a 2.5cm2 area in triplicate and an occlusive dressing was placed. PpIX production was monitored using fluorescence spectroscopy collected at skin surface after 70, 100, 140, and 180 minutes of ALA incubation. About 100 fluorescence spectra of each treatment were collected, distributed by about five points for each site. Wide-field fluorescence imaging was made after 70, 90, and 170 minutes after treatment. The results obtained by imaging analysis indicated increase of the PpIX diffusion in the skin surface using the microneedles rollers (MNs) before ALA application. Circular regions of red fluorescence around the microholes were observed. In addition, the fluorescence spectra showed a greater intensity (2 times as many) in groups microneedles rollers associated. In conclusion, our data shown greater homogeneity and PpIX production in the groups pre-treated with microneedles indicating that the technique can be used to greater uniformity of PpIX production throughout the area to be treated reducing the chances of recurrent tumor as well as has potential for decreasing the time of therapy. (FUNDING SUPPORT:CAPES, CNPq and FAPESP)
Tissue Imaging I
Optical diagnosis of testicular torsion: feasibility and methodology
Show abstract
Background: Torsion of the testis compromises blood flow through the spermatic cord; testicular ischemia results which if not diagnosed promptly and corrected surgically irrevocably damages the testis. Current diagnostic modalities aimed at rationalizing surgical exploration by demonstrating interruption of spermatic cord blood flow or testicular ischemia have limited applicability. Near infrared spectroscopy (NIRS) offers a non-invasive optical method for detection of ischemia; continuous wave and frequency domain devices have been used experimentally; no device customized for clinical use has been designed. Methods: A miniature spatially resolved NIRS device with light emitting diode light source was applied over the right and left spermatic cord and the difference in oxygen saturation between the two sides measured. Results: In a 14-month old boy with a history of unilateral testicular pain color Doppler ultrasonography was equivocal but the NIRS-derived tissue oxygen saturation index (TSI) was significantly reduced on the left side. Confirmation of torsion of the left testicle was made surgically. Conclusions: Spatially resolved NIRS monitoring of spermatic cord oxygen saturation is feasible in children, adding to prior studies of testicular oxygen saturation in adults. Customized device design and further clinical trials would enhance the applicability of NIRS as a diagnostic entity for torsion.
Tissue Therapeutics
Rapid infrared laser sealing and cutting of porcine renal vessels, ex vivo
Show abstract
Suture ligation with subsequent cutting of blood vessels to maintain hemostasis during surgery is time consuming
and skill intensive. Energy-based, electrosurgical and ultrasonic devices are often used to replace sutures and
mechanical clips to provide rapid hemostasis, and decrease surgical time. Some of these devices may create
undesirably large collateral zones of thermal damage and tissue necrosis, or require separate mechanical blades for
cutting. Infrared lasers are currently being explored as alternative energy sources for vessel sealing applications. In
a previous study, a 1470-nm laser was used to seal vessels of 1-6 mm in diameter in 5 s, yielding burst pressures of
~ 500 mmHg. The purpose of this study was to provide faster sealing, incorporate transection of the sealed vessels,
and increase the burst pressure. A 110-Watt, 1470-nm laser beam was transmitted through a fiber and beam shaping
optics, producing a linear beam 3.0 mm by 9.5 mm for sealing, and 1.1 mm by 9.6 mm for cutting (FWHM). A twostep
process sealed then transected ex vivo porcine renal vessels (1-8.5 mm diameter) in a bench top setup. Seal and
cut times were 1.0 s each. A standard burst pressure system measured resulting seal strength, and gross and
histologic thermal damage measurements were also recorded. All blood vessels tested (n = 30) were sealed and cut,
with total irradiation times of 2.0 s, mean burst pressures > 1000 mmHg (compared to normal systolic blood
pressure of 120 mmHg), and combined seal/collateral thermal coagulation zones of 2-3 mm. The results of this
study demonstrated that an optical-based system is capable of precisely sealing and cutting a wide range of porcine
renal vessel sizes, and with further development, may provide an alternative to radiofrequency and ultrasound-based
vessel sealing devices.
Blood coagulation using High Intensity Focused Ultrasound (HIFU)
Show abstract
High Intensity Focused Ultrasound (HIFU) technology provides a feasible method of achieving thermal coagulation during surgical procedures. One of the potential clinical benefits of HIFU can induce immediate hemostasis without suturing. The objective of this study was to investigate the efficiency of a HIFU system for blood coagulation on severe vascular injury. HIFU treatment was implemented immediately after bleeding in artery. The ultrasound probe was made of piezoelectric material, generating a central frequency of 2.0 MHz as well as an ellipsoidal focal spot of 2 mm in lateral dimension and 10 mm in axial dimension. Acoustic coagulation was employed on a perfused chicken artery model in vitro. A surgical incision (1 to 2 mm long) was made with a scapel on the arterial wall, and heparinized autologous blood was made to leak out from the incision with a syringe pump. A total of 5 femoral artery incisions was treated with the HIFU beam. The intensity of 4500 W/cm2 at the focus was applied for all treatments. Complete hemostasis was achieved in all treatments, along with the treatment times of 25 to 50 seconds. The estimated intraoperative blood loss was from 2 to 5 mL. The proposed HIFU system may provide an effective method for immediate blood coagulation for arteries and veins in clinical applications.
Ex vivo evaluation of safety and efficacy of vaporization of the prostate
using a 300 W high-power laser diode with the wavelength of 980 nm
Show abstract
Laser vaporization of the prostate is one of the promising technique for less-invasive treatment of benign prostatic
hyperplasia. However, shorter operative duration and higher hemostatic ability are expected. The wavelength of 980 nm
offers a high simultaneous absorption by water and hemoglobin, so that it combines the efficient vaporization with good
hemostasis. Therefore, we have evaluated the safety and efficacy of vaporization of the prostate using a recently
developed 300 W high-power laser diode with the wavelength of 980 nm. First, validity of bovine prostate tissue as the
sample was confirmed by measuring the optical properties of bovine and human prostate tissue using a double
integrating sphere optical system. Next, contact and non-contact ex vivo irradiations were performed for various
irradiation powers and times, and vaporized and coagulated depths were measured. In the contact irradiation, the
vaporized depth at the power of 300 W was significantly deeper than that at the power of 100 W, while the difference
was relatively smaller for the coagulated depths at 300 and 100 W. In the non-contact irradiation, coagulation as thick as
that in the contact irradiation was observed almost without vaporization. Therefore, it is suggested that the treatment in
the contact irradiation using the high-power laser diode can vaporize the prostate more efficiently without increasing the
risk of perforation. Hemostasis with the coagulation would be possible in both irradiation methods. To prevent the
postoperative perforation, operators need to understand the relationship between the coagulated depth and the irradiation
conditions.
Intraluminal occlusion of the seminal duct by laser and Histoacryl: Two non-invasive alternatives for vasectomy
Show abstract
Introduction and objective: Vasectomy is a well-established method in family control. Even though it is a safe and
low risk operation, this surgery is invasive and difficult to reverse. Therefore the aim of this study was to investigate
new non-invasive methods for occlusion of the seminal duct.
Material and Methods: Seminal duct tissue was obtained from patients (n=30) suffering from prostate cancer and
therefore undergoing prostatectomy. In a first set of experiments, the seminal duct was occluded by intraluminal
application of Histoacryl® (Braun Aesculap AG, Tuttlingen, Germany). In a 2nd set of experiments, endoluminal
laser induced occlusion was performed. Four different laser wavelengths (1940nm, 1470nm, 1064nm, 940nm) and
different sets of laser parameters (e.g. power, exposure duration, fibre diameter, energy applied) were compared.
Effectiveness of occlusion of the seminal duct was proven by post-treatment irrigation flow measurement, as well as
by morphological analyses. To evaluate a potential damage of the surrounding tissue, external temperature was
measured using a thermometer during laser application.
Results: Intraluminal application of Histoacryl® induced an immediate and complete occlusion of the seminal duct.
The underlying connective tissue maintained its functional integrity after this treatment. By laser light application to
a Histoacryl® block, a hole could be created into the block thus indicating the possibility of recanalization. Treatment
with laser energy resulted in shrinkage of the ductal lumen. The laser application generally caused necrosis in the
epithelium and induced formation of vacuoles in the underlying connective tissue. As described for endoluminal
varicose treatment, this distinct local reaction might result in an intense inflammation leading to a functional
occlusion of the vas deferens.
Conclusions: Both laser-induced occlusion and application of Histoacryl® are fast and simple techniques which may
be able to achieve a functional occlusion of the seminal duct. The application of Histoacryl® additionally may be
easily reversible by laser treatment.
Investigation on the smoke development during Laparoscopic surgery
Show abstract
Objective: During laser assisted laparoscopic intervention smoke occurs reducing the clear vision to the target. Simply
smoke suction is not possible with respect to deflating / enflating capabilities of the belly. Thus the clinical question arise
if the use of different wavelength may show similar smoke development or whether is it possible to reduce the smoke
development by wavelength selection.
Materials and Methods: Tissue test model was “Bavarian Leberkäse”. A special container set-up was created to collect
the laser induced smoke. Smoke was suctioned through a capillary. The amount of light scattered by the smoke particles
when flowing through this capillary was measured. Ablation parameter was continuous mode and10W at the end of a
400μm bare fibre for the wavelengths 980nm, 1350nm and 1470nm. Additional the optical transmission was measured.
The vaporized tissue volume was measured.
Results: Light scattering, optical parameters and vaporized tissue volume were correlated. Measurement showed
reproducible results. While the time to get first signal of scattered light in case of 1470nm is shorter compared the other
wavelength, the ratio of scatter-signal to ablation rate showed only a trend increase when longer wavelength were used.
Conclusion: Tissue absorbers and carbonized tissue properties are relevant for smoke development resulting in an
increased SI / AR ratio trend. Thus the expert physician in laparoscopic intervention should also be an expert in lasertissue
interaction. Cutting without carbonization gained advantages.
A compact, inexpensive infrared laser system for continuous-wave optical stimulation of the rat prostate cavernous nerves
William C. Perkins,
Gwen A. Lagoda,
Arthur L. Burnett M.D.,
et al.
Show abstract
Optical nerve stimulation (ONS) has been commonly performed in the laboratory using high-power, pulsed, infrared
(IR) lasers including Holmium:YAG, diode, and Thulium fiber lasers. However, the relatively high cost of these
lasers in comparison with conventional electrical nerve stimulation (ENS) equipment may represent a significant
barrier to widespread adoption of ONS. Optical stimulation of the prostate cavernous nerves (CN’s) has recently
been reported using lower cost, continuous-wave (CW), all-fiber-based diode lasers. This preliminary study
describes further miniaturization and cost reduction of the ONS system in the form of a compact, lightweight,
cordless, and inexpensive IR laser. A 140-mW, 1560-nm diode laser was integrated with a green aiming beam and
delivery optics into a compact ONS system. Surface and subsurface ONS was performed in a total of 5 rats, in vivo,
with measurement of an intracavernous pressure (ICP) response during CW laser irradiation for 30 s with a spot
diameter of 0.7 mm. Short-term, CW ONS of the prostate CN’s is feasible using a compact, inexpensive, batterypowered
IR laser diode system. This ONS system may represent an alternative to ENS for laboratory studies, and
with further development, a handheld option for ONS in the clinic to identify and preserve the CN’s during prostate
cancer surgery.
Laser Lithotripsy
Characterization of a 50-um-core optical fiber for potential use in Thulium fiber laser lithotripsy
Show abstract
Our laboratory is currently studying the Thulium fiber laser (TFL) as a potential alternative laser lithotripter to the
standard clinical Holmium:YAG laser. We have previously demonstrated efficient coupling of TFL energy into
fibers as small as 100-μm-core-diameter without damage to the proximal end. Although smaller fibers have greater
tendency to degrade at the distal tip during lithotripsy, fiber diameters (≤ 200 μm) have been shown to increase
saline irrigation rates through the working channel of a flexible ureteroscope, maximize ureteroscope deflection, and
reduce stone retropulsion during laser lithotripsy. In this study, a 50-μm-core-diameter, 85-μm-outer-diameter fiber
is characterized for TFL ablation of human calcium oxalate monohydrate urinary stones, ex vivo. The stone ablation
rate was measured to be 70 ± 22 μg/s for 35-mJ-pulse-energy, 500-μs-pulse-duration, and 50-Hz-pulse-rate. The ureteroscope working channel flow rate including the 50-μm fiber decreased by only 10% with no impairment of
ureteroscope deflection. The fiber delivered up to 15.4 ± 5.9 W under extreme bending (5-mm-radius) conditions.
Stone retropulsion and fiber burn-back averaged 201 ± 336 and 3000 ± 2600 μm, respectively, after 2 minutes. With further development, Thulium fiber laser lithotripsy using ultra-small, 50-μm-core fibers may introduce new integration and miniaturization possibilities and potentially provide an alternatiμe to conventional Holmium:YAG
laser lithotripsy using larger fibers.
Investigation on the impact of pulse duration for laser induced lithotripsy
Show abstract
Objective: In-vitro investigation of Ho:YAG-laser induced stone fragmentation was performed to identify potential impacts of different pulse durations on stone fragmentation characteristics. Materials and Methods: An innovative Ho:YAG laser system (Swiss LaserClast, EMS S.A., Nyon, Switzerland) with selectable long- or short pulse mode was tested with regard to its fragmentation properties. The pulse duration depends on the specific laser parameter used. Fragmentation tests (hand held, hands free, single pulse induced crater) on artificial BEGO-Stones and fiber burn back tests were performed under reproducible experimental conditions. Additionally, the repulsion of long versus short laser pulses was compared using the pendulum set-up. Results: Differences in fragmentation rates between the two pulse duration regimes were seen. The difference was, however, not statistically significant. Using long pulse mode, the fiber burn back is nearly negligible while in short pulse mode an increased burn back was seen. The results of the pendulum test showed that the deviation induced by the momentum of shorter pulses is increased compared to longer pulses. Conclusion: Long pulse-mode showed reduced side effects like repulsion and fiber burn back in comparison to short pulse-mode while fragmentation rates remained at a comparable level. Lower push back and reduced burn back of longer laser pulses may results in better clinical outcome of laser lithotripsy and more convenient handling during clinical use.
Rapid vaporization of kidney stones, ex vivo, using a Thulium fiber laser at pulse rates up to 500 Hz with a stone basket
Show abstract
The Holmium:YAG laser (λ = 2120 nm) is currently the preferred laser for fragmenting kidney stones in the clinic.
However, this laser has some limitations, including operation at low pulse rates and a multimode spatial beam
profile which prohibits its use with smaller, more flexible optical fibers. Our laboratory is studying the Thulium
fiber laser (λ = 1908 nm) as an alternative lithotripter. The TFL has several advantages, including lower stone
ablation thresholds, use with smaller and more flexible fibers, and operation at arbitrary pulse lengths and pulse
rates. Previous studies have reported increased stone ablation rates with TFL operation at higher pulse rates,
however, stone retropulsion remains an obstacle to even more efficient stone ablation. This study explores TFL
operation at high pulse rates in combination with a stone stabilization device (e.g. stone basket) for improved
efficiency. A TFL beam with pulse energy of 35 mJ, pulse duration of 500-μs, and pulse rates of 10-500 Hz was
coupled into 100-μm-core, low-OH, silica fibers, in contact mode with uric acid and calcium oxalate monohydrate
stones, ex vivo. TFL operation at 500 Hz produced UA and COM stone ablation rates up to 5.0 mg/s and 1.3 mg/s,
respectively. High TFL pulse rates produced increased stone ablation rates sufficient for use in the clinic.
Characterization of calculus migration during Ho:YAG laser lithotripsy by high speed camera using suspended pendulum method
Show abstract
Calculus migration is a common problem during ureteroscopic laser lithotripsy procedure to treat urolithiasis. A conventional experimental method to characterize calculus migration utilized a hosting container (e.g. a “V” grove or a test tube). These methods, however, demonstrated large variation and poor detectability, possibly attributing to friction between the calculus and the container on which the calculus was situated. In this study, calculus migration was investigated using a pendulum model suspended under water to eliminate the aforementioned friction. A high speed camera was used to study the movement of the calculus which covered zero order (displacement), 1st order (speed) and 2nd order (acceleration). A commercialized, pulsed Ho:YAG laser at 2.1 um, 365-um core fiber, and calculus phantom (Plaster of Paris, 10×10×10mm cube) were utilized to mimic laser lithotripsy procedure. The phantom was hung on a stainless steel bar and irradiated by the laser at 0.5, 1.0 and 1.5J energy per pulse at 10Hz for 1 second (i.e., 5, 10, and 15W). Movement of the phantom was recorded by a high-speed camera with a frame rate of 10,000 FPS. Maximum displacement was 1.25±0.10, 3.01±0.52, and 4.37±0.58 mm for 0.5, 1, and 1.5J energy per pulse, respectively. Using the same laser power, the conventional method showed <0.5 mm total displacement. When reducing the phantom size to 5×5×5mm (1/8 in volume), the displacement was very inconsistent. The results suggested that using the pendulum model to eliminate the friction improved sensitivity and repeatability of the experiment. Detailed investigation on calculus movement and other causes of experimental variation will be conducted as a future study.
An integrated fiber and stone basket device for use in Thulium fiber laser lithotripsy
Show abstract
The Thulium fiber laser (TFL) is being explored as an alternative laser lithotripter to the Holmium:YAG laser. The
TFL's superior near-single mode beam profile enables higher power transmission through smaller fibers with
reduced proximal fiber tip damage. Recent studies have also reported that attaching hollow steel tubing to the distal
fiber tip decreases fiber degradation and burn-back without compromising stone ablation rates. However,
significant stone retropulsion was observed, which increased with pulse rate. In this study, the hollow steel tip fiber
design was integrated with a stone basket to minimize stone retropulsion during ablation. A device was constructed
consisting of a 100-μm-core, 140-μm-OD silica fiber outfitted with 5-mm-long stainless steel tubing at the distal tip,
and integrated with a 1.3-Fr (0.433-mm-OD) disposable nitinol wire basket, to form an overall 1.9-Fr (0.633-mm-
OD) integrated device. This compact design may provide several potential advantages including increased
flexibility, higher saline irrigation rates through the ureteroscope working channel, and reduced fiber tip degradation
compared to separate fiber and stone basket manipulation. TFL pulse energy of 31.5 mJ with 500 μs pulse duration
and pulse rate of 500 Hz was delivered through the integrated fiber/basket device in contact with human uric acid
stones, ex vivo. TFL stone ablation rates measured 1.5 ± 0.2 mg/s, comparable to 1.7 ± 0.3 mg/s (P > 0.05) using standard bare fiber tips separately with a stone basket. With further development, this device may be useful for
minimizing stone retropulsion, thus enabling more efficient TFL lithotripsy at higher pulse rates.
Visualizing mechanical stress and liquid flow during laser lithotripsy
Show abstract
The mechanism of action of the holmium laser lithotripsy is attributed to explosive expanding and imploding
vapor bubbles in association with high-speed water jets creating high mechanical stress and cracking the stone
surface. A good understanding of this mechanism will contribute to the improvement and the safety of clinical
treatments. A new method has been developed to visualize the dynamics of mechanical effects and fluid flow
induced by Holmium laser pulses around the fiber tip and the stone surface. The fiber tip was positioned near the
surface of a stone on a slab of polyacrylamide gel submerged in water. The effects were captured with high
speed imaging at 2000-10000 f/s. The dynamics of the pressure wave after the pulse could be visualized by
observing the optical deformation of a fine line pattern in the background of the water container using digital
subtraction software. This imaging technique provides a good understanding of the mechanical effects
contributing to the effectiveness and safety of lithotripsy and can be used to study the optimal fiber shape and
position towards the stone surface.
Tissue Imaging II
Fluorescence spectroscopy using excitation and emission matrix for quantification of tissue native fluorophores and cancer diagnosis
Show abstract
Native fluorescence spectrum of normal and cancerous human prostate tissues is studied to distinguish between normal and cancerous tissues, and cancerous tissues at different cancer grade. The tissue samples were obtained from Cooperative Human Tissue Network (CHTN) and National Disease Research Interchange(NDRI). An excitation and emission matrix (EEM) was generated for each tissue sample by acquiring native fluorescence spectrum of the sample using multiple excitation wavelengths. The non-negative matrix factorization algorithm was used to generate fluorescence EEMs that correspond to the fluorophores in biological tissues, including tryptophan, collagen, elastin, nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD) and the background paraffin. We hypothesize that, as a consequence of metabolic changes associated with the development of cancer, the concentrations of NADH and FAD are different in normal and cancerous tissues, and also different for different cancer grades. We used the ratio of the abundances of FAD and NADH to distinguish between normal and cancerous tissues, and the tissue cancer grade. The FAD-to-NADH ratio was found to be the highest for normal tissue and decreased as the cancer grade increased.
Volumetric mosaicing for optical coherence tomography for large area bladder wall visualization
Show abstract
Optical coherence tomography (OCT) has shown potential as a complementary imaging modality to white light
cystoscopy (WLC) because it can visualize sub-surface details of the bladder wall, enabling it to stage early
cancers and visualize tumors undetectable to WLC. However, the inherently small field of view (FOV) of OCT
compared with the area of the bladder wall restricts its clinical utility. A large OCT FOV could improve surgical
planning by enabling complete visualization of tumor margins or could aid in early cancer detection by tracking
the appearance of the bladder wall over time. To overcome the limited FOV of OCT, we developed a method
to create mosaics of OCT volume data using a modified version of the N-dimensional scale invariant feature
transform (N-SIFT) algorithm: white-light-enhanced N-SIFT (WhiLE-NS). WhiLE-NS adds a pre-processing
step to N-SIFT that uses white light images co-registered with OCT volumes to select small, highly overlapped
volumes on which to run N-SIFT. This pre-processing step adds minimal computational time and enables a 200-
fold decrease in the amount of time required to register two volumes compared with N-SIFT alone. Quantitatively,
WhiLE-NS achieves nearly sub-pixel registration accuracy, and qualitatively, we demonstrate that the algorithm
can generate large FOV mosaics of ex vivo bladder tissue. The realization of this algorithm is a critical step to
enabling OCT to contribute meaningfully to bladder surveillance and surgical guidance.
Advanced Imaging and Novel Treatment Strategies in Otology
Effect of LLLT on the level of ATP and ROS from organ of corti cells
Show abstract
It is well established that ototoxic antibiotics and acoustic trauma can damage cochlear hair cells and cause
hearing loss. Previous studies using transcanal LLLT (Low level laser therapy) showed that LLLT can promote
recovery of hearing thresholds and cochlear hair cells. However, its mechanism has not been studied. Aim:
The aim of this study is to investigate the mechanism of hearing recovery from gentamicin induced ototoxic
hearing loss by LLLT. Methods: HEI- OC1 (House ear institute organ of Corti) cells were cultured for 18
hours and ototoxicity was induced by gentamicin (GM) treatment to the cells. Cultured cells were divided into
6 groups, No treatment control, LLLT only, GM 6.6 mM and GM 13.1 mM, GM 6.6 mM+LLLT and GM 13.1
mM+LLLT cells. LD laser 808 nm, 15 mW, was irradiated to the cultured cells for 15 min, at 4 hours after GM
treatment to the cells. ATP was assayed using the ATP assay Kit. ROS was measured using confocal
microscope after application of H2DCFDA dye. Results: ATP was decreased in GM 13.1 mM cells and
increased in LLLT only cells and GM 13.1 mM+LLLT cells compared to control and 13.1 mM cells. ROS was
increased in GM 6.6 mM and GM 13.1 mM cells, and decreased in GM 6.6 mM+LLLT and GM 13.1
mM+LLLT cells compared to GM 6.6 and 13.1 mM cells immediately after laser irradiation. Conclusion: This
study demonstrated that LLLT on GM treated HEI-OC1 cells increased ATP and decreased ROS that may
contribute to the recovery of hearing.
3D optical coherence tomography image registration for guiding cochlear implant insertion
Show abstract
In cochlear implant surgery, an electrode array is inserted into the cochlear canal to restore hearing to a person who is
profoundly deaf or significantly hearing impaired. One critical part of the procedure is the insertion of the electrode
array, which looks like a thin wire, into the cochlear canal. Although X-ray or computed tomography (CT) could be used
as a reference to evaluate the pathway of the whole electrode array, there is no way to depict the intra-cochlear canal and
basal turn intra-operatively to help guide insertion of the electrode array. Optical coherent tomography (OCT) is a highly
effective way of visualizing internal structures of cochlea. Swept source OCT (SSOCT) having center wavelength of 1.3
micron and 2D Galvonometer mirrors was used to achieve 7-mm depth 3-D imaging. Graphics processing unit (GPU),
OpenGL, C++ and C# were integrated for real-time volumetric rendering simultaneously. The 3D volume images taken
by the OCT system were assembled and registered which could be used to guide a cochlear implant. We performed a
feasibility study using both dry and wet temporal bones and the result is presented.
OCT for Functional Laryngeal Imaging
Automated working distance adjustment for a handheld OCT-Laryngoscope
Show abstract
Optical coherence tomography (OCT) is an imaging technique which enables diagnosis of vocal cord tissue structure by
non-contact optical biopsies rather than invasive tissue biopsies. For diagnosis on awake patients OCT was adapted to a
rigid indirect laryngoscope. The working distance must match the probe-sample distance, which varies from patient to
patient. Therefore the endoscopic OCT sample arm has a variable working distance of 40 mm to 80 mm. The current
axial position is identified by automated working distance adjustments based on image processing. The OCT reference
plane and the focal plane of the sample arm are moved according to position errors. Repeated position adjustment during
the whole diagnostic procedure keeps the tissue sample at the optimal axial position. The auto focus identifies and
adjusts the working distance within the range of 50 mm within a maximum time of 2.7 s. Continuous image stabilisation
reduces axial sample movement within the sampling depth for handheld OCT scanning. Rapid autofocus reduces the
duration of the diagnostic procedure and axial position stabilisation eases the use of the OCT laryngoscope. Therefore
this work is an important step towards the integration of OCT into indirect laryngoscopes.
Basic Research and Engineering Concepts for Avanced Head and Neck Imaging
Self optical motion-tracking for endoscopic optical coherence tomography probe using micro-beamsplitter probe
Show abstract
Long range optical coherence tomography (OCT), with its high speed, high resolution, non-ionized properties and cross-sectional imaging capability, is suitable for upper airway lumen imaging. To render 2D OCT datasets to true 3D anatomy, additional tools are usually applied, such as X-ray guidance or a magnetic sensor. X-ray increases ionizing radiation. A magnetic sensor either increases probe size or requires an additional pull-back of the tracking sensor through the body cavity. In order to overcome these limitations, we present a novel tracking method using a 1.5 mm×1.5mm, 90/10-ratio micro-beamsplitter: 10% light through the beam-splitter is used for motion tracking and 90% light is used for regular OCT imaging and motion tracking. Two signals corresponding to these two split-beams that pass through different optical path length delays are obtained by the detector simultaneously. Using the two split beams’ returned signals from the same marker line, the 2D inclination angle of each step is computed. By calculating the 2D inclination angle of each step and then connecting the translational displacements of each step, we can obtain the 2D motion trajectory of the probe. With two marker lines on the probe sheath, 3D inclination angles can be determined and then used for 3D trajectory reconstruction. We tested the accuracy of trajectory reconstruction using the probe and demonstrated the feasibility of the design for structure reconstruction of a biological sample using a porcine trachea specimen. This optical-tracking probe has the potential to be made as small as an outer diameter of 1.0mm, which is ideal for upper airway imaging.
Characterizing fluorescent imaging properties of antibodies conjugated to IRDye800CW for use in imaging of head and neck cancer
Robert C. Foster,
Asher M. Krell,
Thomas K. Chung,
et al.
Show abstract
Introduction: Proteins conjugated to the near infrared (NIR) moieties for detection of head and neck cancers are being
translated to the clinic. However, little is known about the fluorescent properties of IRDye800CW after conjugation to
antibodies. We investigated factors that may alter the real-time observed fluorescence of antibody conjugated dye and
the rate of fluorescent signal loss. Methods: Signal loss was examined using three FDA approved monoclonal antibodies conjugated to IRDye800CW (LICOR) over a period of 15 days. Temperature effects on fluorescence were examined for conjugated dye in both solution and a mouse tumor model. Samples were cooled to -20°C then warmed to predetermined temperatures up to 60°C with imaging performed using the PEARL Impulse (LI-COR) and LUNA (Novadaq) systems.
Results: Short term fluorescent signal loss (< 1 hour) was linear, while long term loss (15 days) was exponential with
significant increases in rate observed with light exposure and increased temperatures. Cooling of tumor tissue at -20°C
was shown to significantly increase tumor fluorescence on both imaging modalities when compared to room temperature
(p=0.008, p=0.019). Concurrently the ratio of tumor to background fluorescent signal (TBR) increased with decreasing
temperature with statistically significant increases seen at -20°C and 4°C (p=0.0015, p=0.03).
Conclusions: TBR is increased with decreasing sample temperature, suggesting that the clinical exam of fluorescently
labeled tissues may be improved at cooler temperatures. Our results indicate that both the rate of signal loss and the
change in fluorescence with temperature observed for IRDye800CW are independent of the conjugating antibody.
Practical Results of Novel Imaging Technology in Head and Neck Lesions
Optical biopsy on head and neck tissue using full-field OCT: a pilot study
Show abstract
Here we evaluate the clinical value of Full-Field OCT imaging in the management of patients with Head and Neck
cancers by making a reliable histological diagnosis on FFOCT images produced during preoperative procedure. FFOCT
performs a true "virtual extemporaneous exam" that we want to compare to the gold standard (extemporaneous and
conventional histology with H and E staining). This new optical technology could be useful when diagnosing a lesion,
cancerous or precancerous, or at the time of its surgical management.
Full-Field Optical Coherence Tomography virtually slices the tissue using white light interferometry to produce in-depth
2D images with an isotropic resolution around 1 micrometer. With such a high resolution FFOCT systems produce
”optical biopsy” images that are similar to that obtained with classical histology procedures, but without any staining and
in only a few minutes.
We imaged freshly excised samples from patients, of mouth, tongue, epiglottis and larynx tissues, both healthy and
cancerous. FFOCT images were acquired and later compared with histology of the same samples. Common features
were identified and characteristics of each tissue type were matched in order to form an image atlas for pathologist
training. We were able to identify indicators of tumors such as heterogeneities in cell distribution, surrounding stroma,
anomalous keratinization…
In conclusion, FFOCT is a fast, non-invasive, non-destructive imaging tool that can be inserted into the pathology lab
workflow and can provide a quick assessment of microscopic tissue architecture and content. Furthermore we are
developing a similar system with a rigid endoscopic probe in order to do in vivo and in situ high-resolution imaging. Our
probe could thus guide the surgeon in real time before and during excision and ensure a more precise gesture.
Widefield fluorescence imaging as an auxiliary tool to select the biopsy site for actinic cheilitis diagnosis
C. Kurachi D.D.S.,
A. Cosci,
A. Takahama Jr.,
et al.
Show abstract
Actinic cheilitis (AC) is considered a potentially malignant disorder that mainly affects the
lower lip, and it is caused by prolonged sun exposure. Clinical diagnosis relies on visual
inspection by a trained clinician, when suspected of dysplasia changes, a biopsy is required.
The heteregenous characteristics of the AC, makes the choice of the biopsy site a difficult task.
Fluorescence detection has been presented as a useful tool to to detect biochemical and
morphological tissue features related to cancer diagnosis, but still its effectiveness to
discriminate premalignant lesion is not completely defined. In this clinical study, 57 AC patients
were investigated using widefield fluorescence imaging (WFI) to evaluate the efficacy of this
technique as an auxiliary tool to biopsy site location. A handheld fluorescence system based on
400-450 nm LED illumination Distinct trained clinicians evaluate the patient either with the
conventional examination or the WFI, and were blinded to the other evaluation. A biopsy site
was chosen based on the clinical examination, and another site was chosen using the
fluorescence visualization. A total of 114 punch biopsies were performed, and 93% of the
tissue samples presented epithelial dysplasia. The majority of the sites that presented
moderate or severe dysplasia were sites chosen by WFI, showing its efficiency to improve the
diagnosis of AC.
PDT and Related Technology for Malignant and Pre-Malignant Head and Neck Lesions
Determination of tissue optical properties in PDT treated head and neck patients
Show abstract
Determination of optical properties (absorption (μa) and scattering (μs’) coefficients) in human tissue is important when
it comes to accurate calculation of fluence rate in and around tissue area. ALA application to the tissue induces
production of protoporphyrin IX when activated by red light. Changes in the tissue optical properties can send
information such as treatment outcome and tissue drug concentration.
Patients in this study were treated with PDT for head and neck mucosal dysplasia. They were enrolled in a phase I study
of escalating light doses and oral ALA with 60mg/kg. Red light at 630nm was administered to the tumor from a laser.
The light dose was escalated from 50-200J/cm2 with a measured fluence rate at tissue surface of 100mW/cm2.
We developed a light detection device for the purpose of determining optical properties in vivo using the semi-infinite
method. The light detection device consists of two parallel, placed 5mm apart. In one of the catheters a 2 mm long linear
diffusing light source is placed while in the second catheter, a calibrated isotropic detector is placed. The detector is
scanned along the length of the light source containing catheter. Scans are done with the device placed on the treatment
area (tumor) and on the normal tissue. Optical properties were measured in-vivo before and after PDT delivery for both
normal tissue and tumor.
Plasmonic nanobubble theranostics for intra-operative and preventive treatment of head and neck squamous cell carcinoma
Ekaterina Y. Lukianova-Hleb,
Xiaoyang Ren,
Rupa R. Sawant,
et al.
Show abstract
Chemoradiation-resistant cancer cells and unresectable micro-tumors limit treatment efficacy and lead to high nonspecific
toxicity or recurrence in head and neck cancers. We show the cancer cell-specific, on-demand enhancement of
the chemo- and chemoradiation therapy with mechanical intracellular impact of plasmonic nanobubbles, a laser pulseinduced
explosive nano-event, not a particle. We report cellular mechanisms of cancer cell-specific detection and
enhancement of the entry drug and X-ray dose and validate these mechanisms in vitro and in vivo for head and neck
squamous cell carcinoma. Plasmonic nanobubble technology showed more than 10-fold enhancement of the therapeutic
efficacy compared to standard chemoradiation in murine models of primary, microscopic residual and recurrent diseases.
At the same time our technology efficiently spared adjacent normal tissues due to the reduction of the effective
therapeutic doses of drug by 30-40 fold, X-rays by 15-fold and the treatment time to a single procedure. The developed
plasmonic nanobubble technology transforms a standard macro-therapy into a cell-level on-demand theranostic
treatment for primary, adjuvant and adjunct applications.
Current Concepts in Laser Surgery and Optical Tracking
Investigation on laser induced salivary stone fragmentation
Show abstract
Objective: It was the objective of this in-vitro study to investigate photon-based techniques for identifying the
composition and fragmentation of salivary stones using a Ho:YAG laser.
Materials and Method: Salivary stones (n=47) extracted from patients with clinical symptoms of sialolithiasis were
examined in-vitro. After extraction, the stones were kept in Ringers solution until size and volume measurements could
be performed. Thereafter, dual-energy CT scans (DECT) were performed to classify the composition of the stones.
Subsequently, fluorescence measurements were performed by taking images under blue light excitation as well as by
fluorescence spectroscopy, measuring excitation-emission-matrixes (EEM). Further investigation to identify the exact
composition of the stone was performed by Raman spectroscopy and FTIR spectroscopy of stone fragments and debris.
Fragmentation was performed in an aquarium set-up equipped with a mesh (hole: 1.5mm) using a Ho:YAG-laser to
deliver laser pulses of 0.5, 1.0 and 1.5J/pulse at a frequency of 3Hz through a 200μm-fibre to the stone surface. The
collected data were analyzed and fragmentation rates were calculated. Finally, correlation between stone composition
and fragmentation was performed.
Results: Blue light fluorescence excitation resulted in either fluorescence in the green spectral region or in a
combination of green and red fluorescence emission. EEM-measurement showed the corresponding spectra. Raman
spectroscopy showed a mixture of carbonate apatite and keratin. DECT results in evidence of calcium containing
components. FTIR-spectroscopy results showed that carbonate apatite is the main component. Fragmentation experiment
showed a dependency on the energy per pulse applied if the evaluation implies the ratio of fragmented weight to pulse,
while the ratio fragmented weight to energy remains about constant for the three laser parameter used.
Conclusion: The composition of salivary stones could be determined using different photonic techniques. Attempts to
correlate salivary stone composition to fragmentation rates resulted in no correlation. Thus it could be concluded that
each salivary stone could be easily destroyed using Ho:YAG-laser light by means of a 200μm bare fibre at lowest energy
per pulse.
Accuracy of optical navigation systems for automatic head surgery: optical tracking versus optical coherence tomography
Jesús Díaz Díaz,
Mauro H. Riva,
Omid Majdani M.D.,
et al.
Show abstract
The choice of a navigation system highly depends on the medical intervention and its accuracy demands. The most commonly used systems for image guided surgery (IGS) are based on optical and magnetic tracking systems. This paper compares two optical systems in terms of accuracy: state of the art triangulation-based optical tracking (OT) and optical coherence tomography (OCT). We use an experimental setup with a combined OCT and cutting laser, and an external OT. We simulate a robotic assisted surgical intervention, including planning, navigation, and processing, and compare the accuracies reached at a specific target with each navigation system.
Efficient tissue ablation using a laser tunable in the water absorption band at 3 microns with little collateral damage
Alexandra Nierlich,
Danail Chuchumishev,
Elizabeth Nagel,
et al.
Show abstract
Lasers can significantly advance medical diagnostics and treatment. At high power, they are typically used as cutting
tools during surgery. For lasers that are used as knifes, radiation wavelengths in the far ultraviolet and in the near
infrared spectral regions are favored because tissue has high contents of collagen and water. Collagen has an absorption
peak around 190 nm, while water is in the near infrared around 3,000 nm. Changing the wavelength across the
absorption peak will result in significant differences in laser tissue interactions. Tunable lasers in the infrared that could
optimize the laser tissue interaction for ablation and/or coagulation are not available until now besides the Free Electron
Laser (FEL). Here we demonstrate efficient tissue ablation using a table-top mid-IR laser tunable between 3,000 to
3,500 nm. A detailed study of the ablation has been conducted in different tissues. Little collateral thermal damage has
been found at a distance above 10-20 microns from the ablated surface. Furthermore, little mechanical damage could be
seen in conventional histology and by examination of birefringent activity of the samples using a pair of cross polarizing
filters.
Upper Airway OCT and Spectroscopy
Analysis and digital 3D modeling of long-range fourier-domain optical coherence tomography images of the pediatric subglottis
Show abstract
In neonatal and pediatric patients who require long-term endotracheal intubation, the subglottic mucosa is most
susceptible to injury from the endotracheal tube. At present, there is no diagnostic modality to identify early signs of
subglottic mucosal pathology. Fourier-domain optical coherence tomography (FD-OCT) is a minimally-invasive
imaging modality which acquires high-resolution, 3D cross-sectional images of biological tissue. FD-OCT of the
neonatal and pediatric airways was conducted to evaluate subglottic microanatomy and histopathologic changes
associated with prolonged intubation.
FD-OCT of the larynx, subglottis and proximal trachea was conducted in pediatric and neonatal patients. OCT image
sets were analyzed by anatomic categorization (airway level), tissue segmentation and mucosa micrometry in MATLAB.
Subsequently, OCT data sets were rendered into digital 3D airway models in Mimics software. We report original
methods for subglottic OCT image processing and analysis.
Constructing 3D models of the pediatric upper airway from long range optical coherence tomography images
Tony D. Nguyen,
Erica Su,
Frances Lazarow,
et al.
Show abstract
Long-range optical coherence tomography has been developed to image the upper airway, obtaining high resolution, cross-sectional images of the hollow structure. The information obtained from the anatomical structure of the airway is important to objectively identify regions of airway obstruction. This paper describes a technique to create 3D reconstructions of the upper airway from LR-OCT images. Herein we outline the necessary steps to generate these 3D models, including image processing techniques, manual tissue segmentation in Mimics, anatomical curvature bending, and the final STL model rendition. These 3D models were used to qualitatively analyze structural changes before and after surgical interventions. The reconstructions could also be used for further computational fluid dynamics analysis.
Raman spectroscopy and oral exfoliative cytology
Show abstract
Early detection of oral cancers can substantially improve disease-free survival rates. Ex vivo and in vivo Raman
spectroscopic (RS) studies on oral cancer have demonstrated the applicability of RS in identifying not only malignant and
premalignant conditions but also cancer-field-effects: the earliest events in oral carcinogenesis. RS has also been explored
for cervical exfoliated cells analysis. Exfoliated cells are associated with several advantages like non-invasive sampling,
higher patient compliance, transportation and analysis at a central facility: obviating need for on-site instrumentation. Thus,
oral exfoliative cytology coupled with RS may serve as a useful adjunct for oral cancer screening. In this study, exfoliated
cells from healthy controls with and without tobacco habits, premalignant lesions (leukoplakia and tobacco-pouch-keratosis)
and their contralateral mucosa were collected using a Cytobrush. Cells were harvested by vortexing and centrifugation at
6000 rpm. The cellular yield was ascertained using Neubauer’s chamber. Cell pellets were placed on a CaF2 window and Raman spectra were acquired using a Raman microprobe (40X objective) coupled HE-785 Raman spectrometer.
Approximately 7 spectra were recorded from each pellet, following which pellet was smeared onto a glass slide, fixed in
95% ethanol and subjected to Pap staining for cytological diagnosis (gold standard). Preliminary PC-LDA followed by
leave-one-out cross validation indicate delineation of cells from healthy and all pathological conditions. A tendency of
classification was also seen between cells from contralateral, healthy tobacco and site of premalignant lesions. These results
will be validated by cytological findings, which will serve as the basis for building standard models of each condition.
Raman spectroscopy of oral tissues: correlation of spectral and biochemical markers
Show abstract
Introduction
Optical spectroscopic methods are being explored as novel tools for early and non-invasive cancer diagnosis. Both ex
vivo and in vivo Raman spectroscopic studies carried out in oral cancer over the past decade have demonstrated that
spectra of normal tissues are rich in lipids while tumor spectra show predominance of proteins. An accurate
understanding of spectral features with respect to the biochemical composition is a pre-requisite before transferring these
technologies for routine clinical usage. Therefore, in the present study, we have carried out Raman and biochemical
studies on same tissues to correlate spectral markers and biochemical composition of normal and tumor oral tissues.
Materials and Methods
Spectra of 20 pairs of normal and tumor oral tissues were acquired using fiber-optic probe coupled HE-785 Raman
spectrometer. Intensity associated with lipid (1440 cm-1) and protein (1450 and 1660 cm-1) bands were computed using
curve-deconvolution method. Same tissues were then subjected to biochemical estimations of major biomolecules i.e.,
protein, lipid and phospholipids.
Results and Discussion
The intensity of the lipid band was found to be higher in normal tissues with respect to tumors, and the protein band was
higher in tumors compared to normal tissues. Biochemical estimation yielded similar results i.e. high protein to lipid or
phospholipid ratio in tumors with-respect to normal tissues. These differences were found to be statistically significant.
Conclusion
Findings of curve-deconvolution and biochemical estimation correlate very well and corroborate the spectral profile
noted in earlier studies.
Spectroscopy
Performance improvement by a broadband super-luminescent diode light source in 1.7-µm spectroscopic spectral-domain optical coherence tomography for lipid distribution imaging in a coronary artery
Show abstract
We develop a 1.7-μm optical coherence tomography (OCT) system using a broadband light source based on superluminescent diodes (SLDs) and investigated the possibility of plaque detection by a spectroscopic OCT (S-OCT)
method. The SLD-based light source realizes an output power about 20mW and a 3-dB bandwidth over 120nm for
optimization of driving current in each SLD. Regarding performance of the 1.7-μm spectral-domain OCT system with
the light source, the system sensitivity is 104dB in maximum at the A-scan rate of 47kHz, which is fifty times as high as
that in the previous study with a super-continuum light source. Moreover, we perform visualization of lipid distribution
at the A-scan frame of 47kHz by an in-vitro artery model which is made of a piece of porcine coronary artery and a lardfilled
nylon tube as a plaque phantom. We confirm that the sensitivity and specificity between artery and plaque area in
optimal condition for lipid detection at a specific frame image is over 90% and there are high lipid scores at the inside of
plaque phantom in other frame images at the same condition. It indicates the possibility of plaque detection in
intravascular OCT.
Quantitative evaluation of atherosclerotic plaque phantom by near-infrared multispectral imaging with three wavelengths
Show abstract
Atherosclerosis is a primary cause of critical ischemic disease. The risk of critical event is involved the content of lipid
in unstable plaque. Near-infrared (NIR) range is effective for diagnosis of atherosclerotic plaque because of the
absorption peaks of lipid. NIR multispectral imaging (NIR-MSI) is suitable for the evaluation of plaque because it can
provide spectroscopic information and spatial image quickly with a simple measurement system. The purpose of this
study is to evaluate the lipid concentrations in plaque phantoms quantitatively with a NIR-MSI system. A NIR-MSI
system was constructed with a supercontinuum light, a grating spectrometer and a MCT camera. Plaque phantoms with
different concentrations of lipid were prepared by mixing bovine fat and a biological soft tissue model to mimic the
different stages of unstable plaque. We evaluated the phantoms by the NIR-MSI system with three wavelengths in the
band at 1200 nm. Multispectral images were processed by spectral angle mapper method. As a result, the lipid areas of
phantoms were effectively highlighted by using three wavelengths. In addition, the concentrations of lipid areas were
classified according to the similarity between measured spectra and a reference spectrum. These results suggested the
possibility of image enhancement and quantitative evaluation of lipid in unstable plaque with a NIR-MSI.
Myocardium and Therapy
Calcium and voltage imaging in arrhythmia models by high-speed microscopy
Show abstract
Alterations in intracellular cardiomyocyte calcium handling have a key role in initiating and sustaining arrhythmias.
Arrhythmogenic calcium leak from sarcoplasmic reticulum (SR) can be attributed to all means by which calcium exits
the SR store in an abnormal fashion. Abnormal SR calcium exit maymanifest as intracellular Ca2+ sparks and/or Ca2+
waves. Ca2+ signaling in arrhythmogenesis has been mainly studied in isolated cardiomyocytes and given that the
extracellular matrix influences both Ca2+ and membrane potential dynamics in the intact heart and underlies
environmentally mediated changes, understanding how Ca2+ and voltage are regulated in the intact heart will represent a
tremendous advancement in the understanding of arrhythmogenic mechanisms. Using novel high-speed multiphoton
microscopy techinques, such as multispot and random access, we investigated animal models with inherited and acquired
arrhythmias to assess the role of Ca2+ and voltage signals as arrhythmia triggers in cell and subcellular components of
the intact heart and correlate these with electrophysiology.
Prediction of myocardial damage depth induced by extracellular photosensitization reaction using fluorescence measurement in vivo
Show abstract
We experimentally studied the correlation between myocardial damage depth due to the extracellular photosensitization
reaction (PR) using talaporfin sodium and fluorescence-fall amount (FA), which is calculated from the measured
backscattering fluorescence intensity via a manipulatable 7 Fr. laser catheter during the PR operation in vivo to establish
treatment depth predictor for a non-thermal tachyarrhythmia treatment. The PR was performed to left and/or right
ventricle in the open-chest canine heart. The laser irradiation of 663±2 nm in wavelength via the laser catheter was
operated 15 min after the intravenous administration of talaporfin sodium with concentration of 36.2±8.0 μg/ml in plasma. The irradiation was operated with irradiance of 5, 10, 20 W/cm2, and duration of 5, 10, 20 s. Backscattering
fluorescence of 710±2 nm in wavelength was measured via the laser catheter during the PR. The FA was calculated
multiplying the irradiation duration by the fluorescence-fall, which is subtraction of the fluorescence intensity at the
kickoff and end of the irradiation. The canine heart was extracted 1 week after the PR and HE stained specimen was
histologically evaluated. The correlation of the myocardial damage depth and FA was investigated. We found that FA
obtained a logarithmic relation to the myocardial damage depth. We think that the FA might be available to predict the
PR induced myocardial damage depth for the application of tachyarrhythmia treatment under catheterization in vivo.
Is it possible to prevent morbidity on post cardiovascular surgery applying low level laser therapy?
Show abstract
Background and Objective: Complications following cardiovascular surgery incision
are common in mediastinitis and wound dehiscence form, a 47% mortality rate
remaining. Low Level Laser Therapy (LLLT) has been employed mainly to its
effectiveness analgesic and anti-inflammatory actions, aiding the tissue repair process.
The aim of this study was to evaluate infrared LLLT onto surgical incision in patients
submitted to cardiovascular surgery. Materials and Methods: 40 patients were divided
in two groups: Placebo Group (G1) – conventional therapy + “Laser pointer” and Laser
Group (G2) - conventional therapy + Infrared Laser irradiation on surgical incision.
Diode Laser was employed, C.W. mode, around the surgical wound bed, on immediate
Post Operative (PO), 1st PO and 3rd PO with the following parameters: wavelength (λ):
830nm, P=35mW, E=0,75J. Results: G2 didn’t present any complication and 5% of
patients in G1 developed incision dehiscence and infection. On 7thPO, still a large
amount of G1 patients showed pain and unquestionable inflammatory signs surrounding
the surgical wound, when compared to G2. Besides, hospital stay in Laser Group was 2
times shorter than in Placebo Group (p-value=0.001). Conclusion: Infrared Laser
denoted to be safe and exceptionally valuable tools in preventing morbidities on post
cardiovascular surgeries.
Light and Sound
Diagnostic accuracy of integrated intravascular ultrasound and optical coherence tomography (IVUS-OCT) system for coronary plaque characterization
Show abstract
Intravascular ultrasound (IVUS) imaging and optical coherence tomography (OCT), two commonly used intracoronary imaging modalities, play important roles in plaque evaluation. The combined use of IVUS (to visualize the entire plaque volume) and OCT (to quantify the thickness of the plaque cap, if any) is hypothesized to increase plaque diagnostic accuracy. Our group has developed a fully-integrated dual-modality IVUS-OCT imaging system and 3.6F catheter for simultaneous IVUS-OCT imaging with a high resolution and deep penetration depth. However, the diagnostic accuracy of an integrated IVUS-OCT system has not been investigated. In this study, we imaged 175 coronary artery sites (241 regions of interest) from 20 cadavers using our previous reported integrated IVUS-OCT system. IVUS-OCT images were read by two skilled interventional cardiologists. Each region of interest was classified as either calcification, lipid pool or fibrosis. Comparing the diagnosis by cardiologists using IVUSOCT images with the diagnosis by the pathologist, we calculated the sensitivity and specificity for characterization of calcification, lipid pool or fibrosis with this integrated system. In vitro imaging of cadaver coronary specimens demonstrated the complementary nature of these two modalities for plaques classification. A higher accuracy was shown than using a single modality alone.
Bi-modal imaging of atherosclerotic plaques: Automated method for co-registration between fluorescence lifetime imaging and intravascular ultrasound data
Show abstract
The risk of atherosclerosis plaque rupture cannot be assessed by the current imaging systems and thus new multi-modal
technologies are under investigation. This includes combining a new fluorescence lifetime imaging (FLIm) technique,
which is sensitive to plaque biochemical features, with conventional intravascular ultrasound (IVUS), which provides
information on plaque morphology. In this study we present an automated method allowing for the co-registration of
imaging data acquired based on these two techniques. Intraluminal studies were conducted in ex-vivo segments of human
coronaries with a multimodal catheter integrating a commercial IVUS (40 MHz) and a rotational side-viewing fiber
based multispectral FLIm system (355 nm excitation, 390±20, 452±22 and 542±25 nm acquisition wavelengths). The proposed method relies on the lumen/intima boundary extraction from the IVUS polar images. Image restoration is applied for the noise reduction and edge enhancement, while gray-scale peak tracing over the A-lines of the IVUS polar images is applied for the lumen boundary extraction. The detection of the guide-wire artifact is used for the angular
registration between FLIm and IVUS data, after which the lifetime values can be mapped onto the segmented
lumen/intima interface. The segmentation accuracy has been assessed against manual tracings, providing 0.120±0.054
mm mean Hausdorff distance. This method makes the bi-modal FLIm and IVUS approach feasible for comprehensive
intravascular diagnostic by providing co-registered biochemical and morphological information about atherosclerotic
plaques.
Poster Session
Comparison of frequency domain optical coherence tomography and quantitative coronary angiography for the assessment of coronary lesions
Show abstract
Quantitative coronary angiography (QCA) has been used as a standard technique for the evaluation of coronary artery
disease for many years. Intracoronary optical coherence tomography (OCT) offers higher resolution, faster image
acquisition speeds and greater sensitivity than the intravascular ultrasound (IVUS). Recently developed frequency
domain OCT (FD-OCT) systems overcome many technical limitations of conventional time domain OCT systems (TDOCT).
The main objective of this study was to compare the FD-OCT and QCA measurements for the assessment of
coronary lesions. A total of 21 stenoses in 18 patients were analysed using QCA and FD-OCT. The average minimum
lumen diameter (MLD) and percent lumen area stenosis (%AS) by QCA were 1.52±0.44 mm and 68±9% respectively.
The average MLD and %AS by FD-OCT were 1.32±0.38 mm and 63±14% respectively. There was a moderate but
significant correlation between QCA and FD-OCT measured MLD (r = 0.5, p < 0.01) and %AS (r = 0.56, p < 0.01).
Bland-Altman analysis showed that the mean differences between the QCA and FD-OCT measurements were 0.18±0.81
(limits of agreement: -0.63 to 0.99) for MLD and 4.4±22.8 (limits of agreement: -18.4 to 27.2) for %AS. The root mean
square error (RMSE) between the QCA and FD-OCT measured MLD and %AS was ±0.44 mm and ±12.1%
respectively.
Cardiac tissue characterization using near-infrared spectroscopy
Show abstract
Cardiac tissue from swine and canine hearts were assessed using diffuse reflectance near-infrared spectroscopy (NIRS) ex vivo. Slope measured between 800-880 nm reflectance was found to reveal differences between epicardial fat and normal myocardium tissue. This parameter was observed to increase monotonically from measurements obtained from the onset of radiofrequency ablation (RFA). A sheathe-style fiber optic catheter was then developed to allow real-time sampling of the zone of resistive heating during RFA treatment. A model was developed and used to extract changes in tissue absorption and reduced scattering based on the steady-state diffusion approximation. It was found that key changes in tissue optical properties occur during application of RF energy and can be monitored using NIRS. These results encourage the development of NIRS integrated catheters for real-time guidance of the cardiac ablation treatment.
Bone Surgery and Ablation
Efficient bone cutting with the novel diode pumped Er:YAG laser system: in vitro investigation and optimization of the treatment
parameters
Karl Stock,
Rolf Diebolder,
Florian Hausladen,
et al.
Show abstract
It is well known that flashlamp pumped Er:YAG lasers allow efficient bone ablation due to strong absorption at 3μm by
water. Preliminary experiments revealed also a newly developed diode pumped Er:YAG laser system (Pantec
Engineering AG) to be an efficient tool for use for bone surgery.
The aim of the present in vitro study is the investigation of a new power increased version of the laser system with higher
pulse energy and optimization of the treatment set-up to get high cutting quality, efficiency, and ablation depth.
Optical simulations were performed to achieve various focus diameters and homogeneous beam profile. An appropriate
experimental set-up with two different focusing units, a computer controlled linear stage with sample holder, and a
shutter unit was realized. By this we are able to move the sample (slices of pig bone) with a defined velocity during the
irradiation. Cutting was performed under appropriate water spray by moving the sample back and forth. After each path
the ablation depth was measured and the focal plane was tracked to the actual bottom of the groove. Finally, the cuts
were analyzed by light microcopy regarding the ablation quality and geometry, and thermal effects.
In summary, the results show that with carefully adapted irradiation parameters narrow and deep cuts (ablation depth >
6mm, aspect ratio approx. 20) are possible without carbonization.
In conclusion, these in vitro investigations demonstrate that high efficient bone cutting is possible with the diode pumped
Er:YAG laser system using appropriate treatment set-up and parameters.
Laser technologies in treatment of degenerative-dystrophic bone diseases in children
Show abstract
Two low invasive laser technologies for treatment of degenerative-dystrophic bone diseases in children are presented.
The first is the transcutaneous laser osteoperforation developed by us and initially applied for treatment of different
inflammatory and traumatic diseases (osteomyelitides, osteal and osteoarticular panaritiums, delayed unions, false joints,
and others). Now the technology was applied to treatment of aseptic osteonecrosis of different localizations in 134
children aged from 1 to 16 years, including 56 cases with necrosis of femoral head (Legg-Calve-Perthes disease), 42 with
necrosis of 2nd metatarsal bone head (Kohler II disease), and 36 with necrosis of tibial tuberosity (Osgood–Schlatter
disease). The second technology is the laser intracystic thermotherapy for treatment of bone cysts. The method was
applied to 108 children aged from 3 to 16 years with aneurismal and solitary cysts of different localizations. In both
technologies a 970 nm diode laser was used. The suggested technologies increase the efficiency of treatment, reduce its
duration, can be performed on outpatient basis, which resulted in great economical effect.
Bone graft complications: what can we do to prevent them?
Show abstract
Introduction:
Bone grafts are commonly used in oral and maxillofacial surgery, helping to restore missing bone structure and provide
osseous support. In spite of their reported success, complications can and do arise. Examples include loosening and
resorption of the graft, infection, and complete loss of the graft. These complications can potentially lead to larger
defects, necessitating additional procedures to correct the problem. This not only causes great discomfort to the patient,
but also drains considerable time and resources away from the clinician. Thus, improvements on identifying ways to
identify and prevent these complications are constantly being sought. We have performed a literature review and
identified several areas in the field of optics that could potentially help solve our problem.
Optical Techniques:
Raman spectroscopy has been shown to provide a transcutaneous measurement of bone mineral and matrix Raman
bands. This could potentially provide surgeons with the ability to more accurately assess bone graft osseointegration.
In-vivo near-infrared optical imaging could potentially provide accurate diagnosis of pathologic lesions such as
osteosarcoma. Contrast-enhanced ultrasound could be used to detect vascular disturbances and other information related
to the transplantation of osseous components.
Conclusion:
Bone graft complications can be one of the most devastating consequences of osseous surgery. As surgeons, we are
constantly searching for ways to identify them earlier and prevent them. We hope that by presenting areas that could be
used, we can gain a better insight to ways in which both fields can benefit.
RT-PCR standardization and bone mineralization after low-level laser therapy on adult osteoblast cells
Show abstract
Purpose: Osteoblasts are capable to produce different compounds directly connected to bone mineralization process.
This study aims to standardize the reverse transcriptase polymerase chain reaction (RT-PCR) for adult osteoblasts to
observe the effect of low level laser therapy on bone mineralization. Methods: Five-millimeter long fragments obtained
from the mead femoral region of male Wistar rats were assigned into group A (n=10, laser) and group B (n=10, no laser),
submitted to mechanic and enzymatic digestion. After 7 days, cultures of group A were irradiated daily on a single spot
with a GaInAs laser, λ=808nm, 200mW/cm2, 2J/cm2, bean diameter of 0,02mm, 5 seconds for 6 days. Group B was manipulated but received no laser irradiation. After 13 days the cells were trypsinized for 15 minute and stabilized with RNA later® for RNA extraction with Trizol®. cDNA synthesis used 10μg of RNA and M-MLV® enzyme. PCR was accomplished using the β-actin gene as a control. Another aliquot was fixed for Hematoxylin-Eosin and Von Kossa staining to visualize bone mineralization areas. Results: Under UV light we observed clearly the amplification of β-actin
gene around 400bp. HE and Von Kossa staining showed osteoblast clusters, a higher number of bone cells and well
defined mineralization areas in group A. Conclusion: The cell culture, RNA extraction and RT-PCR method for adult
osteoblasts was effective, allowing to use these methods for bone mineralization studies. Laser improved bone
mineralization and further studies are needed involving osteogenesis, calcium release mechanisms and calcium related
channels.
Radiofrequency ablation for oral and maxillofacial pathologies: A description of the technique
Show abstract
Introduction: Radiofrequency ablation (RFA) refers to a high-frequency current that heats and coagulates tissue. In the
standard RFA setup, three components are used: a generator, an active electrode, and a dispersive electrode. RFA has
garnered support in many of the surgical fields as an alternative to traditional procedures used in tumor removal. Other
methods can prove to be more invasive and disfiguring to the patient, in addition to the unwarranted side effects;
however, RFA provides a more localized treatment, resulting in decreased co-morbidity to the patient. Currently, its use
in the field of oral and maxillofacial surgery is limited, as its technology has not reached our field. By describing its
limited use to the optics community, we hope to expand its uses and provide patients with one more alternative treatment
option.
Methods and Uses: We will describe the use of RFA on three types of pathology: lymphangioma,
rhabdomyoscarcoma, oral squamous cell carcinoma, and neoplastic osseous metastasis. The majority of treatments
geared towards these pathologies involve surgical resection, followed by reconstruction. However, damage to vital
structures coupled with esthetic disfigurement makes RFA a more valuable alternative. In many of the cases, the tumors
were successfully removed without recurrence.
Conclusion: While the use of RFA has been scarce in our field, we believe that with more exposure it can gain
momentum as an alternative to current treatment options. However, there are improvements that we feel can be made,
helping to maximize its effectiveness.
Musculoskeletal Imaging and Diagnostics I
Deep tissue imaging of microfracture and non-displaced fracture of bone using the second and third near-infrared therapeutic windows
Show abstract
Near-infrared (NIR) light in the wavelengths of 700 nm to 2,000 nm has three NIR optical, or therapeutic, windows, which allow for deeper depth penetration in scattering tissue media. Microfractures secondary to repetitive stress, particularly in the lower extremities, are an important problem for military recruits and athletes. They also frequently occur in the elderly, or in patients taking bisphosphonates or denosumab. Microfractures can be early predictors of a major bone fracture. Using the second and third NIR therapeutic windows, we investigated the results from images of chicken bone and human tibial bone with microfractures and non-displaced fractures with and without overlying tissues of various thicknesses. Images of bone with microfractures and non-displaced fractures with tissue show scattering photons in the third NIR window with wavelengths between 1,650 nm and 1,870 nm are diminished and absorption is increased slightly from and second NIR windows. Results from images of fractured bones show the attenuation length of light through tissue in the third optical window to be larger than in the second therapeutic window. Use of these windows may aid in the detection of bone microfractures, and thus reduce the incidence of major bone fracture in susceptible groups.
Musculoskeletal Imaging and Diagnostics II
Infrared fiber optic probes for evaluation of musculoskeletal tissue pathology
Mugdha Padalkar,
Cushla McGoverin,
Quam Onigbanjo,
et al.
Show abstract
Musculoskeletal pathology of the knee commonly occurs with aging and as a result of injury. The incidence of anterior
cruciate ligament (ACL) injuries continues to increase annually, and may precede the eventual onset of osteoarthritis
(OA), a debilitating and prevalent disease characterized by cartilage degeneration. Early detection of OA remains
elusive, with current imaging methods lacking adequate sensitivity to detect early pathologic cartilage changes. We used
mid- and near- infrared (IR) spectroscopy through arthroscopic-based fiber-optic devices to assess cartilage damage and
differentiate tendon from ligament. Mid-IR spectroscopy is characterized by distinct bands and low penetration depth (<
10 μm) and near-IR spectroscopy is characterized by complex overlapping bands and greater penetration depths (< 1
cm). We have found that combined mid- and near-IR analysis greatly extends the information available through either in
the analysis of soft tissues, including cartilage, ligaments and tendons. We discuss here basic science studies and the
potential for translation to clinical research with novel arthroscopic probes.
Photonic hydrogel beads for controlled release of risedronate
Show abstract
pH-sensitive photonic composite hydrogel beads composed of sodium alginate and risedronate sodium (SA/RIS) was
prepared crosslinked by Ca2+ owing to the ionic gelation of SA. The structure and surface morphology of the composite hydrogel beads were characterized by SEM. pH-sensitivity of these composite hydrogels beads and the
release behaviors of drug from them were investigated. The results showed that the composite hydrogel beads had
good pH-sensitivity. The drug loading and encapsulation efficiency were 27.7% and 92% for RIS, respectively. The
cumulative release ratios of RIS from the composite hydrogel beads were 2.47% in pH 2.1 solution and 83 % in pH 6.8 solutions within 24 h, respectively. However, the cumulative release ratio of RIS in pH 7.4 solution reached 91% within 7 h. It is proposed that the novel photonic SA/RIS composite hydrogel bead could possess the potential of an increased intestinal absorption and fewer adverse effects of RIS. The pH and salt response of photonic hydrogel bead,
as well as the encapsulation of macromolecules, are promising for applications in biomedicine and biotechnology.
Bone Spectroscopy and Surgery
Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic analysis of regenerated bone
Show abstract
The cutting of bone is routinely required in medical procedures, especially in dental applications. In such cases, bone
regeneration and new bone quality can determine the success of the treatment. This study investigated the main spectral
differences of undamaged and healed bone using the ATR-FTIR spectroscopy technique. Three rabbits were submitted
to a surgical procedure; a small piece of bone (3x3 mm2) was removed from both sides of their jaws using a high speed
drill. After 15 days, the rabbits were euthanized and the jaws were removed. A bone slice was cut from each side of the
jaw containing regions of undamaged and newly formed bone, resulting in six samples which were polished for
spectroscopic comparison. The samples were analyzed by FTIR spectroscopy using a diamond ATR accessory. Spectral
characteristics were compared and particular attention was paid to the proportion of phosphate to amide I bands and the
width of the phosphate band. The results show that the ratio of phosphate to amide I is smaller in new bone tissue than in
the undamaged bone, indicating a higher organic content in the newly formed bone. The analysis of the width of the
phosphate band suggests a crystallinity difference between both tissues, since the width was higher in the new bone than
in the natural bone. These results suggest that the differences observed in bone aging processes by FTIR spectroscopic
can be applied to the study of healing processes.
Spatial frequencies from human periosteum at different depths using two-photon microscopic images
Show abstract
The outer layer of human bone, the periosteum, was studied using two-photon (2P) fluorescence microscopy. This layer of the periosteum is composed mostly of fibrous collagen. The inner cambium layer has less collagen and contains osteoblasts necessary for bone remodeling. The spatial frequencies from the layers of the periosteum of human bone at different depths were investigated using images acquired with two-photon excitation microscopy. This 2P spectroscopic method offers deeper depth penetration into samples, high fluorescence collection efficiency, and a reduction in photobleaching and photodamage. Using 130 femtosecond pulses with an 800 nm wavelength excitation, a 40× microscope objective, and a photomultiplier tube (PMT) detector, high contrast images of the collagen present in the periosteum at various micrometers depths from the surface were obtained. Fourier transform analysis of the 2P images was used to assess the structure of the periosteum at different depths in terms of spatial frequencies. The spatial frequency spectra from the outer and inner periosteal regions show significant spectral peak differences which can provide information on the structure of the layers of the periosteum. One may be able to use spatial frequency spectra for optical detection of abnormalities of the periosteum which can occur in disease.
Photoacoustic and ultrasound dual-modality imaging for inflammatory arthritis
Show abstract
Arthritis is a leading cause of disability, affecting 46 million of the population in the U.S. Rendering new optical contrast
in articular tissues at high spatial and temporal resolution, emerging photoacoustic imaging (PAI) combined with more
established ultrasound (US) imaging technologies provides unique opportunities for diagnosis and treatment monitoring
of inflammatory arthritis. In addition to capturing peripheral bone and soft tissue images, PAI has the capability to
quantify hemodynamic properties including regional blood oxygenation and blood volume, both abnormal in synovial
tissues affected by arthritis. Therefore, PAI, especially when performed together with US, should be of considerable help
for further understanding the pathophysiology of arthritis as well as assisting in therapeutic decisions, including
assessing the efficacy of new pharmacological therapies. In this paper, we will review our recent work on the
development of PAI for application to the diagnostic imaging and therapeutic monitoring of inflammatory arthritis. We
will present the imaging results from a home-built imaging system and another one based on a commercial US. The
performance of PAI in evaluating pharmacological therapy on animal model of arthritis will be shown. Moreover, our
resent work on PAI and US dual-modality imaging of human peripheral joints in vivo will also be presented.