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Proceedings Paper

Radio-frequency ablation monitoring through real-time, video-rate all-optical ultrasound imaging (Conference Presentation)

Paper Abstract

Radiofrequency ablation is widely used in cardiology as an effective minimally invasive treatment for atrial fibrillation. However, radiofrequency noise, electronic interference, low resolution and poor tissue contrast complicate real-time lesion monitoring using conventional imaging modalities such as magnetic resonance imaging or ultrasound imaging based on electronic transducers. Recently, a bench-top all-optical ultrasound imaging system, where ultrasound is both generated and detected using light, was presented (doi:10.1364/BOE.9.003481) that achieved high-resolution, video-rate 2D images. In this system, pulsed excitation light was focussed onto a nanocomposite membrane, where it was converted into ultrasound via the photoacoustic effect. Using scanning optics, the resulting optical ultrasound source was translated to synthesise a 1D source aperture comprising irregularly spaced ultrasound sources. Back-scattered ultrasound was detected using a single fibre-optic Fabry-Pérot cavity. Here, this system (which is inherently insensitive to electromagnetic interference) was used to achieve the first video-rate, depth-resolved 2D images acquired during RF ablation using an all-optical ultrasound imaging setup. We used this system to monitor the formation of radiofrequency ablation lesions (max 30 W, 65°C, 60 s) in ex vivo chicken breast samples, at a frame rate of 9 Hz, resolution of 100 µm, an imaging depth >15 mm, and a contrast of up to 30 dB. With its high miniaturisation potential, all-optical ultrasound imaging shows great promise for guiding interventional procedures, where real-time ablation lesion visualisation could improve lesion delivery and patient outcome.

Paper Details

Date Published: 4 March 2019
Proc. SPIE 10855, Diagnostic and Therapeutic Applications of Light in Cardiology 2019, 108550M (4 March 2019);
Show Author Affiliations
Erwin J. Alles, Univ. College London (United Kingdom)
Richard J. Colchester, Univ. College London (United Kingdom)
Sacha Noimark, Univ. College London (United Kingdom)
Edward Z. Zhang, Univ. College London (United Kingdom)
Paul C. Beard, Univ. College London (United Kingdom)
Malcolm C. Finlay, Barts Heart Ctr., Queen Mary Univ. of London (United Kingdom)
Univ. College London (United Kingdom)
Adrien E. Desjardins, Univ. College London (United Kingdom)

Published in SPIE Proceedings Vol. 10855:
Diagnostic and Therapeutic Applications of Light in Cardiology 2019
Kenton W. Gregory M.D.; Laura Marcu, Editor(s)

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