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Photoacoustic imaging is a novel hybrid imaging modality that relies on the generation of ultrasound waves by the absorption of short laser pulses in biological tissue. Its fundamental advantage derives from the fact that it encodes tissue optical absorption on to ultrasonic waves which are minimally scattered in soft tissues. It thus provides both the high spectrally selective contrast of optical imaging techniques and the high resolution of ultrasound.
Photoacoustic imaging is particularly well suited to visualising vascular anatomy due to the strong absorption exhibited by haemoglobin. As a consequence, it provides significantly higher label-free vascular contrast than existing imaging modalities such as ultrasound. This offers new opportunities for delineating tumour margins to aid cancer treatment planning, identifying major blood vessels to help guide fetal or laparoscopic surgery and monitoring minimally invasive ablative therapies used in cardiovascular medicine.
Whilst the advances in PA imaging are encouraging, image quality for many clinical applications can be limited by the natural variation in the sound speed between tissue types. The variations aberrate the photoacoustic waves passing through the tissue, resulting in artefacts and blurring in the image. Incorporating additional information about the sound speed variations in the image reconstruction algorithm is expected to improve the image quality.
The outcome of the project will be an image reconstruction framework that provides improved image fidelity and resolution by accounting for sound speed variations. This will be benefit almost any clinical application of PA imaging by enabling the visualisation of previously indistinguishable anatomical structures and providing a more accurate representation of their morphology; for example, it will provide more precise visualisation of tumour margins yielding more accurate guidance of their surgical excision in laparoscopic liver surgery. More accurate image reconstruction will also contribute to the development of functional photoacoustic imaging for which high spatial fidelity is an essential prerequisite and currently a limiting factor.
The project will involve working with acoustic propagation models, the development of novel image reconstruction methods and their computation implementation as well as generating and/or working with measured data acquired through laboratory and clinical studies. It will suit students with an interest in wave physics, computational methods and a desire to see their work translated to practical application in medicine.
Supervisors
Professor Paul Beard
Dr Andrew Plumb
Dr Ben Cox / Dr Bradley Treeby