Photoacoustic imaging of head and neck cancer
Allocated in Academic Year 2016-2017
Lymph nodes are a foremost site of metastasis in many cancers and establishing their level of involvement is important for disease staging, prognosis and treatment planning. Extranodal spread – breaching of the lymph node boundary by cancer – and the formation of new blood vessels can be indicators of cancer but are difficult to detect in vivo using established clinical imaging modalities such as CT, MRI and ultrasound. As a consequence, many clinical situations require histopathological assessment following biopsy, which is necessarily invasive and can lead to complications. Photoacoustic imaging is an emerging modality that relies on exciting high frequency sound waves in tissue by the absorption of nanosecond laser pulses. The generated sound waves are then detected and used to reconstruct a picture of the absorbed optical energy from which a high resolution 3D image of the internal tissue structure can be recovered. Photoacoustic imaging offers the prospect of directly visualising the formation of new blood vessels that are indicative of cancer as well as distortion of the nodal boundary via lipid contrast arising from internal tumour spreading. As a consequence it could overcome the limitations of existing medical imaging techniques and provide a wholly non invasive clinical assessment of lymph nodes.
The aim of the project is to explore the potential of photoacoustic imaging for this clinical application by developing and evaluating a novel photoacoustic scanner optimised for head and neck cancer imaging. The project will involve a significant experimental component comprising the development of an optical fibre system for delivering the excitation laser pulses, a novel ultrasound detection scheme for acquiring photoacoustic signals and evaluation via preliminary clinical studies. There will also be an opportunity to contribute to the development of new image reconstruction algorithms and signal processing techniques.
The project is centred on the development of a novel imaging technique for the clinical assessment of head and neck nodal metastases. This offers the prospect of identifying appropriate disease related biomarkers and providing an earlier and more specific diagnosis as well as improved treatment monitoring. As such, it aligns within the clinical research theme of cancer imaging. Although the emphasis will be on the clinical assessment of head and neck nodal metastasis, the technology could also find application in the assessment of other superficial cancers such as those of the skin. The project will involve significant hardware development at both component and systems level and thus aligns with the imaging device methodological research theme.