Photoacoustic imaging (PAI) enables the acquisition of images based on optical contrast with a spatial resolution and penetration depth approaching that of ultrasound. Absorption of a nanosecond laser pulse by tissue generates a thermoelastic expansion and results in a detectable ultrasound wave. The differential optical absorption of oxy- and deoxy-haemoglobin enable spectral unmixing of blood haemoglobin concentration and oxygenation in tissue. Emerging evidence suggests that we can exploit this capability of PAI to assess tissue vascular function without the need for injectable contrast. Moreover, as PAI is a relatively low cost imaging modality that can be combined with existing ultrasound systems, it holds significant potential as a future clinical tool.

We are working on the technical and biological validation of novel experimental and computational methods for PAI that provide new opportunities for evaluating cancer prognosis. This includes the use of light fluence models relevant for application in vivo as well as standardised protocols for contrast enhancement in tumour tissue. A major area of research includes the development of new tissue mimicking phantoms and test methods for standardisation in photoacoustics, which is conducted through IPASC. New contrast agents are also under development to provide specific signals for biological processes that do not intrinsically generate optically absorbing molecules within cells. By applying these well validated PAI methods in small animal models and in patients, our aim is to generate new insight into process of vessel formation in tumour evolution and mechanisms of response to novel anti-angiogenic therapies.

Exemplar PAI tomography images depicting the response of a prostate tumour to (A) an oxygen breathing gas challenge to reveal tumour hypoxia and (B) perfusion of an optically absorbing contrast agent to identify perfusion. M R Tomaszewski et al (2018) Cancer Research.

Lab members:

Emma Brown, Thomas Else, Lina HackerDr James Joseph, Dr Paul Sweeney.


Prof. Carlos Caldas, Prof. Greg Hannon, Prof. Patrick Chinnery, Prof. Rita Horvath (University of Cambridge, UK)

Dr Silvia Hernandez-Ainsa (University of Zaratoga, Spain); Prof. Daniel Razansky (ETH/University of Zurich, Switzerland).