Radiation force elastography and optoacoustic imaging for assisting cancer detection and treatment
Supervisor(s): Dr Jeff Bamber
Ultrasound and Optical Imaging Team
As a team we have had a considerable programme of work running over the past decade in developing a new imaging method known as ultrasound elastography [1]. This usually works by applying a stress (i.e., force) to the surface of the body, and using ultrasound images to calculate the resulting distribution of strain (i.e. deformation) inside the body. The images can be interpreted in terms of information about tissue stiffness, which may help in many areas of medicine, such as detecting and diagnosing cancer, or guiding tumour treatment. The technique is beginning to be widely available on commercial ultrasound scanners. We are also making good progress with an approach to elastography that aims to overcome the fact that a force applied to the body surface gets redistributed at depth by the stiffness variations within the body, or may be dissipated at mechanical discontinuities such as surgical incisions. Instead of applying the force at the surface, it is placed deep within the body using a sound field that creates a focused and transient radiation force (a kind of “acoustic wind”) that it is largely not influenced by neighbouring stiffness variations [2,3]. Finally, we are currently working with European partners in a multi-institutional project to produce and evaluate an optoacoustic imaging system. This builds on previous work in optoacoustic imaging [4], a technique that uses passive ultrasound imaging to visualise acoustic emissions that result from the heat generated by absorption of pulsed laser radiation. Such images show optical absorption information, but with the resolution of ultrasound (optical resolution is normally very poor in vivo due to the strong scattering of light by tissue).
Ultrasound, elastographic, and optoacoustic images have the potential to provide a powerful combination of highly complementary information, and may be produced in registration, simultaneously, using a single set of hardware. Eventual applications include functional and targeted molecular imaging for cancer diagnosis and monitoring, and selection of patients suitable for specific treatments. A particular current interest of ours, to which these methods are highly applicable, is intraoperative imaging in neurosurgery, where it would be helpful to detect residual tumour and thus ensure complete tumour resection.
This PhD project is about turning the above group of methods, which exist individually in research form, into a combination that is more clinically and widely useful, by implementing them on an existing commercial ultrasound scanner. It requires the cooperation of an industrial partner who produces a suitably-adaptable ultrasound scanner, which we have, and for the student to take on the task of modifying the scanner to produce radiation force elasticity images and optoacoustic images in an optimal manner. Optimisation will be achieved by a combination of computer modelling and engineering design, and experiments to assess actual performance. The student will benefit from working alongside others in the ultrasound and optics team, who are also working on radiation force elastography and optoacoustic imaging. If time permits, opportunities will also be available to work with medical doctors to test the potential clinical value of the system, and to investigate novel optoacoustic contrast agents.
