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Details of Grant 

EPSRC Reference: EP/C536118/1
Title: Development of a 3D photoacoustic scanner for in vivo high resolution anatomical, physiological and molecular imaging in small animals
Principal Investigator: Beard, Professor PC
Other Investigators:
Elwell, Professor CE Delpy, Professor DT Laufer, Dr J
Zhang, Dr EZ
Researcher Co-Investigators:
Project Partners:
Department: Medical Physics and Biomedical Eng
Organisation: UCL
Scheme: Standard Research (Pre-FEC)
Starts: 21 November 2005 Ends: 20 May 2009 Value (£): 571,267
EPSRC Research Topic Classifications:
Instrumentation Eng. & Dev.
EPSRC Industrial Sector Classifications:
Healthcare
Related Grants:
Panel History:  
Summary on Grant Application Form
A major problem in many physiological measurements is that the act of performing the measurement can itself alter the system that is under observation. The challenge for medical physicists is to develop techniques which allow the non invasive assessment of physiological processes. The aim of the work described in this proposal is to built a novel non invasive imaging system which will provide very detailed pictures of the processes happening within the body, from the concentration of oxygen in blood vessels all the way down to characterising the behaviour of specific genes which may play an important role in brain damage and cardiac disorders.The instrument we propose to develop is called a photoacoustic (PA) imaging system which combines the techniques of optical spectroscopy with ultrasound. Optical spectroscopy uses measurements of light absorption to measure the colour of blood and therefore its oxygen content (highly oxygenated arterial blood is bright red whilst oxygen depleted venous blood appears purple/blue in colour). Ultrasound produces highly detailed images of tissue structure by measuring the intensity and timing of echos produced by firing high frequency sound waves into tissue. These techniques can be combined in photoacoustic imaging where very short pulses of light are fired into tissue and are absorbed by structures such as blood vessels. When the optical energy is deposited in the tissue there is a small heating effect which leads to the transient thermal expansion of the absorbing structures. This expansion generates an acoustic shock wave which travels though the tissue back to the surface. By measuring time of arrival of these acoustic waves at a number of detectors positioned around the tissue, and with knowledge of the speed of sound in tissue, the acoustic signals can be combined and backprojected to produce a 3D image of the internal absorbing structures within the tissue. The technique is very powerful because it combines spectroscopic information with high spatial resolution available to ultrasound.We propose to build a novel photoacoustic imaging system specifically for use in studies on small laboratory animals. Small animals such as mice are used to model a very wide range of diseases and it is very important to develop methods of non invasively imaging the disease processes in these animals. In this application we are interested in imaging processes associated with two clinical applications; (i) brain damage in newborn infants which can lead to a number of long term neurological disorders including cerebral palsy, and (ii) atherosclerosis, or furring up of blood vessels which can lead to a number of disorders of the cardiovascular system.The project will involve the design and construction of a small animal photoacoustic imaging system, which will take the form of an entirely novel and transparent Perspex cube. The transparent nature of the imaging cube will enable it to be easily combined with other imaging modalities such as magnetic resonance imaging, positron emission tomography and fluorescent and bioluminescence systems. Initially the PA instrument will be used to map oxygen distribution in a model of neonatal brain injury. However one of the most exciting features of this system will be its ability to image much more specific molecular processes in tissue, so called molecular imaging. Optical probes which strongly absorb the wavelengths of light emitted by the PA system will be tagged to specific molecules either in the mouse brain or throughout the whole body. These optical probes will act as markers of cellular activity and when imaged by the PA system will indicate, for example, the level of cell damage following an induced injury mimicking that seen in a newborn infant. In addition it should be possible to use these optical probes to track specific gene activity in genetically modified animals and hence extend the technique to the exciting new field of genomic imaging.
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