Title: Exploiting the unique quantitative capabilities offered by simultaneous PET/MRI
Funder: Engineering and Physical Sciences Research Council

Abstract: Both positron emission tomography (PET) and magnetic resonance imaging (MRI) are well-developed imaging methods that provide key diagnostic information in clinical studies. PET can detect very small quantities of radiolabelled tracers which illustrates ways in which the body functions and what is happening to cells and small molecules in the body. However, PET images have poor spatial resolution and can only be acquired in a relatively long time (several minutes). On the other hand, MRI provides high spatial and temporal resolution anatomical information unrivalled by any other imaging modalities, especially providing excellent soft-tissue contrast. It is widely recognized that imaging systems that incorporate two different imaging methods can add diagnostic value e.g. PET/CT. The UK's first simultaneous whole body PET/MRI system was recently installed at UCL/UCH providing a unique platform for cutting edge research. We aim to exploit the simultaneous capability of this unique instrument to improve the range of parameters available for clinical interpretation. Our research programme will involve the following novel sub-projects. a) We will take advantage of MRI anatomical and functional information to directly improve the accuracy and precision of PET reconstruction. This involves development of computer programs that can extract information on organ boundaries from MRI and use this information to control the PET reconstruction. In kinetic studies, where a time sequence of images is acquired, knowledge of the expected changes in time can also be used to improve image quality. b) We will develop an efficient method for MRI motion estimation that can be applied for correction of simultaneously acquired PET data, in a practical setting. This involves the development of new methods of acquiring MRI data so that motion can be measured along with the standard methods that are required for clinical acquisition. The information on motion will be incorporated in the software used for the PET reconstruction. c) We will develop joint solutions for simultaneously acquired PET and MRI kinetic data that has potential to benefit both modalities. A number of useful parameters can be extracted from dynamic studies performed either using PET or MRI, but there are usually quite large errors involved. No-one has previously used the information available from both techniques to improve the estimation of parameters. This is quite challenging but will permit the measurement of more specific parameters that may be more helpful in understanding disease and its treatment. d) We will adopt an all-inclusive framework for PET reconstruction that encompasses the complementary MRI information: spatial information, motion estimation and kinetic models. This will attempt to utilize all the available information to improve the PET image quality and the reliability of quantitative parameters that can be made available to clinicians. We hope to extend this approach to a truly combined reconstruction of parameters using information from both modalities. The proposed research necessarily involves a multidisciplinary team of researchers with complementary skills, who are well placed to direct the research to meet well defined goals. The developed techniques will be evaluated in patient studies performed on the new PET/MRI system as a basis for their future use in clinical research.


Research activity codes: 4.1 DISCOVERY AND PRECLINICAL TESTING OF MARKERS AND TECHNOLOGIES
Health categories: GENERIC HEALTH RELEVANCE