Quantitative whole body imaging at high field

In this thesis methods of accurately and reproducibly measuring intestinal content and transverse relaxation to study the fate of food in the gastrointestinal tract are reported. In addition to this a technique for measuring relaxation parameters in the brain at ultra-high field is also investigated. Several methods can be used when quantifying the fate of food through the gastrointestinal tract; there are many factors that can be measured using MRI and these are discussed along with other non-MRI techniques. In this work a method for quantifying small bowel water content (SBWC) is optimised and validated for use at 3.0 T and a technique for measuring T2 in the abdomen is developed and optimised called T2-prepared balanced turbo field echo (T2-prep bTFE). These two methods are then used, in conjunction with other established MRI techniques, to study the fate of food in the gastrointestinal tract from the stomach all the way through to the colon. A hybrid gradient echo-spin echo (GESSE) sequence is also investigated and optimised for measuring T2 and T2* simultaneously in the brain at 7.0 T. This sequence is also proved to have applications in the liver at lower field strengths. The GESSE sequence is used to measure the first T2 values in deep grey structures in the brain at 7.0 T. In this work cross-field (1.5, 3.0 and 7.0 T) variations in T2 are studied. Also differences in T2 and T2* are measured in the brain to determine variations between white matter tracts and to ascertain any effects of Parkinson’s disease on deep grey matter structures.