Funding for a """"""""body"""""""" gradient set and its associated gradient and shim drivers are sought for improved performance for a 4 Tesla/90 cm MR instrument used for high magnetic field human spectroscopy and imaging research. 4 Tesla high field MR systems for human studies were introduced in 1991 for the first time in three different academic laboratories in the United States one of which was our lab, the Center for Magnetic Resonance Research (CMRR), University of Minnesota. Since then, rapid methodological developments in data acquisition and optimization demonstrated the usefulness of such high fields in biomedical research leading to ever increasing interest in these instruments as research tools. One of the major limitations of these high field instruments has been the performance of the gradients for spatial encoding and """"""""shims"""""""" for homogenizing the magnetic field. All of these high-field instruments have so far been equipped with gradients that were originally designed for 1.5 Tesla clinical MR imagers; in addition, these gradient sets were early designs even for 1.5 Tesla instruments and do not possess improved design, manufacturing, and ultimately the performance that are becoming available in 1.5 Tesla systems. In addition, we have established a quantitative understanding of the stringent shimming requirements at high fields which permits us to define the shim performance criteria that are simply not met in gradient sets originally designed for 1.5 Tesla clinical imaging systems. If advantages that are provided by high magnetic fields are to be fully exploited, going to better gradient performance that also provide convenience of use and subject/patient comfort and tolerance is imperative. The proposed upgrade will impact a large body of NIH funded grants that focus on. developing and/or using high magnetic fields for biomedical research.
