LONG-TERM OBJECTIVES 1. To calculate magnetic field profiles of NMR coils of different geometries, and the signal detected by them from different regions in space with various pulse sequences. 2. To use this information to design tailor-made NMR coils with good homogeneity and spatial selectivity properties for specific in vivo organs and tissue. This will hopefully allow better discrimination of signal from desired tissue vs. undesired tissue, better signal-to-noise ratio, and more reliable measurements of relaxation times and kinetics.
SPECIFIC AIMS 1. To calculate and graphically display radiofrequency magnetic field profiles and contours generated by NMR coils of various geometries. To calculate and display signal intensities obtained from different regions of a sample with these coils using different commonly employed pulse sequences as a function of RF power and pulse duration and inter-pulse delay time. 2. To use such information to design transmitter and receiver coils with desired properties of field homogeneity, spatial selectivity, and sensitivity for applications in in vivo biological nuclear magnetic resonance (NMR). 3. To verify these calculations with experimental data from phantom samples and coils constructed to geometrical specifications suggested by theory. 4. To build coils of successful geometries to be compatible with in vivo physiology and anatomy, and apply them to study metabolism. METHODOLOGY 1. Write software to perform the calculations and graphics displays on a VAX 11/780, using the Biot Law. 2. Construct coils from materials selected for biocompatibility and electromagnetic performance. Measure induced fields on bench with synthesizer, oscilloscope, and search coil. Measure S/N on spectrometer with phantoms at different spatial locations. 3. Apply coils to study of in vivo metabolism of selected organs, viz., brain, heart, and kidney.
