On the performance of tubular surface coils in nuclear magnetic resonance imaging and spectroscopy

Surface coils are important devices in the clinical application of nuclear magnetic resonance imaging and spectroscopy (NMRIS) because they have higher signal-to-noise ratios than body or head coils in superficial regions. This paper describes our theoretical and experimental study of the performances of tubular surface coils, aiding the effective application of such coils to NMRIS. We present formulas for the RF magnetic (H/sub 1/) fields produced by tabular surface coils placed over layered media, and for the self- and loaded-impedances of these coils. The calculated results show the dependence of the coil performances on the coil design parameters and the characteristics of the sample under test. We include the calculated results for the H/sub 1/ field phase shifts in conductive samples.<
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