SQUID DETECTED NMR AND MRI AT ULTRALOW FIELDS

摘要

Nuclear magnetic resonance signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device 'SQUID' (31) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio 'SNR' and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields.