NMR SIGNAL FROM FLOWING NUCLEI IN FAST GRADIENT-ECHO PULSE SEQUENCES WITH REFOCUSING

A theoretical description of the nuclear magnetic resonance (NMR) signal from Bowing nuclei in refocused gradient-echo pulse sequences, both with continuous- and alternating-phase pulse trains, has been developed. Both laminar and plug flow models have been considered and formulae have been derived that relate mean signal intensity to flip angle, pulse sequence repetition interval (TR), and flow velocity. The degree of signal enhancement or reduction in various conditions of flow and pulse sequences depends on the precise phase relationships between the residual transverse magnetization and each radio-frequency (RF) pulse.