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Nuclear magnetic resonance signal from flowing nuclei in rapid imaging using gradient echoes
Author(s) -
Gao JiaHong,
Holland Scott K.,
Gore John C.
Publication year - 1988
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.596197
Subject(s) - nuclear magnetic resonance , magnetic resonance imaging , physics , medical imaging , signal (programming language) , materials science , optics , radiology , medicine , computer science , programming language
A theoretical description of the nuclear magnetic resonance (NMR) signal from flowing nuclei has been developed for rapid imaging sequences that use small flip angles and gradient refocused echoes. Both laminar and plug flow models have been considered and formulas derived relating mean image signal intensity to flip angle, pulse sequence repetition interval ( T R ), and flow velocity. It is shown that the rate of approach to steady‐state conditions determines the degree of flow enhancement. Experimental measurements have been performed on a flow phantom in a whole‐body NMR imaging system operating at 0.15 T using the spoiled FLASH sequence with different radiofrequency pulse flip angles and flow rates. There is excellent agreement between the experimental results and the theoretical predictions up to the onset of turbulence.