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Fast phase‐contrast velocity measurement in the steady state
Author(s) -
Overall William R.,
Nishimura Dwight G.,
Hu Bob S.
Publication year - 2002
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.10285
Subject(s) - steady state free precession imaging , steady state (chemistry) , precession , contrast (vision) , imaging phantom , nuclear magnetic resonance , image quality , phase (matter) , physics , signal (programming language) , signal to noise ratio (imaging) , noise (video) , mathematics , optics , magnetic resonance imaging , chemistry , computer science , image (mathematics) , radiology , medicine , artificial intelligence , quantum mechanics , astronomy , programming language
A new method of encoding flow velocity as image phase in a refocused steady‐state free precession (SSFP) sequence, called steady‐state phase contrast (SSPC), can be used to generate velocity images rapidly while retaining high signal. Magnitude images with refocused‐SSFP contrast are simultaneously acquired. This technique is compared with the standard method of RF‐spoiled phase contrast (PC), and is found to have more than double the phase‐signal to phase‐noise ratio (PNR) when compared with standard PC at reasonable repetition intervals (TRs). As TR decreases, this advantage increases exponentially, facilitating rapid scans with high PNR efficiency. Rapid switching between the two necessary steady states can be accomplished by the insertion of a single TR interval with no flow‐encoding gradient. The technique is implemented in a 2DFT sequence and validated in a phantom study. Preliminary results indicate that further TR reduction may be necessary for high‐quality cardiac images; however, images in more stationary structures, such as the descending aorta and carotid bifurcation, exhibit good signal‐to‐noise ratio (SNR) and PNR. Comparisons with standard‐PC images verify the PNR advantage predicted by theory. Magn Reson Med 48:890–898, 2002. © 2002 Wiley‐Liss, Inc.