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Fast limited flip angle mr subtraction angiography
Author(s) -
Tasciyan Talin A.,
Lee James N.,
Riederer Stephen J.,
Decastro Jose B.,
Hedlund Laurence W.,
Herfkens Robert J.,
Spritzer Charles E.
Publication year - 1988
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.1910080304
Subject(s) - flip angle , cardiac cycle , diastole , subtraction , pulsatile flow , systole , coherence (philosophical gambling strategy) , blood flow , nuclear magnetic resonance , physics , biomedical engineering , materials science , nuclear medicine , mathematics , medicine , radiology , cardiology , magnetic resonance imaging , blood pressure , arithmetic , quantum mechanics
A fast MR angiography method is introduced that is capable of generating difference images of blood vessels in scan times of 10–20 s. This is an order of magnitude faster than many previous methods. The fundamental concept ofthis approach is to use cardiac gating and acquire several phase encodings at least twice during each cardiac cycle using limited flip angles (LFAs) and repetition times in the 20 to 50 ms range. The encodings acquired during diastole are subtracted from those acquired during systole to generate the difference image. The contrast in the difference image is due both to the influx of unsaturated spins and to the loss of phase coherence of systolic blood moving at high velocity along a magnetic gradient. The systolic peak of the cardiac cycle is determined during reconstruction by shifting the systolic and diastolic “windows” until the difference signal is maximized. Ghost artifacts due to pulsatile flow are eliminated by a phase reordering technique similar in concept to those developed for suppression of breathing artifacts. Arteries in thick slices are successfully imaged and initial in vivo results are presented. © 1988 Academic Press, Inc.