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Background suppression using magnetization preparation for contrast‐enhanced MR projection angiography
Author(s) -
Bos Clemens,
Bakker Chris J.G.,
Viergever Max A.
Publication year - 2001
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.1162
Subject(s) - contrast (vision) , magnetization , subtraction , nuclear magnetic resonance , materials science , signal (programming language) , magnetization transfer , pulse sequence , excitation , projection (relational algebra) , biomedical engineering , nuclear medicine , optics , physics , mathematics , magnetic resonance imaging , medicine , radiology , computer science , algorithm , magnetic field , arithmetic , quantum mechanics , programming language
In contrast‐enhanced MR projection angiography, vessel conspicuity is determined by the T 1 ‐weighted signal difference between blood and surrounding tissues. For slice‐selective excitation pulses, the excitation angle varies across the slice, leading to poor saturation of the background signal at the slice edge and reducing the blood‐background signal difference. This work reports on the use of magnetization preparation to enhance the T 1 ‐weighted contrast between blood and background tissue. Applying the prepulse nonselectively reduces the influence of the slice profile imperfections of the excitation pulse by keeping the background tissue at the slice edge saturated. Analytical calculations and in vitro experiments show that a prepulse angle of 110°–130° and a delay time of 20–25 ms enhance the contrast between contrast‐enhanced blood ( T 1 < 50 ms) and background tissues ( T 1 > 200 ms), and improve the slice weighting profile. Magnetization preparation is shown to effectively suppress signal from background tissue, resulting in a threefold increase of the vessel‐to‐background signal ratio. Magnetization preparation eliminates the need for subtraction at the cost of a slight increase in scan time. Possible applications, such as projection MRA, detection of contrast arrival, and test‐bolus tracking are demonstrated in a pig model. Magn Reson Med 46:78–87, 2001. © 2001 Wiley‐Liss, Inc.