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A strategy to optimize the signal‐to‐noise ratio in one‐coil arterial spin tagging perfusion imaging
Author(s) -
Lei Hao,
Peeling James
Publication year - 1999
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/(sici)1522-2594(199903)41:3<563::aid-mrm20>3.0.co;2-6
Subject(s) - nuclear magnetic resonance , magnetization transfer , offset (computer science) , perfusion , radiofrequency coil , magnetic resonance imaging , arterial spin labeling , signal (programming language) , electromagnetic coil , physics , radio frequency , magnetization , perfusion scanning , pulse (music) , signal to noise ratio (imaging) , noise (video) , chemistry , materials science , optics , magnetic field , computer science , image (mathematics) , medicine , radiology , telecommunications , quantum mechanics , artificial intelligence , detector , programming language
The signal‐to‐noise ratio of the perfusion image (SNR perfu ) in a spin‐tagging experiment is shown to depend on both the degree of spin labeling (α) and the signal‐to‐noise ratio of the proton density images (SNR image ) used to calculate the perfusion image. When a single radiofrequency (RF) coil is used for both spin tagging and magnetic resonance (MR) imaging, magnetization transfer (MT) effects decrease SNR image , and therefore SNR perfu , by an amount that depends on the strength B 1 and offset Δω (determined by the gradient strength G l applied during spin tagging) of the labeling RF pulse. It is shown that by optimizing B 1 and G l , it is possible to reduce MT effects and thus increase SNR image , while leaving α unchanged. As a result, SNR perfu will be improved. An equation for calculating perfusion under general conditions of such reduced MT effects is derived and shown to give perfusion rates that are independent of the strength and offset of the labeling RF irradiation. Magn Reson Med 41:563–568, 1999. © 1999 Wiley‐Liss, Inc.