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Sensitivity‐encoded (SENSE) proton echo‐planar spectroscopic imaging (PEPSI) in the human brain
Author(s) -
Lin FaHsuan,
Tsai ShangYueh,
Otazo Ricardo,
Caprihan Arvind,
Wald Lawrence L.,
Belliveau John W.,
Posse Stefan
Publication year - 2007
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.21119
Subject(s) - magnetic resonance spectroscopic imaging , nuclear magnetic resonance , sensitivity (control systems) , magnetic resonance imaging , physics , computer science , materials science , chemistry , optics , medicine , engineering , radiology , electronic engineering
Magnetic resonance spectroscopic imaging (MRSI) provides spatially resolved metabolite information that is invaluable for both neuroscience studies and clinical applications. However, lengthy data acquisition times, which are a result of time‐consuming phase encoding, represent a major challenge for MRSI. Fast MRSI pulse sequences that use echo‐planar readout gradients, such as proton echo‐planar spectroscopic imaging (PEPSI), are capable of fast spectral‐spatial encoding and thus enable acceleration of image acquisition times. Combining PEPSI with recent advances in parallel MRI utilizing RF coil arrays can further accelerate MRSI data acquisition. Here we investigate the feasibility of ultrafast spectroscopic imaging at high field (3T and 4T) by combining PEPSI with sensitivity‐encoded (SENSE) MRI using eight‐channel head coil arrays. We show that the acquisition of single‐average SENSE‐PEPSI data at a short TE (15 ms) can be accelerated to 32 s or less, depending on the field strength, to obtain metabolic images of choline (Cho), creatine (Cre), N‐acetyl‐aspartate (NAA), and J‐coupled metabolites (e.g., glutamate (Glu) and inositol (Ino)) with acceptable spectral quality and localization. The experimentally measured reductions in signal‐to‐noise ratio (SNR) and Cramer‐Rao lower bounds (CRLBs) of metabolite resonances were well explained by both the g ‐factor and reduced measurement times. Thus, this technology is a promising means of reducing the scan times of 3D acquisitions and time‐resolved 2D measurements. Magn Reson Med 57:249–257, 2007. © 2007 Wiley‐Liss, Inc.