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Single‐shot EPI with signal recovery from the susceptibility‐induced losses
Author(s) -
Song Allen W.
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.1205
Subject(s) - signal (programming language) , computer science , temporal resolution , functional magnetic resonance imaging , magnetic resonance imaging , gradient echo , echo (communications protocol) , nuclear magnetic resonance , physics , neuroscience , optics , psychology , medicine , computer network , radiology , programming language
A major problem in the gradient‐recalled echo‐planar imaging (EPI) method that also uses a long echo time (TE) is the severe signal loss in regions with large static field inhomogeneities. These regions include the ventral frontal, medial temporal, and inferior temporal lobes, which experience inhomogeneities induced by susceptibility effects commonly found near air/tissue interfaces. For functional magnetic resonance imaging (fMRI) studies that use both gradient‐recalled EPI at relatively long TE and high‐field scanners, this signal loss is severe, preventing investigation of certain human cognitive processes that involve these regions, such as memory and attention. Methods have been developed to recover this signal loss; however, most of them require multiple excitations and thus compromise temporal resolution. In this report, a new technique is described which achieves good signal recovery within a single excitation. It is anticipated that this technique will prove useful for fMRI studies in inhomogeneous areas that require high temporal resolution. Magn Reson Med 46:407–411, 2001. © 2001 Wiley‐Liss, Inc.