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Dynamic per slice shimming for simultaneous brain and spinal cord fMRI
Author(s) -
Islam Haisam,
Law Christine S. W.,
Weber Kenneth A.,
Mackey Sean C.,
Glover Gary H.
Publication year - 2019
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.27388
Subject(s) - spinal cord , shim (computing) , lumbar spinal cord , neuroscience , functional magnetic resonance imaging , central nervous system , magnetic resonance imaging , computer science , medicine , psychology , radiology , erectile dysfunction
Purpose Simultaneous brain and spinal cord functional MRI is emerging as a new tool to study the central nervous system but is challenging. Poor B 0 homogeneity and small size of the spinal cord are principal obstacles to this nascent technology. Here we extend a dynamic shimming approach, first posed by Finsterbusch, by shimming per slice for both the brain and spinal cord. Methods We shim dynamically by a simple and fast optimization of linear field gradients and frequency offset separately for each slice in order to minimize off‐resonance for both the brain and spinal cord. Simultaneous acquisition of brain and spinal cord fMRI is achieved with high spatial resolution in the spinal cord by means of an echo‐planar RF pulse for reduced FOV. Brain slice acquisition is full FOV. Results T2*‐weighted images of brain and spinal cord are acquired with high clarity and minimal observable image artifacts. Fist‐clenching fMRI experiments reveal task‐consistent activation in motor cortices, cerebellum, and C6‐T1 spinal segments. Conclusions High quality functional results are obtained for a sensory‐motor task. Consistent activation in both the brain and spinal cord is observed at individual levels, not only at group level. Because reduced FOV excitation is applicable to any spinal cord section, future continuation of these methods holds great potential.