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Local in vivo shimming using adaptive passive shim positioning

✍ Scribed by Sejung Yang; Hahnsung Kim; Min-Oh Ghim; Byung-Uk Lee; Dong-Hyun Kim

Publisher
Elsevier Science
Year
2011
Tongue
English
Weight
902 KB
Volume
29
Category
Article
ISSN
0730-725X

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✦ Synopsis

A subject-specific local in vivo passive shimming method, focusing on the prefrontal and temporal regions, is proposed. The aim of the investigation is to show that subject variability exists in optimal passive shimming and that the proposed method can be effectively used to overcome these differences. A shimming structure capable of adjusting the position of the passive shims to within a millimeter resolution is built. The optimal shim positions for each individual subject are computed from obtained field map using a convex optimization algorithm. Passive shim experiments at predetermined fixed shim positions vs. individually adjusted shim positions were performed and compared. The results show that intersubject variability exists in the optimal shim positions and that the location-sensitive method proposed can be useful for improving main field homogeneity in vivo.

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