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Requirements for room temperature shimming of the human brain

✍ Scribed by Stuart Clare; John Evans; Peter Jezzard

Publisher: John Wiley and Sons
Year: 2005
Tongue: English
Weight: 132 KB
Volume: 55
Category: Article
ISSN: 0740-3194
DOI: 10.1002/mrm.20735

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✦ Synopsis

Abstract

Room temperature (RT) shims are used routinely in MRI to remove global and local B~0~ field inhomogeneity introduced by the subject. Most clinical scanners use only second‐order spherical harmonic terms, but with the increasing availability of very high field systems, third‐ and fourth‐order terms are a serious consideration. However, choosing appropriate coil strengths is of critical importance in shim coil design since overspecification of the shim strengths can lead to a variety of problems, including shim coil self‐resonance. In this study B~0~ field map data collected over a period of 6 months (over 400 brain volumes) were analyzed to find the characteristic B‐fields required to shim these brains. These data can be used to specify the coil requirements to effectively shim the human brain. Magn Reson Med, 2006. © 2005 Wiley‐Liss, Inc.

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