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Requirements for room temperature shimming of the human brain
Author(s) -
Clare Stuart,
Evans John,
Jezzard Peter
Publication year - 2006
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.20735
Subject(s) - shim (computing) , electromagnetic coil , computer science , nuclear magnetic resonance , acoustics , physics , medicine , surgery , erectile dysfunction , quantum mechanics
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.