Magnetic field homogenization of the human prefrontal cortex with a set of localized electrical coils.

Juchem, Christoph; Nixon, Terence W.; McIntyre, Scott; Rothman, Douglas L.; de Graaf, Robin A.

The prefrontal cortex is a common target brain structure in psychiatry and neuroscience due to its role in working memory and cognitive control. Large differences in magnetic susceptibility between the air-filled sinuses and the tissue/bone in the frontal part of the human head cause a strong and highly localized magnetic field focus in the prefrontal cortex. As a result, image distortion and signal dropout are observed in MR imaging. A set of external electrical coils is presented that provides localized and high-amplitude shim fields in the prefrontal cortex, with minimum impact on the rest of the brain when combined with regular zero- to second-order spherical harmonics shimming. The experimental realization of the new shim method strongly minimized or even eliminated signal dropout in gradient-echo images acquired at settings typically used in functional magnetic resonance at 4 T. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc.

Magnetic Resonance in Medicine, 2010, Vol 63, Issue 1, p171

0740-3194

Academic Journal

10.1002/mrm.22164