Gradient and shim technologies for ultra high field MRI.

Publication Type	Review
Authors	Winkler S, Schmitt F, Landes H, de Bever J, Wade T, Alejski A, Rutt B
Journal	Neuroimage
Volume	168
Pagination	59-70
Date Published	11/30/2016
ISSN	1095-9572
Keywords	Brain, Magnetic Fields, Magnetic Resonance Imaging
Abstract	Ultra High Field (UHF) MRI requires improved gradient and shim performance to fully realize the promised gains (SNR as well as spatial, spectral, diffusion resolution) that higher main magnetic fields offer. Both the more challenging UHF environment by itself, as well as the higher currents used in high performance coils, require a deeper understanding combined with sophisticated engineering modeling and construction, to optimize gradient and shim hardware for safe operation and for highest image quality. This review summarizes the basics of gradient and shim technologies, and outlines a number of UHF-related challenges and solutions. In particular, Lorentz forces, vibroacoustics, eddy currents, and peripheral nerve stimulation are discussed. Several promising UHF-relevant gradient concepts are described, including insertable gradient coils aimed at higher performance neuroimaging.
DOI	10.1016/j.neuroimage.2016.11.033
PubMed ID	27915120
PubMed Central ID	PMC5591082