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Perturbation method for magnetic field calculations of nonconductive objects
Author(s) -
Jenkinson Mark,
Wilson James L.,
Jezzard Peter
Publication year - 2004
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.20194
Subject(s) - voxel , perturbation (astronomy) , magnetic field , convolution (computer science) , orientation (vector space) , computer science , distortion (music) , basis (linear algebra) , physics , nuclear magnetic resonance , algorithm , mathematics , computer vision , artificial intelligence , geometry , artificial neural network , quantum mechanics , amplifier , computer network , bandwidth (computing)
Inhomogeneous magnetic fields produce artifacts in MR images including signal dropout and spatial distortion. A novel perturbative method for calculating the magnetic field to first order (error is second order) within and around nonconducting objects is presented. The perturbation parameter is the susceptibility difference between the object and its surroundings (for example, ∼10 ppm in the case of brain tissue and air). This method is advantageous as it is sufficiently accurate for most purposes, can be implemented as a simple convolution with a voxel‐based object model, and is linear. Furthermore, the method is simple to use and can quickly calculate the field for any orientation of an object using a set of precalculated basis images. Magn Reson Med 52:471–477, 2004. © 2004 Wiley‐Liss, Inc.