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Optimization of torque‐balanced asymmetric head gradient coils
Author(s) -
Alsop David C.,
Connick Thomas J.
Publication year - 1996
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.1910350614
Subject(s) - torque , electromagnetic coil , head (geology) , nuclear magnetic resonance , inductance , scanner , acoustics , physics , homogeneity (statistics) , excitation , control theory (sociology) , materials science , mechanics , computer science , optics , voltage , machine learning , control (management) , quantum mechanics , geomorphology , artificial intelligence , thermodynamics , geology
Abstract Local gradient coils can improve the performance of echo‐planar, diffusion, and short TE imaging in the brain. A modified singular value decomposition algorithm, which allows the rapid optimization and comparison of designs, was employed to optimize head size gradient coils. A theoretical expression for the torque on a cylindrical coil is presented and used to design coils that are free from torque while pulsed within a magnetic field. Gradient coils of various lengths both with and without torque constraints were compared; although torque‐free coils do not perform as well as unbalanced coils, asymmetric torque‐balanced coils can achieve comparable homogeneity with only a modest Increase in inductance and resistance. Both types of coils outperform body size gradient coils by a dramatic margin. A three‐axis head gradient designed using these techniques was constructed and used for brain imaging on a clinical scanner.