Local planar gradients with order‐of‐magnitude strength and speed advantage

Autor: Christopher J. Hardy, Cornelius von Morze, Luca Marinelli, Bulent Aksel, Paul A. Bottomley, Bruce D. Collick
Rok vydání: 2007
Předmět:
Zdroj: Magnetic Resonance in Medicine. 58:134-143
ISSN: 1522-2594
0740-3194
DOI: 10.1002/mrm.21263
Popis: A three-axis uniplanar gradient coil was designed and built to provide order-of-magnitude increases in gradient strength of up to 500 mT/m on the x- and y-axes, and 1000 mT/m for the z-axis at 640 A input over a limited FOV ( approximately 16 cm) for superficial regions, compared to conventional gradient coils, with significant gradient strengths extending deeper into the body. The gradient set is practically accommodated in the bore of a conventional whole-body, cylindrical-geometry MRI scanner, and operated using standard gradient supplies. The design was optimized for gradient linearity over a restricted volume while accounting for the practical problems of torque and heating. Tests at 320 A demonstrated up to 420-mT/m gradients near the surface at efficiencies of up to 1.4 mT/m/A. A new true 2D gradient-nonlinearity correction algorithm was developed to rectify gradient nonlinearities and considerably expand the imageable volumes. The gradient system and correction algorithm were implemented in a standard 1.5 T scanner and demonstrated by high-resolution imaging of phantoms and humans.
Databáze: OpenAIRE
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