Local planar gradients with order-of-magnitude strength and speed advantage.
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.
Aksel
Bulent
B
GE Global Research, Niskayuna, New York, USA.
Marinelli
Luca
L
GE Global Research, Niskayuna, New York, USA.
Collick
Bruce D
BD
GE Healthcare, Waukesha, Wisconsin, USA.
Von Morze
Cornelius
C
UCSF/UCB Joint Graduate Group in Bioengineering, University of California-San Francisco, San Francisco, California, USA.
Bottomley
Paul A
PA
Johns Hopkins University Department of Radiology, Baltimore, Maryland, USA.
Hardy
Christopher J
CJ
GE Global Research, Niskayuna, New York, USA.
D000465:Algorithms; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging