TY - JOUR
T1 - Local planar gradients with order-of-magnitude strength and speed advantage
AU - Aksel, Bulent
AU - Marinelli, Luca
AU - Collick, Bruce D.
AU - Von Morze, Cornelius
AU - Bottomley, Paul A.
AU - Hardy, Christopher J.
PY - 2007/7
Y1 - 2007/7
N2 - 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 (∼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 1.5T scanner and demonstrated by high-resolution imaging of phantoms and humans.
AB - 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 (∼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 1.5T scanner and demonstrated by high-resolution imaging of phantoms and humans.
KW - Gradient nonlinearity
KW - High-speed gradients
KW - Local gradients
KW - Peripheral nerve stimulation
KW - Planar gradients
UR - http://www.scopus.com/inward/record.url?scp=34547785704&partnerID=8YFLogxK
U2 - 10.1002/mrm.21263
DO - 10.1002/mrm.21263
M3 - Article
C2 - 17659620
AN - SCOPUS:34547785704
SN - 0740-3194
VL - 58
SP - 134
EP - 143
JO - Magnetic resonance in medicine
JF - Magnetic resonance in medicine
IS - 1
ER -