Torque-balanced gradient coils for magnetic resonance imaging

Details Torque-balanced gradient coils for magnetic resonance imaging Torque-balanced gradient coils for magnetic resonance imaging

1994-06-30

1996-12-03

O'Shea, Sandra L.

Electricity: measuring and testing

Particle precession resonance

Spectrometer components

324322, 1286532, 1286535, G01V 300, G01V 314, A61B 5055

Patent

active

055811850

ABSTRACT:
A magnetic resonance imaging apparatus includes main field coils (10) for generating a temporally uniform magnetic field longitudinally through a central bore (12). A whole body gradient magnetic field coil (30) and radio frequency coil (36) are disposed around the bore. An insertable coil assembly (40) includes an insertable gradient coil (42) and a radio frequency coil (44). The insertable coil assembly place the gradient and radio frequency coil significantly closer to the region of interest to be imaged than the whole body coils. In the embodiment of FIG. 2, the gradient coil assembly is a cylindrical coil assembly including x, y, and z-gradient coils which receive current pulses in order to generate linear, uniform, magnetic field gradients through a selected region adjacent a patient end of the gradient coil. Although the asymmetric coil design promotes linearity of the magnetic field gradients and improves patient access, the currents in the asymmetric coil interact with the main magnetic field to generate a net torque. Additional windings (72) are added on the service end, opposite to the patient end, of the gradient coil to (1) contribute to the linearity and uniformity of the gradient magnetic field and (2) to generate counteracting torques.

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"Torque Free Asymmetric Gradient Coils for Echo Planar Imaging", Abduljalil, et al., Mag. Res. in Med., 31 (1994) Apr. No. 4, pp. 450-453.
"Torque Compensated Asymmetric Gradient Coils for EPI", Abduljalil, et al., SMRM 12th Annual Meeting, vol. 3, p. 1306.
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