Magnetic resonance imaging method and apparatus employing eddy c

Details Magnetic resonance imaging method and apparatus employing eddy c Magnetic resonance imaging method and apparatus employing eddy c

1993-06-29

1995-09-12

O'Shea, Sandra L.

Electricity: measuring and testing

Particle precession resonance

Using a nuclear resonance spectrometer system

G01R 3348

Patent

active

054500109

ABSTRACT:
In an MRI device (1) operating according to a spin-echo method, switched gradient magnetic fields are applied in the form of slice selection (231-233), phase encoding (243-243, 243'243') and read gradients (252-253). The switching of the gradients causes eddy currents in metal parts of the apparatus. The eddy currents disturb the applied magnetic fields, thereby changing the phases of the precessing nuclear spins of a body (7) to be examined and causing artefacts in a reconstructed image. Another source of disturbance may be phase-distortion in the RF amplifier. By modifying a gradient (251, 231') in between the excitation pulse (221) and the first refocusing pulse to (222) in the spin-echo sequence and/or a change in phase of the RF-pulses, the effects of the disturbances can largely be compensated for. The additional gradient size is adjusted by measuring the position in time and the relative phase of spin-echo signals (162, 163) in a preparatory sequence (121-173).

REFERENCES:
patent: 4647858 (1987-03-01), Bottomley
patent: 4649345 (1987-03-01), Yoda et al.
patent: 4684891 (1987-08-01), Feinberg
patent: 4694250 (1987-09-01), Iwasaka et al.
patent: 4724388 (1988-02-01), Sano et al.
patent: 4859946 (1989-08-01), Kuhara
patent: 4893081 (1990-01-01), Zur
patent: 4896112 (1990-01-01), Ratzel et al.

Affiliated with

Also associated with

Rating

Magnetic resonance imaging method and apparatus employing eddy c does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Magnetic resonance imaging method and apparatus employing eddy c, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic resonance imaging method and apparatus employing eddy c will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-407790