Patent ID: 6127826
Filing Date: 2000-10-03
Classification: G01R

Abstract:
A method of calibrating pre-emphasis gradient pulse conditioning for long term eddy current compensation in an MRI system comprising:(a) positioning an object in the MRI system for imaging therewith;(b) applying a long term eddy current generating pre-scan gradient pulse;(c) after a delay, running an EPI sequence and acquiring a resulting image of the object;(d) repeating steps b and c while varying the delay;(e) observing size variations in the resulting images of the object;(f) fitting the size variations to an exponential curve to obtain one or more time constants for the long term eddy currents;(g) running a reference EPI sequence without applying the long term eddy current generating pre-scan gradient pulse such that a reference image of the object is acquired;(h) applying the long term eddy current generating pre-scan gradient pulse;(i) after a delay which is shorter than the time constants, running a test EPI sequence and acquiring a test image of the object; and,(j) repeating steps h and i while adjusting the pre-emphasis gradient pulse conditioning which is based upon the time constants obtained until the test images of the object have a size substantially equivalent to that of the reference image.