EPI image based long term eddy current pre-emphasis calibration
US6127826A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 27, 1999 |
| Grant date | Oct 3, 2000 |
| Priority date | — |
| Expiry date | Jan 27, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/5616
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of calibrating pre-emphasis gradient pulse conditioning for long term eddy current compensation in an MRI system is provided. It includes positioning an object in the MRI system for imaging therewith. A long term eddy current generating pre-scan gradient pulse is applied, and after a delay, an EPI sequence is run such that a resulting image of the object is acquired. This process of applying the pre-scan gradient pulse followed by the EPI sequence is repeated while varying the delay therebetween. Size variations in the resulting images of the object are observed, and these size variations are fit to an exponential curve to obtain one or more time constants for the long term eddy currents. Next, a reference EPI sequence is run without applying the long term eddy current generating pre-scan gradient pulse such that a reference image of the object is acquired. The long term eddy current generating pre-scan gradient pulse is reintroduced, and after a delay which is shorter than the time constants, a test EPI sequence is run such that a test image of the object is acquired. The process of applying the pre-scan gradient pulse followed by the test EPI sequence is repeated while a…
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