Multiple gradient echo sequence optimized for rapid, single-scan mapping of R at high B0
✍ Scribed by Jim M. Wild; W.R. Wayne Martin; Peter S. Allen
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 510 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0740-3194
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✦ Synopsis
Abstract
A multiple‐gradient‐echo sequence is proposed for accurately mapping R in the presence of in‐slice macroscopic susceptibility gradients. In‐slice signal loss caused by background macroscopic susceptibility gradients is mitigated by combining three successive gradient‐echo images whose slice refocus gradients are successively incremented. The optimum incrementation of slice‐refocusing gradients was determined by numerical simulation. By repeating further cycles of three images in the same sequence, artifact‐compensated data spanning a range of echo times (TEs) was acquired leading to single‐scan, R maps that are quantitatively reflective of microscopic field inhomogeneities. The performance of the sequence was demonstrated at 3.0T, first with a doped aqueous phantom, and then on the head of a normal volunteer. That performance is compared quantitatively with previously published work. Magn Reson Med 48:867–876, 2002. © 2002 Wiley‐Liss, Inc.