期刊
MAGNETIC RESONANCE IN MEDICINE
卷 66, 期 2, 页码 314-323出版社
WILEY
DOI: 10.1002/mrm.22805
关键词
single voxel spectroscopy; motion correction; shim correction; navigator
资金
- South African Research Chairs Initiative of the Department of Science and Technology
- National Research Foundation of South Africa
- University of Cape Town
- Medical Research Council of South Africa
- Ellison Medical Foundation
- NIH [R21AA017410, R33DA026104, R21EB008547, R01NS055754, P41RR014075]
In population groups where head pose cannot be assumed to be constant during a magnetic resonance spectroscopy examination or in difficult-to-shim regions of the brain, real-time volume of interest, frequency, and shim optimization may be necessary. We investigate the effect of pose change on the B-0 homogeneity of a (2 cm)(3) volume and observe typical first-order shim changes of 1 mu T/m per 1 degrees rotation (chin down to up) in four different volumes of interest in a single volunteer. An echo planar imaging volume navigator was constructed to measure and apply in real-time within each pulse repetition time: volume of interest positioning, frequency adjustment, and first-order shim adjustment. This volume navigator is demonstrated in six healthy volunteers and achieved a mean linewidth of 4.4 Hz, similar to that obtained by manual shim adjustment of 4.9 Hz. Furthermore, this linewidth is maintained by the volume navigator at 4.9 Hz in the presence of pose change. By comparison, a mean linewidth of 7.5 Hz was observed, when no correction was applied. Magn Reson Med 66:314-323,2011. (C)2011 Wiley-Liss, Inc.
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