Accelerated short-TE 3D proton echo-planar spectroscopic imaging using 2D-SENSE with a 32-channel array coil
✍ Scribed by Ricardo Otazo; Shang-Yueh Tsai; Fa-Hsuan Lin; Stefan Posse
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 796 KB
- Volume
- 58
- Category
- Article
- ISSN
- 0740-3194
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✦ Synopsis
Abstract
MR spectroscopic imaging (MRSI) with whole brain coverage in clinically feasible acquisition times still remains a major challenge. A combination of MRSI with parallel imaging has shown promise to reduce the long encoding times and 2D acceleration with a large array coil is expected to provide high acceleration capability. In this work a very high‐speed method for 3D‐MRSI based on the combination of proton echo planar spectroscopic imaging (PEPSI) with regularized 2D‐SENSE reconstruction is developed. Regularization was performed by constraining the singular value decomposition of the encoding matrix to reduce the effect of low‐value and overlapped coil sensitivities. The effects of spectral heterogeneity and discontinuities in coil sensitivity across the spectroscopic voxels were minimized by unaliasing the point spread function. As a result the contamination from extracranial lipids was reduced 1.6‐fold on average compared to standard SENSE. We show that the acquisition of short‐TE (15 ms) 3D‐PEPSI at 3 T with a 32 × 32 × 8 spatial matrix using a 32‐channel array coil can be accelerated 8‐fold (R = 4 × 2) along y‐z to achieve a minimum acquisition time of 1 min. Maps of the concentrations of N‐acetyl‐aspartate, creatine, choline, and glutamate were obtained with moderate reduction in spatial‐spectral quality. The short acquisition time makes the method suitable for volumetric metabolite mapping in clinical studies. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.