Out‐and‐in spiral spectroscopic imaging in rat brain at 7 T

With standard spectroscopic imaging, high spatial resolution is achieved at the price of a large number of phase‐encoding steps, leading to long acquisition times. Fast spatial encoding methods reduce the minimum total acquisition time. In this article, a k ‐space scanning scheme using a continuous series of growing and shrinking, or “out‐and‐in,” spiral trajectories is implemented and the feasibility of spiral spectroscopic imaging for animal models at high B 0 field is demonstrated. This method was applied to rat brain at 7 T. With a voxel size of about 8.7 μl (as calculated from the point‐spread function), a 30 × 30 matrix, and a spectral bandwidth of 11 kHz, the minimum scan time was 9 min 20 sec for a signal‐to‐noise ratio of 7.1 measured on the N‐acetylaspartate peak. Magn Reson Med 50:1127–1133, 2003. © 2003 Wiley‐Liss, Inc.