Self‐navigated interleaved spiral (SNAILS): Application to high‐resolution diffusion tensor imaging

Abstract A fat‐saturated twice‐refocused spin echo sequence was implemented on a GE Signa 1.5‐T whole‐body system for diffusion‐weighted imaging. Data were acquired using an analytically designed interleaved variable‐density (VD) spiral readout trajectory. This flexible design algorithm allowed real‐time prescription on the scanner. Each interleaf of the VD spiral oversampled the center of k ‐space. The oversampling provided an inherent motion compensation capability. The resultant diffusion‐weighted images showed good quality without any retrospective motion correction. An iterated motion correction algorithm was developed to further reduce the signal cancellation artifact caused by motion‐induced phase error. In this algorithm, a low‐resolution phase map was estimated using the oversampled data in the center of k ‐space in order to correct for phase error in image space. In vivo diffusion tensor imaging (DTI) studies were performed on the brains of healthy volunteers. High‐quality isotropic diffusion‐weighted images, trace maps, and FA maps from axial, sagittal, and coronal slices were obtained using a VD spiral readout trajectory with matrix size 256 × 256. To our knowledge, this was also the first time in vivo 512 × 512 DTI results were reported. Magn Reson Med 52:1388–1396, 2004. © 2004 Wiley‐Liss, Inc.