• David Atkinson, Serena Counsell, Joseph V Hajnal, Philip G Batchelor, Derek L G Hill, and David J Larkman.
• Centre for Medical Image Computing, University College London, United Kingdom. D.Atkinson@ucl.uk
• Magn Reson Med. 2006 Nov 1; 56 (5): 1135-9.

AbstractCardiac pulsatility causes a nonrigid motion of the brain. In multi-shot diffusion imaging this leads to spatially varying phase changes that must be corrected. A conjugate gradient based reconstruction is presented that includes phase changes measured using two-dimensional navigator echoes, coil sensitivity information, navigator-determined weightings, and data from multiple coils and averages.A multi-shot echo planar sequence was used to image brain regions where pulsatile motion is not uniform. Reduced susceptibility artifacts were observed compared to a clinical single-shot sequence. In a higher slice, fiber directions derived from single-shot data show distortions from anatomical scans by as much as 7 mm compared to less than 2 mm for our multi-shot reconstructions. The reduced distortions imply that phase encoding can be applied in the shorter left-right direction, enabling time savings through the use of a rectangular field of view. Higher resolution diffusion imaging in the spine permits visualization of a nerve root.(c) 2006 Wiley-Liss, Inc.

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