Atkinson, D; Counsell, S; Hajnal, JV; Batchelor, PG; Hill, DLG; Larkman, DJ; (2006) Nonlinear phase correction of navigated multi-coil diffusion images. MAGN RESON MED , 56 (5) 1135 - 1139. 10.1002/mrm.21046.
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Cardiac 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 singleshot 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.
|Title:||Nonlinear phase correction of navigated multi-coil diffusion images|
|Keywords:||conjugate gradient, diffusion MRI, motion correction, 2D navigator, MOTION, ARTIFACTS, BRAIN, RECONSTRUCTION, ECHOES, SENSE|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Medical Sciences > Medicine (Division of)|
UCL > School of BEAMS > Faculty of Engineering Science > Medical Physics and Bioengineering
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