3D diffusion tensor imaging with 2D navigated turbo spin echo.
A Cartesian two-dimensional navigator with variable orientation for online motion correction is introduced. It corrects for all possible zeroth- and first-order phase errors due to rigid-body motion of a subject during the diffusion-weighting preparation. The technique is developed for the application of three-dimensional (3D) imaging sequences, which offer the opportunity of high-resolution diffusion-weighted imaging, or diffusion tensor imaging (DTI) with isotropic voxel resolution. The navigator was applied to a displaced 3D turbo spin-echo sequence with an ECG-gated diffusion preparation to avoid phase errors due to gross brain pulsation. Online and offline corrected in vivo images acquired with this sequence are compared to investigate the advantages of online correction. Also eigenvector maps of the diffusion tensor are presented with an isotropic resolution of 1 mm3, which indicate that this new navigator technique is a promising approach for high-resolution DTI.