b-Matrix Correction Applied to High Resolution DTI

INTRODUCTION – High resolution Diffusion Tensor Imaging (DTI) has been challenging for several reasons. Perhaps the major obstacle is due to the random phase effects that change between successive shots and pixel-by-pixel misregistration caused by patient motion. In addition, DTI images acquired with EPI are typically hampered by geometric distortion, blurring, and – in the case of multi-shot EPI – suffer from aliasing artifacts in the presence of motion. Short Axis readout PROPELLER-EPI (SAP-EPI) has been very effective in reducing distortion and motion artifacts in high resolution DTI while keeping the scan time within reasonable limits [1]. One shortcoming of SAP-EPI is that it cannot correct for the alterations in the diffusion encoding direction (i.e., the b-matrix) due to gross subject motion. In this study, we combined SAP-EPI [1] with the single-step non-linear diffusion tensor estimation [2] to perform b-matrix correction for SAP-EPI and achieve highresolution motion corrected DTI datasets.