Application of multi-shot EPI to mitigate image distortion in diffusion tensor imaging of the human lumbar spinal cord

The lumbar spinal cord is significantly understudied with quantitative MRI methods such as diffusion tensor imaging (DTI), in part due to challenges of spatial and temporally-varying field inhomogeneities that cause distortion in commonly used single-shot EPI sequences. In this pilot study, we implemented IRIS Zoom, a multi-shot, reduced field-of-view method that corrects for shot-to-shot variations, phase errors (2D navigation), and T2* dephasing. Multi-shot EPI was successfully acquired in healthy volunteers at 3T, led to reduced geometric distortions, and provided quantitative DTI values comparable to those derived from single-shot EPI. Multi-shot EPI is feasible for high-resolution DTI of the lumbar cord.