Diffusion MRI acquisition and reconstruction

Abstract Single-shot EPI (SS-EPI) has been the primary imaging sequence used for diffusion-weighted imaging (DWI) due to its short scan time and insensitivity to motion. However, the SS-EPI technique usually suffers from geometric distortions, especially close to tissue boundaries with different magnetic susceptibilities. Moreover, SS-EPI is prone to blurring artifacts due to signal decay and has low spatial resolution. In this chapter, we will first introduce multi-shot EPI-based techniques to improve spatial resolution and reduce geometric distortions. Among them, point-spread-function-encoded EPI with parallel imaging acceleration can produce distortion-free diffusion images in an efficient way. Then, basic 3D diffusion imaging for isotropic high-resolution DWI will be explained. Finally, some non-EPI-based DWI techniques will be covered. New concepts of parallel imaging for diffusion imaging reconstruction will be explained.