Pseudolesions arising from unfolding artifacts in diffusion imaging with use of parallel acquisition: origin and remedies.

Diffusion imaging acquired with echo-planar imaging (EPI) is usually performed with parallel imaging to reduce geometric distortions, especially at high fields. This study reports the occurrence of pseudolesions in EPI with parallel imaging. The unfolding artifacts are attributed as arising from a mismatch between RF sensitivity profiles and distorted acquisition data in the presence of susceptibility effects, plus strong signals on the b=0 images. Examples of pseudolesions from the eyeballs are shown, and remedies are suggested.