Combined Prospective Rigid-Body Motion Correction with Retrospective Non-Rigid Distortion Correction for EPI

Melvyn B. Ooi¹, Roland Bammer¹, Truman R. Brown²

Despite rigid-body realignment to compensate for head motion during an EPI time-series scan, non-rigid-body image deformations remain due to changes in the effective shim within the brain as the head moves through the B0 field. The current work presents a combined prospective + retrospective motion correction solution. Prospective rigid-body correction, where the scan-plane orientation is dynamically updated to track with the subject's head, is performed using an active marker setup. A retrospective distortion correction algorithm that uses the complex EPI-data is then applied to unwarp the remaining non-rigid image deformations caused by motion-induced shim changes.