Multiple Sclerosis Research Today is a free monthly online journal that collates and summarizes the latest research about Multiple Sclerosis, including details on diagnosis, symptoms, treatment, prognosis.

Interscan registration using navigator echoes.

Welch EB, Manduca A, Grimm RC, Jack CR

Department of Diagnostic Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.

A common problem in clinical MRI is anatomic misalignment of imaging slices across successive examinations. This unnecessarily complicates the radiologic assessment of anatomic change over time on serial MRI studies. To address this problem, spherical navigator echoes, which can detect rigid body motion in all six degrees of freedom, were used to guide spatial location and orientation adjustments to an exam prescription to match the reference frame of images acquired in an earlier exam. An initial linear navigator echo is also necessary to effect coarse Z translation adjustments prior to fine six degrees of freedom adjustment with a spherical navigator echo. Results of this technique are presented for head image volumes of five volunteers. Each volunteer was imaged on two scanners. In all cases, the reference frame adjustments provided by the navigator echoes substantially improved the alignment of the latter exam and performed well compared to retrospective image-based registration.

Published 7 December 2004 in Magn Reson Med, 52(6): 1448-52.
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