Three‐dimensional, in vivo MRI with self‐gating and image coregistration in the mouse

Motion during magnetic resonance imaging (MRI) scans routinely results in undesirable image artifact or blurring. Since high‐resolution, three‐dimensional (3D) imaging of the mouse requires long scan times for satisfactory signal‐to‐noise ratio (SNR) and image quality, motion‐related artifacts are likely over much of the body and limit applications of mouse MRI. In this investigation, we explored the use of self‐gated imaging methods and image coregistration for improving image quality in the presence of motion. Self‐gated signal results from a modified 3D gradient‐echo sequence showed detection of periodic respiratory and cardiac motion in the adult mouse—with excellent comparison to traditional measurements, sensitivity to respiration‐induced tissue changes in the brain, and even detection of embryonic cardiac motion in utero. Serial image coregistration with rapidly‐acquired, low‐SNR volumes further enabled detection and correction of bulk changes in embryo location during in utero imaging sessions and subsequent reconstruction of high‐quality images. These methods, in combination, are shown to expand the range of applications for 3D mouse MRI, enabling late‐stage embryonic heart imaging and introducing the possibility of longitudinal developmental studies from embryonic stages through adulthood. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.