Dynamic scan-plane tracking using MR position monitoring

An MR-based method for tracking subject motion is presented. The technique identifies subject motion from the three-dimensional positions of three sma ll samples attached to the subject in a fixed, triangular configuration. Th e updated positions of these samples relative to their initial positions de termine a rigid body transformation. Applied to the MRI scan prescription v ia adaptive feedback controls, this transformation yields an updated MRI sc an plane that tracks the prescribed imaging section as the subject moves. T he scan-plane tracking procedure is demonstrated experimentally for two-dim ensional imaging of a standard imaging phantom and the head of a human subj ect. Sets of images were acquired sequentially, with motion (translations a nd/or rotations) introduced between image frames. The scan-plane tracking s ystem provides wall registered image slices of the same section, adaptively compensating for the subject motion.