Novel interleaved spiral imaging motion correction technique using orbital navigators.

Although spiral imaging seldom produces apparent artifacts related to flow, it remains sensitive to rapid object motion. In this article, a new correction method is presented for rapid rigid body motion in interleaved spiral imaging. With this technique, an identical circular navigator k-space trajectory is linked to each spiral trajectory. Data inconsistency due to both rotation and translation among spiral interleaves can be corrected by evaluating the magnitudes and phases of the data contained in the navigator "ring." Further, it is difficult to create a frequency field map for off-resonance correction when an object moves during a scan, because there is motion-dependent misregistration between the two images acquired with different TEs. However, this difficulty can be overcome by combining the motion-correction method with a recently proposed technique (off-resonance correction using variable-density spirals (ORC-VDS)), thereby enabling both motion compensation and off-resonance correction with no additional scanning.