A Novel Interleaved Spiral Imaging Motion Correction Technique Using Orbital Navigators

Spiral imaging is often performed for fast MRI data acquisition. It has been shown not to produce apparent artifacts related to flow in the reconstructed images. However, spiral imaging 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”. Since each navigator takes less than 1ms, the total scan time is almost identical to normal spiral imaging. When an object moves during data acquisition, it is difficult to create a frequency field map for off-resonance correction because there is motion-dependent misregistration between the two images acquired with different TE’s. However, in the newly proposed technique, this difficulty has been overcome by combining the motion correction method with the recently proposed off-resonance correction method using variable density spirals (ORC-VDS), thereby enabling both motion compensation and off resonance correction with no additional scanning.

Figure 1: A spiral k-space trajectory with an orbital navigator. The data along the orbital navigator is used to correct for both translational and rotational motion artifacts.

Figure 2: The image without correction (A), the image with correction (B), and the static image (C). Note that significant motion artifact reduction can be observed.