Prospective motion correction for and susceptibility mapping using spherical navigators

To perform prospective motion correction (PMC) for improved $$ and susceptibility mapping using a purely navigator-based approach.

Spherical navigators (SNAVs) were combined with an additional FID readout for simultaneous measurement of motion and zeroth-order field shifts. The resulting FIDSNAVs were interleaved for PMC of a multi-echo gradient echo sequence with retrospective $$ correction. Experiments were performed on a 3T scanner with a 32-channel head coil. Performance was assessed in five volunteers with motion prompts derived from real unintentional motion trajectories.

At short TEs, PMC alone was sufficient to achieve good image quality; at longer TEs, retrospective $$ correction was often just as important for artifact reduction as motion correction. Both PMC and retrospective $$ correction reduced error in $$ and susceptibility maps for all participants. Residual artifacts were observed in the most severe motion case.

Combining SNAVs with an additional FID readout enables simultaneous motion and field correction with no additional hardware requirements, improving the fidelity of quantitative mapping in the presence of motion.