Prospective Head Motion Correction in T1- and T2-Weighted Long Echo Train Sequences Using Servo Navigation.

PURPOSE: To integrate MR-based servo navigation in MPRAGE and 3D-TSE sequences and demonstrate its potential for prospective head motion correction in structural imaging.

METHODS

Repeated modules of servo navigators were inserted before each preparation pulse of MPRAGE and 3D-TSE sequences (before-prep) for rapid convergence of motion parameter estimation. Additionally, reference navigators were distributed along the imaging echo train to test a within-echo train correction (within-ET) with contrast-matched models, enabling more frequent geometry updates. The methods were evaluated in instructed motion experiments and in high-resolution scans at 7T.

RESULTS

Artifacts caused by instructed abrupt motion were clearly reduced in scans with servo navigation for both sequences using the before-prep correction. Residual artifacts of rapid in-train motion were further mitigated by the within-ET correction in MPRAGE. In high-resolution scans with minimal motion, servo navigation preserved fine anatomical details, while it improved image quality under involuntary motion in long acquisitions.

CONCLUSION

Servo navigation provides accurate real-time head motion correction for structural brain imaging.