Real-time correction of rigid motion and 1st-order shims using rapid 3D orbital navigators

Rigid head motion, which is a challenging problem in itself, is further accompanied by field variations as the object moves in an inhomogeneous background field, and because pose changes lead to varying susceptibility-induced fields. In contrast to external sensors like optical cameras, navigators are naturally sensitive to field variations. We propose a fast, scan-integrated calibration method to sensitize the 3D orbital navigators to rigid motion and 1st order shim fields. The obtained motion and field parameters are used to correct the scan geometry and shim settings in real-time. The performance is evaluated in phantom and in-vivo studies.