Real-time correction of rigid motion and 1 st -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 1 st 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.