Integration of an external motion tracking system with the MR scanner for highly accurate real-time prospective motion correction

Image quality in MRI may be critically disturbed by subject motion. A number of MR-based approaches, such that orbital(1) or spherical(2) navigators, has been developed to reduce the motion sensitivity of the standard 2D and 3D imaging techniques. Navigators, however, are not compatible with every imaging method because of possible steady state perturbations and measurement time considerations. Employing external motion tracking hardware for motion correction in MRI(3-7) is a promising approach. However, up to now it failed to meet the requirements on both the accuracy placed by high resolution imaging and the overall system latency to enable prospective corrections. The goal of this work was to seamlessly integrate a high-end motion tracking system with the MR scanner and to optimise its accuracy by the development of a novel cross-calibration method. In addition, a method to determine experimentally the total latency of the measurement system is proposed.