Real time constrained motion estimation for ECG-gated cardiac MRI

Continuous magnetic resonance (MR) imaging is a promising tool for image-guided cardiac interventions. However, cardiac imaging is complicated by both, cardiac and respiratory motion. While the former is commonly addressed by cardiac gating, the latter requires a real time motion compensation. Here, a new image based motion estimation is proposed, extending the initial Horn & Schunck optical flow approach by an additional regularization term. This term allows to integrate displacement of physiological landmarks, which are obtained in a preparation step using pattern matching. The proposed method was evaluated on the left ventricle (LV) of cardiac MR-images and showed a better estimation accuracy compared to the original Horn & Schunck approach.