HARP tracking using locally-uniform deformation assumption

Background Tracking of the myocardium points in tagged MRI images using the Harmonic Phase (HARP) method is widely used to estimate the myocardium regional function. Nevertheless, mistracking might occur in HARP due to errors in selecting the phase extraction filter or due to violation of phase-constancy near the myocardium edges [1]. In this work, we add a constraint that within any small neighborhood the myocardium deformation is uniform which allows using common methods of optical flow tracking such as the Lucas-Kanade algorithm [2]. We show that this assumption significantly improves the reliability of the HARP tracking especially at the borders of the myocardium.