Harmonic Phase Flow for Tissue Motion Estimation in Tagged MR Sequences

In this work, we present a fully auto- mated method for tissue deformation estimation in tagged magnetic resonance images (TMRI). The method consists of two main stages: in the first one, we use Gabor filter banks, tuned indepen- dently for each left ventricle level, that allows to obtain optimally filtered complex images the phase of which is a property that remains constant along the cardiac cycle. This fact can be thought as the brightness constancy condition required by clas- sical optical flow (OF) methods. Pairs of these filtered sequences, together to a variational for- mulation are used in a second step with obtain dense continuous deformation map that we call Harmonic Phase Flow. This method has been used to determine reference values of ventricular torsion (VT) in a set of 8 healthy volunteers. The results encourage the use of VT as a useful parameter for ventricular func- tion assessment in clinical routine.