Reconstruction of 3D dense cardiac motion from tagged MR sequences

This paper develops an energy minimization algorithm to reconstruct the 3D motion of transplanted hearts of small animals (rats) from tagged magnetic resonance (MR) sequences. We describe the heart by a layered aggregate of thin oriented elastic fibers. We use the orientation of myocardial fibers to develop a local dense motion of the heart. This dense model is fit to the tagged MRI data by minimizing an energy functional with two terms: the first term is the external energy, derived from matching the image intensities on the fibers across two consecutive frames; the second term is the fibers´ internal energy, derived from biomechanics analysis. This paper illustrates the application of the approach to a set of cardiac MR sequences containing four slices of a transplanted rat heart.