New magnetic resonance tagging technique for directly measuring the strain tensor of the in vivo human heart

The authors introduce a new phase-based magnetic resonance (MR) tagging method for a direct and noninvasive measurement of the 2-D myocardial strain tensor. Their high-frequency complex sinusoidal tags can be conveniently generated with the SPAMM tagging pulse sequence, followed by one-sided band-pass imaging. In the authors´ method, the instantaneous spatial phase data of the deformed tags carry the essential information with regard to local myocardial activity from which the strain tensor can be computed directly. Segmentation of tags and/or epicardial and endocardial contours is not required. As a result, the authors´ proposed method is relatively simple to implement on current clinical MRI scanners, cheap in terms of computational cost, and can be generalized, at least conceptually, for 3-D imaging. The authors present computer simulation results for an idealized 2-D myocardial contraction to demonstrate the key idea as well as the performance of their method