Enhanced 3D Myocardial Strain Estimation from Multi-View 2D CMR Imaging
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In this paper, we propose an enhanced 3D myocardial strain estimation procedure, which combines complementary displacement information from multiple orientations of a single imaging modality (untagged CMR SSFP images). To estimate myocardial strain across the left ventricle, we register the sets of short-axis, four-chamber and two-chamber views via a 2D non-rigid registration algorithm implemented in a commercial software (Segment, Medviso). We then create a series of interpolating functions for the three orthogonal directions of motion and use them to deform a tetrahedral mesh representation of a patient-specific left ventricle. Additionally, we correct for overestimation of displacement by introducing a weighting scheme that is based on displacement along the long axis. The procedure was evaluated on the STACOM 2011 dataset containing CMR SSFP images for 16 healthy volunteers. We show increased accuracy in estimating the three strain components (radial, circumferential, longitudinal) compared to reported results in the challenge, for the imaging modality of interest (SSFP). Our peak strain estimates are also significantly closer to reported measurements from studies of a larger cohort in the literature and our own ground truth measurements using Segment Strain Analysis Module. Our proposed procedure provides a relatively fast and simple method to improve 2D tracking results, with the added flexibility in either deforming a reconstructed mesh model from other image modalities or using the built-in CMR mesh reconstruction procedure. Our, proposed scheme presents a deforming patient-specific model of the left ventricle, using the commonest imaging modality , routinely administered in clinical settings, without requiring additional or specialized imaging protocols.
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