Manifold learning characterization of abnormal myocardial motion patterns: application to CRT-induced changes

International audienceThe present paper aims at quantifying the evolution of a given motion pattern under cardiac resynchronization therapy (CRT). It builds upon techniques for population-based cardiac motion quantifica-tion (statistical atlases, for inter-sequence spatiotemporal alignment and the definition of normal/abnormal motion). Manifold learning is used on spatiotemporal maps of myocardial motion abnormalities to represent a given abnormal pattern and to compare any individual to that pattern. The methodology was applied to 2D echocardiographic sequences in a 4-chamber view from 108 subjects (21 healthy volunteers and 87 CRT candidates) at baseline, with pacing ON, and at 12 months follow-up. Experiments confirmed that recovery of a normal motion pattern is a necessary but not su cient condition for CRT response

A spatiotemporal statistical atlas of motion for the quantification of abnormal myocardial tissue velocities

International audienceIn this paper, we present a new method for the automatic comparison of myocardial motion patterns and the characterization of their degree of abnormality, based on a statistical atlas of motion built from a reference healthy population. Our main contribution is the computation of atlas-based indexes that quantify the abnormality in the motion of a given subject against a reference population, at every location in time and space. The critical computational cost inherent to the construction of an atlas is highly reduced by the definition of myocardial velocities under a small displacements hypothesis. The indexes we propose are of notable interest for the assessment of anomalies in cardiac mobility and synchronicity when applied, for instance, to candidate selection for cardiac resynchronization therapy (CRT). We built an atlas of normality using 2D ultrasound cardiac sequences from 21 healthy volunteers, to which we compared 14 CRT patients with left ventricular dyssynchrony (LVDYS). We illustrate the potential of our approach in characterizing septal flash, a specific motion pattern related to LVDYS and recently introduced as a very good predictor of response to CRT

Atlas-Based Quantification of Myocardial Motion Abnormalities: Added-Value for Understanding the Effect of Cardiac Resynchronization Therapy

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Temporal Diffeomorphic Free-Form Deformation for Strain Quantification in 3D-US Images

International audienceThis paper presents a new diffeomorphic temporal registration algorithm and its application to motion and strain quantification from a temporal sequence of 3D images. The displacement field is computed by forward eulerian integration of a non-stationary velocity field. The originality of our approach resides in enforcing time consistency by representing the velocity field as a sum of continuous spatiotemporal B-Spline kernels. The accuracy of the developed diffeomorphic technique was first compared to a simple pairwise strategy on synthetic US images with known ground truth motion and with several noise levels, being the proposed algorithm more robust to noise than the pairwise case. Our algorithm was then applied to a database of cardiac 3D+t Ultrasound (US) images of the left ventricle acquired from height healthy volunteers and three Cardiac Resynchronization Therapy (CRT) patients. On healthy cases, the measured regional strain curves provided uniform strain patterns over all myocardial segments in accordance with clinical literature. On CRT patients, the obtained normalization of the strain pattern after CRT agreed with clinical outcome for the three cases

Atlas-based Quantification of Myocardial Motion Abnormalities: Added-value for the Understanding of CRT Outcome?

International audienceIn this paper, we present the use of atlas-based indexes of abnormality for the quantification of cardiac resynchronization therapy (CRT) outcome in terms of motion. We build an atlas of normal motion from 21 healthy volunteers to which we compare 88 CRT candidates before and after the therapy. Abnormal motion is quantified locally in time and space using a statistical distance to normality, and changes induced by the therapy are related with clinical measurements of CRT outcome. Results correlate with recent clinical hypothesis about CRT response, namely that the correction of specific mechanisms responsible for cardiac dyssynchrony conditions the response to the therapy

Development of a Swine Model of Left Bundle Branch Block for Experimental Studies of Cardiac Resynchronization Therapy

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Inter-operator variability of shapes and strain patterns: insights from a myocardial strain course

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