Three dimensional shape, deformation and motion analysis of mitral annuli using transesophageal echocardiographic data

Deformation and motion of the Mitral Annulus (MA) is closely related to the left ventricular function. Measurement and visualization of the characteristic parameters in 3D will help in understanding the relationship. Data for this study was acquired from patients undergoing transesophageal echocardiographic examination with the transducer aligned along the axis roughly perpendicular to the annuli, and rotated automatically to cover 360 degrees. ECG gated images were acquired at 24 angles for each phase of the cardiac cycle. The annuli hinge points were identified from each echo image and the annuli reconstructed. The parameters measured to characterize the annuli were: i) area of projection, ii) non-planarity, iii) excursion of annulus centroid, iv) change in the annulus orientation. We validated the method using a wire loop shaped in the form of a saddle and a planar rubber ring imaged in a water bath at different orientations. Four MAs were reconstructed using this method. Two were patients with dilated cardiomyopathy (DCM) and two were patients with normal ventricular function. The change in parameters was measured from systole to diastole. Percentage change in area (29% vs. 16%) and excursion (8 mm vs. 3 mm) were much larger for normals than for patients. While, changes in non-planarity (20%) and orientation (6deg) were similar. These preliminary results show that MA parameters do reflect the abnormality, and could be used for diagnosis and prognosis of patients with bad ventricles.