Quantitative analysis of the Mobility of the left Ventricle using a Dynamic 3 D Model
Résumé
This paper presents a method for the quantitative analysis of the mobility of the left ventricle (LV), based on the development of a dynamic 3-D deformable model. The model consists of a superquadric with various parametric deformations. The data entered for the adjustment of the model was a sequence of left ventricle volumes. An echocardiograph examination yielded these volumes. We adapted a computer-controlled electro-mechanic device to the echocardiograph equipment that allows acquiring 60 sections in a rotational 3-D sampling. A cardiology specialist segmented these volumes. The minimization of the distance between the model and the corresponding points to the internal or external walls of the left ventricle was defined as the objective function. We minimized the energy of the error using the method of gradient descending for several variables. All parameters are adjusted simultaneously, recovering from the model the dynamic of the position, orientation, size, torsion and form. We successfully adjusted the model to the sequence formed by 13 volumes of actual cardiac data. This approach allows us to obtain "clinically useful" results, since we get, separately and independently, the information of the form and movement parameters of the left ventricle. When we quantitatively compare the volume of the left ventricle and the volume of the model developed as a function of the time elapsed, we observed a small error, less than 2% in the calculation of the volume. Summarizing, a deformable superquadric obtains the global parameters of the left ventricle.