A multidimensional dynamic quantification tool for the mitral valve

OBJECTIVES: The mitral valve (MV) is a complex three-dimensional (3D) intracardiac structure. 3D transthoracic and transoesophageal echocardiography are used to evaluate and describe the changes in the mitral valve apparatus due to degenerative or functional mitral regurgitation. These techniques are, however, not accurate enough to capture the dynamic changes during the cardiac cycle. We describe a novel multistage modelling (MSM) technique, using three-dimensional transoesophageal echocardiography (3D TOE), to visualize and quantify the MV during all the phases of the cardiac cycle. METHODS: Using 3D TOE, sets of images were obtained from 32 individuals who were undergoing surgery for other reasons and who did not have MV disease. These images were divided into six steps whereby every step represented one cardiac cycle. The image sets were then cropped and sliced at the level of MV, then imported and segmented by the open source software (3D Slicer) to create 3D mathematical models. The models were synchronized with patient's ECGs and then reunited and exported as multiphase dynamic models. The models were analysed in two steps: (i) direct step-by-step visual inspections of the MV from various angles and (ii) direct measurements of anteroposterior, intercommissural, anterolateral-posteromedial diameters, anterolateral angles and anteroposterior angles in systole and diastole at different levels. RESULTS: The segmentation results in 32 x 6 high-quality cropped MV. The division of models into six steps allows quantification and tracking of MV movement. Reunion of the models leads to creation of a full real-time simulation of the MV during the cardiac cycle. Synchronization of the models with ECG enables accurate simulation. Measurements of the diameters showed: median intercommissural diameters were increased with 10% from mid-systole to mid-diastole [31.9 mm (28.9-34.9), 34.8 mm (31.2-38.2), respectively, P-value