Biventricular myocardial kinematics based on tagged MRI from anatomical NURBS models

We present current research in which both left and right ventricular deformation is estimated from tagged cardiac magnetic resonance imaging using volumetric deformable models with a nonuniform rational D-splines (NURBS) basis. From a set of short and long axis images, the initial NURBS model is constructed by fitting two surfaces with the same parameterization to the set of epicardial and endocardial contours from which a volumetric model is created. Using displacement information derived from tag line and contour data, we can solve for the optimal homogeneous coordinates, in a least-squares sense, of the NURBS model at a later time point using quadratic programming. After fitting to all time points of data, lofting the NURBS model for each time point creates a comprehensive 4-D NURBS model. From this model 3-D myocardial displacement fields and corresponding strain maps, which are local measures of nonrigid deformation, become available.