Biomedical Engineering Reference
In-Depth Information
15
ANALYSIS OF 4-D CARDIAC MR DATA WITH
NURBS DEFORMABLE MODELS: TEMPORAL
FITTING STRATEGY AND NONRIGID
REGISTRATION
Nicholas J. Tustison and Amir A. Amini
Cardiovascular Image Analysis Laboratory,
Washington University
St. Louis, Missouri 63110, USA
We present research in which both left- and right-ventricular deformation is estimated
from tagged cardiac mgnetic resonance imaging using volumetric deformable models con-
structed from nonuniform rational B-splines (NURBS). The four model types considered
and compared for the left ventricle include two Cartesian NURBS models — one with a
cylindrical parameter assignment and one with a prolate spheroidal parameter assignment.
The remaining two are non-Cartesian, i.e., prolate spheroidal and cylindrical, each with
their respective prolate spheroidal and cylindrical parameter assignment regime. These
choices were made based on the typical shape of the left ventricle. For each frame sub-
sequent to end-diastole, an NURBS model is constructed by fitting two surfaces with the
same parameterization to the corresponding set of epicardial and endocardial contours from
which a volumetric model is created. Using normal displacements of the three sets of or-
thogonal tag planes as well as displacements of contour/tag line intersection points and
tag plane intersection points, one can solve for the optimal homogeneous coordinates, in a
weighted least-squares sense, of the control points of the deformed NURBS model at end-
diastole using quadratic programming. This allows for subsequent nonrigid registration of
the biventricular model at end-diastole to all later time frames. After registration of the
model to all later time points, the registered NURBS models are temporally lofted in order
to create a comprehensive four-dimensional NURBS model. From the lofted model, we
can extract 3D myocardial deformation fields and corresponding Lagrangian and Eulerian
