Quantification of 3D left ventricular deformation using hyperelastic warping: comparisons between MRI and PET imaging

Image based finite element (FE) analysis was used to determine the deformation of the left ventricle (LV) between end-systole and end-diastole. The algorithm used volumetric MRI data to create a body force that deformed a finite element model of the LV over half of the cardiac cycle and tracked the tissue deformation. The accuracy of the computational predictions of strain were assessed by the creation of image data sets for which displacements between the images were known. A "forward" left ventricular FE model was given physiological loading and material properties. A loaded magnetic resonance imaging (MRI) data set was created by displacing the end-systolic image MRI data set using the displacement values determined from the forward model. The strains computed from the forward and Warping solutions were compared. Further, PET images from a single patient were analyzed and compared to MRI-based Warping analysis results for the same patient at mid-ventricle and at the base of the LV. The fiber stretch distribution between the forward and warping solutions show good agreement, both in overall stretch distribution and for the stretch values on the image planes. The MRI and PET analyses showed similar stretch distributions indicating that strain distributions can be measured from PET images.