Improved radionuclide ventricular analysis using a computerized non-homogeneous torso model

A computer-based technique has been developed to incorporate the effects of individual variation in thoracic anatomy on the attenuation of photons emitted during radionuclide assessment of left-ventricular (LV) volumes. A computerized nonhomogeneous torso model has been developed, based on the torso structure of the anthropomorphic MIRD-phantom developed by W.S. Snyder et al. (1969), with appropriate modification to allow for movement intrinsic to a centrally placed ellipsoidal LV during cardiac contraction. Anatomical details for construction of individual torso models were derived from orthogonal chest radiographs and two-dimensional echocardiograms. A Monte Carlo simulation of radionuclide angiography resulted in the derivation of a transmission factor, dependent on the individual torso geometry and LV volume, which is used to correct radionuclide count rate for photon attenuation. Preliminary results of early clinical trials suggest that this may improve diagnostic accuracy for LV volume estimation