PET software for measurement of left ventricular myocardial viability, enlargement and geometric distortion

The authors developed software to aid in the evaluation by positron emission tomography (PET) of critical determinants of improvement following re-vascularization including the amount of viable tissue, quantified from myocardial oxygen consumption, and left-ventricular (LV) cavity enlargement and LV geometry, determined from ECG-gated blood pool images. Viable and non-viable tissue are determined from polar displays by comparison with normal subjects. The LV is isolated on the blood pool studies by assignment of regions of interest on beating images in the short-, vertical long- and horizontal long-axes. LV size is then determined from the total number of voxels in the LV cavity. The geometry of the LV is assessed by a sphericity index representing the ratio of the measured LV volume to the volume of a sphere with diameter equal to the long-axis dimension of the actual ventricle. These measurements were validated by imaging of a plastic phantom and by patient studies.