LEFT VENTRICULAR VOLUMES ESTIMATIONS USING A TOMOGRAPHIC COUNT BASED METHOD

Abstract

Forty consecutive patients with coronary artery disease, myocardial infarction or valvular disease were evaluated by contrast ventriculography and gated blood pool emission tomography (GBPS). Left ventricular end-diastolic (EDV) and end-systolic volume (ESV) were assessed with both techniques. After tomographic reconstruction of the slices, transverse and sagittal images were obtained by addition of all ventricular 1 pixel thick slices in order to preserve the counts-blood volume relation. LV ROIs were determined using a threshold at 45% of maximum activity, while the stroke volume image defined the valvular planes. The position of the LV ROI centers of gravity were computed on each orthogonal plane. The activity of the center of gravity pixel on the transverse LV ROI represents the activity measured thru the thickness of the LV volume. The thickness is determined on an orthogonal slice (sagittal) at its center of gravity. The center of gravity of LV transverse ROI is assumed to correspond to the center of gravity of the LV sagittal ROI. The sum of counts in the transverse LV ROI was scaled by the value obtained for each of the pixels on the sagittal slice, and the same reverse processing was performed for sagittal volumes. Four volumes were computed for each patient (EDV transv., EDV sag., ESV transv., ESV sag.) and also mean (transv. sag.) EDV and ESV. The correlations between contrast single plane ventriculography and tomography are: r=.85 for transverse volumes, r=.87 for sagittal volumes and r=.88 for mean volumes (S.E.E. = 34.1 ml).