TOMOGRAPHIC ASSESSMENT OF LEFT VENTRICULAR MASS IN NORMAL AND INFARCTED CANINE HEARTS USING A NEW AUTOMATED EDGE-DETECTION PROGRAM

Abstract

We evaluated a new automated edge detection program to determine the feasability of determining left ventricular (LV) mass from single photon emission tomography (SPECT) of thallium-201 (T1) images in 7 dogs. Two of the seven dogs underwent repeat SPECT imaging 4 hours after coronary artery occlusion, with a closed-chest technique. All studies were obtained with the animal sedated and without gating. True LV mass was determined at sacrifice within one hour of the last Tl study. LV mass determined by SPECT correlated well with measured LV mass (r = .81; p < .05) over a range of 90 to 156 grams. The mean intra-observer error with the new automated technique was 3.8 gm. In the two dogs who had a control and post infarct study, total LV mass by SPECT varied by less than 4 grams (+3%). We conclude that SPECT tomography can define LV mass accurately and reproducibly in this model. The ability of the SPECT LV mass program to detect both normal and infarcted tissue suggests the possibility of (1) documenting interventions designed to alter LV mass and (2) of sizing acute infarcts and assessing interventions that may alter acute infarct size.