REGIONAL DISTRIBUTION OF MYOCARDIAL BLOOD-FLOW MEASURED BY SINGLE-PHOTON EMISSION TOMOGRAPHY - COMPARISON WITH INVITRO COUNTING

Abstract

An emission computed tomography system (SPECT), which uses a single large-field-of-view gamma camera, was evaluated for its ability to measure the relative distribution of myocardial blood flow and to assess the effects of attenuation, scatter and cardiac motion on the tomographic images. Normalized regional myocardial counts from the SPECT images of the living dogs correlated closely with those from the anatomic slices and the samples counted at necrospy except for an overestimate of tracer in the perfusion defect (SPECT) 57.7 compared to tissue count 32.1; P < 0.05. The differences were less for the other imaging conditions. Heart and thorax motion, attenuation and scatter contributed < 25% to the overestimate of defect counts. The SPECT system accurately reflects regional distribution of myocardial blood flow except for overestimation of flow in regions of perfusion defects. Smal perfusion defects might be missed, but no artifactual defects are created.