Quantificationof Rotational Thaffium-201MyocardialTomography

otational myocardial tomography after injection of thallium-201 at peak exercise has been suggested as a significant improvement over planar scintigraphy for the detectionand localizationof myocardialischemia(1—4). Rotational thallium-201 tomography at rest has also been reported to be better than planar imaging for the detection and localization of myocardial infarction (5—7),as well as for estimations of the extent of the in farct (6,7). Despite increasing availability of methods for quantifying planar Tl-201 myocardial scintigraphy (8—12),current evaluation of regional myocardial per fusion from stress/redistribution rotational tomography is usually made by visual interpretation of the recon structed T1-201tomograms.This approachis limited by observervariability,inabilityto account for differences in regional photon attenuation, inability to assess myo cardial washout, inability to quantify the percentage of the myocardium that is involved with either a perfusion defect or a washout abnormality, and the time-con