Phase analysis of radionuclide ventriculograms for the detection of coronary artery disease

Abstract

The value of phase analysis of multiple gated acquisition blood pool images for identifying wall motion abnormalities due to stress-induced ischemia was examined. Myocardial segments with an abnormal phase, i.e., delayed onset of wall motion, were localized on a phase distribution image of the LV and the synchrony of LV systolic wall motion was assessed from histograms of the LV phase distribution, i.e., the standard deviation (SD) from the mean of this peak, which was defined as SDP. Its upper limits of normal at rest and exercise were established in seven normals as the mean +2 SD and were 12 degrees at rest and 10 degrees at maximum exercise. Of the 56 patients, 37 had coronary artery disease (CAD), 11 had valvular disease but normal coronary arteries, and eight had normal coronary arteries, no valvular disease, but had either cardiomyopathy or typical angina. In the CAD patients, SDP was abnormal in 95% during exercise while only 86% had an abnormal ejection fraction (EF) response and/or exercise-induced wall motion abnormalities by visual interpretation. By contrast, in the 11 valvular heart disease patients, SDP was abnormal in only two despire exercise-induced wall motion abnormalities in five and an abnormal EF response in all 11. Thus although an abnormal EF response to exercise is a sensitive indicator of cardiac disease, it is, however like exercise induced wall motion abnormalities, not specific for CAD. By contrast, phase analysis not only permitted separation of wall motion abnormalities induced by ischemia from those associated with valvular disease, but was also an objective, highly sensitive, and specific indicator of regional myocardial ischemia.