Correlation of Myocardial Photoscanning and Coronary Angiography in Angina Pectoris

Abstract

With the availability and development of new radioisotopes and more sophisticated scanning instruments, the field of organ scanning has grown significantly. It is only logical that attempts would be made to visualize the heart and thus to study abnormalities of the myocardium. Blood pool scanning has been in use for a long time, but it does not differentiate between the volume of blood within the heart and the myocardial muscle itself. Myocardial scanning has been attempted with rubidium 86 (1) and chlormerodrin 203 (2). The high energy of the gamma emission from rubidium made it unsuitable for the study of myocardial disease in the human, and the studies with chlormerodrin 203 were only partially successful. Quinn et al. (3) investigated macroaggregated radioiodinated albumin, but this work has been done in animals only and has not been reported in humans. In February 1964, Carr et al. (4) reported on the detection of myocardial infarctions with cesium 131, which proved to be an almost ideal isotope for this study. Cesium has a 29.4 keV k-capture x ray with a half-life of 9.7 days. Carr was successful in demonstrating acute myocardial infarcts, which presented as cold areas within the myocardial outline. It was this work that aroused our interest and led to the present study. This study was undertaken to determine whether myocardial scanning with cesium 131 could detect significant degrees of coronary insufficiency in patients with angina pectoris. Patients who were referred to the coronary catheterization unit of the Department of Medicine of Baylor University Medical Center were selected for evaluation in conjunction with coronary angiography. Over 70 per cent of these patients had symptomatic anginal disease and were being evaluated for possible corrective surgery. The remaining 30 per cent were being evaluated to determine whether there was significant coronary disease present. In the present study no attempt has been made to correlate the degree of clinical angina present with the scans or with the coronary angiograms. This study was done purely to correlate the findings of coronary angiography and myocardial scanning with cesium 131. A total of 56 patients were scanned: in 10 of these myocardial scans or angiograms were unsatisfactory, leaving a total of 46 patients to be evaluated. The patient was scanned on the same day that coronary angiography was performed, usually two to three hours after angiography was completed. One to two and a half millicuries of cesium 131 was injected intravenously in a small bolus. Two to three hours after the injection, the patients were scanned in the supine and the left anterior oblique positions. The latter was picked because the coronary angiogram films were made in this projection. The scanning instrument was a Picker Magna Scanner with a 5-inch crystal.