[Statistical indices of 201Tl distribution in the myocardium]

A study was made of the diagnostic potentialities of a histogram analysis of scintigraphic count distribution on myocardium scans using 201Tl in 9 patients with dilated cardiomyopathy, 12 patients with coronary heart disease and 6 patients with primary pulmonary hypertension. Scans were recorded 10 min., 4 and 24 h after a single administration of 201Tl at rest in the front-forward, 45 degrees left forward oblique and left lateral projections. The heart area on a scan was marked by hand. Count distribution was represented by an intensity histogram. An array of 243 scans was processed independently by 2 operators of different professional skill. A man-machine classification procedure with algorithm teaching was implemented. The author showed a possibility of group distinction by scintillation count distribution in the heart area on myocardium scans using 201Tl, the distinguishing information being within the interval of 41-80% of maximum intensity in this area. Automatic marking of the heart area on a scan was found necessary to have an entirely automated system for distinguishing groups of examinees.