Thallium-201 myocardial scintigraphy in coronary triple-vessel disease: an attempt to increase sensitivity using quantitative methods.

In order to increase the sensitivity of thallium-201 exercise scintigraphy in patients with triple vessel coronary disease (TVD), we first examined retrospectively myocardial scintigrams of 179 patients with TVD, as documented subsequently by cardiac catheterization. Ischemia had been diagnosed visually in 141 (79%), scar without ischemia in 25 (14%) and no apparent perfusion defect in 13 (7%) cases. The subset of TVD patients without scintigraphic ischemia (i.e. those with scar or no perfusion defect) was then compared to a control group with normal coronary angiography using four quantitative criteria: (1) in preset-count analog images, a quotient of the exposure times rest image/stress image; (2) in preset-time digital images, a quotient of counts/pixel in stress image/rest image using two different myocardial regions of interest (ROI); (3) a similar quotient using paracardial lung ROIs of three different sizes; (4) the absolute values of stress lung uptake. Quotients (1) and (2) were expected to be lower in TVD patients than in normal controls due to exercise-induced global ischemia, quotient (3) and value (4) were expected to be higher due to exercise-induced left ventricular dysfunction with increased lung uptake of thallium-201. All results showed a tendency to confirm these hypotheses; significant differences (P less than 0.05) between patients and controls were obtained in all lung quotients and in 3 of 12 myocardial quotients. No significant differences were observed in the exposure time quotients of preset-count images and in the stress lung uptake. Due to overlapping values, it was not possible to fix normal and pathological ranges of any quotient.(ABSTRACT TRUNCATED AT 250 WORDS)