QUANTITATIVE DIGITAL EVALUATION OF MYOCARDIAL EXERCISE TL-201 SINGLE-PHOTON EMISSION TOMOGRAPHY IN POSTMENOPAUSAL WOMEN

Quantitative computerized analysis of data from myocardial thallium-20 1 (Tl-201) single-photon emission tomography (SPET) may improve the di agnostic accuracy of coronary heart disease. The reference ranges for post-menopausal women are, however, limited and obtained mainly from p atients. To compare reference values from healthy postmenopausal women and to improve the quantitative analysis, 20 women (10 patients with coronary heart disease and previous infarction and 10 age-matched heal thy volunteers) were examined immediately post exercise and after a de lay. A nine-segment 'bull's-eye' model was used for analysis. At visua l evaluation, reproducibility was high (93%), no false-positive result s were obtained and in 70% of the patients the SPET was interpreted as abnormal. Using reported reference values for quantitative analysis, all the healthy women had an abnormal result. New reference values bas ed on three different methods of 'normalization' were calculated: the relative activity of segment 3 set to 100%, the segment with the highe st activity set to 100% and a least-squares method. They all differed significantly from those that had previously been reported. The freque ncies of agreement between visual and quantitative analysis were 84-92 % and were highest when segment 3 was used as a reference, but in thi s case only 40% of the patients with coronary heart disease had an abn ormal SPET. Using the least-squares method for handling digital inform ation, the SD of the normal values decreased and 90% of the patients w ith coronary heart disease were accurately diagnosed. These results pr ovide quantitative digital reference values for healthy postmenopausal women. They verify that quantitative analysis is in diagnostic agreem ent with visual evaluation, stress the need for local verification of reference ranges and suggest a least-square normalization method for t he analysis.