Quantitative digital evaluation of myocardial exercise thallium-201 single-photon emission tomography in...

Quantitative computerized analysis of data from myocardial thallium-201 (201Tl) single-photon emission tomography (SPET) may improve the diagnostic accuracy of coronary heart disease. The reference ranges for post-menopausal women are, however, limited and obtained mainly from patients. To compare reference values from healthy post-menopausal women and to improve the quantitative analysis, 20 women (10 patients with coronary heart disease and previous infarction and 10 age-matched healthy volunteers) were examined immediately post exercise and after a delay. A nine-segment 'bull's-eye' model was used for analysis. At visual evaluation, reproducibility was high (93%), no false-positive results 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 based on three different methods of 'normalization' were calculated: the relative activity of segment 3 set to 100%, the segment with the highest activity set to 100% and a least-squares method. They all differed significantly from those that had previously been reported. The frequencies of agreement between visual and quantitative analysis were 84-92% and were highest when segment 3 was used as a reference, but in this case only 40% of the patients with coronary heart disease had an abnormal SPET. Using the least-squares method for handling digital information, the SD of the normal values decreased and 90% of the patients with coronary heart disease were accurately diagnosed. These results provide quantitative digital reference values for healthy post-menopausal women. They verify that quantitative analysis is in diagnostic agreement with visual evaluation, stress the need for local verification of reference ranges and suggest a least-square normalization method for the analysis.