Thallium-201 scintigraphy after dipyridamole infusion in patients with ischemic heart disease

Myocardial images after dipyridamole infusion (DIP-Tl) were compared with maximal thallium-201 images (Ex-Tl) to determine the utility for detecting coronary artery disease and the ischemic level in ischemic regions. Ex-Tl was performed in 36 patients with angina pectoris (Group 1), and DIP-Tl was performed in 22 patients with angina pectoris (Group 2), who were divided into two groups (Group 2a: 15 patients with low level exercise, Group 2b: 7 patients without low level exercise). Each group had normal controls (41, 27 and 31 people). The detectability of coronary artery by DIP-Tl was almost the same as Ex-Tl (sensitivity 85% vs. 86%, specificity 80% vs. 95%). In the case of normal controls, the mean washout rate of group 2b was 44.4%, which was less than the other two groups (50.6% for group 1, 48.8% for group 2a). And the mean myocardial/ bachground (M/B) ratio of group 2b was 4.3 less than the other two groups (4.7 for group 1, 4.9 for group 2a). In the case of the patients with angina pectoris, washout rate, M/B ratio, initial % uptake and delayed % uptake in the ischemic raegion were almost the same among the 3 groups. This study demonstrates that DIP-Tl is as effective as Ex-Tl, and the ischemic level in the ischemic region is almost the same among the 3 groups. But the thallium accumulation in the background of the group 2b is slightly higher than the other two groups in the normal controls, so it is suggested that the image after only dipyridamole infusion becomes slightly unclear. (author)