Significance of Increased TIhyphen;201 Uptake by the Lungs in Patients Undergoing Oral Dipyridamolehyphen;Thallium Myocardial Imaging

摘要

The purpose of this study was to evaluate the significance of increased TI-201 uptake by the lungs after oral dipyridamole testing. In conjunction with myocardial perfusion scintigraphy, intravenous dipyridamole has been recently approved as an alternative to exercise for the evaluation of coronary artery disease in patients who cannot adequately exercise, and it will largely replace oral dipyridamole testing. This study contributes to the understanding of the significance of increased lung thallium uptake during pharmacologic stress testing. Oral dipyridamole, 400 mg, was administered to 192 patients undergoing TI-201 imaging for clinical indications. Mild adverse effects occurred in 31percnt; of patients (chest pain, nausea, headache, or flushing). Dipyridamole had minimal hemodynamic effects. The lung/heart thallium activity ratio was determined in 152 patients. These were subdivided into four groups according to the presence or absence of ischemia, transient myocardial perfusion defect, or scar as indicated by a fixed myocardial perfusion defect. In 61 patients without transient myocardial perfusion defect or fixed myocardial perfusion defect (group 1), the lung/heart thallium activity ratio was 0.39 plusmn; 0.01 (mean plusmn; SEM). In 31 patients without transient myocardial perfusion defect but with fixed myocardial perfusion defect (group 2), the lung/heart thallium activity ratio was higher, 0.44 plusmn; 0.02 (P 0.05). In 27 patients with transient myocardial perfusion defect but no fixed myocardial perfusion defect (group 3) and in 33 patients with both transient myocardial perfusion defect and fixed myocardial perfusion defect (group 4), the lung/heart thallium activity ratio was 0.51 plusmn; 0.03 and 0.52 plusmn; 0.03, respectively, both significantly higher than either group 1 or group 2 (P 0.05). The frequency of patients with an abnormally increased lung thallium uptake (lung/heart thallium activity ratio 0.57) was higher in groups 2, 3, and 4 than in group 1. These results support the hypothesis that increased lung thallium uptake during 400 mg oral dipyridamole may provide additional evidence of ldquo;jeopardizedrdquo; myocardium.