[Dipyridamole-loading scintigraphy in patients with subendocardial infarction using single photon emission computed tomography].

To detect myocardial lesions in patients with subendocardial (nontransmural) infarction, myocardial perfusion images of thallium-201 (T1-201), using single photon emission computed tomography, were obtained in 17 patients during and three hours after coronary vasodilatation induced by the administration of dipyridamole. Controls consisted of 28 patients with transmural infarction and 11 with angina pectoris. Dipyridamole was infused intravenously at a rate of 0.142 mg/kg per min for four min, and the washout rate of T1-201 was calculated by the segmental ROI method. The results were as follows: 1. Many patients with nontransmural infarction exhibited various T1-201 myocardial perfusion images. 2. The prevalence of redistribution among patients with nontransmural infarction was 88.2% (15 of 17), and its reverse redistribution was 64.7% (11 of 17). Every subject exhibited a number of abnormal T1-201 myocardial perfusion images. 3. In patients with nontransmural infarction the occurrence of reverse redistribution images was significantly higher (64.7%) compared to those with transmural infarction (10.7%), and the occurrence of redistribution images was significantly higher (88.2%) compared to those with angina pectoris (45.5%). 4. The abnormal perfusion images most frequently present in the areas corresponding to the sites of ST-T changes on ECG were reverse redistribution (26.7%), redistribution (17.3%), and fixed defect (6.7%) in order. 5. The phenomenon of reverse distribution images was found irrespective of stenotic coronary artery lesions on selective coronary angiography. Most areas corresponding to the sites of reverse redistribution showed ST-T changes on ECG and high washout rates of T1-201. In conclusion, these findings suggest reflections of uneven coronary blood flow and the mixed normal and scarred myocardium in patients with nontransmural infarction.