Thallium myocardial imaging: recent experience using a coronary vasodilator.

Thallium-201 myocardial imaging is an important test in the assessment of patients with suspected coronary artery disease. Techniques differ in detail, reliability and in patient acceptability. Three techniques have been compared. Thirty-two-patients were studied in three groups. In the first group (15 patients) exercise thallium scans were compared with scans following an intravenous vasodilator (dipyridamole). In the second group (12 patients) intravenous dipyridamole and oral dipyridamole thallium scans were compared. In the third group (five patients) combined oral dipyridamole and exercise scans were assessed. There were no major differences in the first two groups but the combined test showed a marked increase in image quality and diagnostic yield. Thallium scanning is simplified considerably by the use of oral dipyridamole, without loss of diagnostic quality of safety. It promises to be the method of choice for stress scanning, and is ideal in patients unable to tolerate maximum exercise. The combined exercise--dipyridamole scan helps to evaluate complex problems, particularly those with less severe coronary insufficiency, and can be done without the use of a treadmill.