Comparison between Planar View and SPECT View on the Dipyridamole Thallium 201 Myocardial Perfusion Scintigraphy

Exercise testing with Thallium imaging is widely used for the noninvasive evaluation of patients suspected of having coronary artery disease. However, many patients referred for stress testing connot exercise adequately for either physical or psychological reasons, and as a result may have nondiagnostic or suboptimal test results.

Intravenous dipyridamole in conjunction with Thallium imaging is as effective alternative method without exercise. But, myocardial imaging using the standard scintillation camera technique(planner view) is hampered by superposition of proximal & distal cardial walls and by the segmental nature of myocardial ischemia. For this reason, Single Photon Emission Computed Tomography(SPECT) reslut in high specificity & sensitivity rates for the detection of coronar artery disease compared with conventional technique.

So we performed dipyridamole Th-201 myocardial scintigraphy on 25 subjects who have suspicious angina or myocardial infarction instead of exercise Th-201 myocardial scintigraphy, and compared SPECT view with conventional plannar view.

The results obtained are as follows :

1) T1-201 scintigraphic findings in 17 patients with suspicious angina were as follows ; redistribution defect was seen in 4 cases in plannar view and 13 cases in SPECT view.

2) T1-201 scintigraphic findings in 8 patients with myocardial infarction were as follows ; in planner view, perfusion defect was seen in all cases and 1 cases of them, redistribution defect was accompained, and in SPECT view, perfusion defect was seen in all cases and 6 cases of them, redistribution defect was accompained.

3) During dipyridamole infusion, the mean systolic & diatolic pressure decreased from 133±22.7/86±13.5 to 121±23.9/78±13.1mmHg and the heart rate increased from 68±12.4 to 84±12.4beats/min.

4) Adverse effects of dipyridamole were noted in 14(56%) of the subjects, but in 12 of these, the symptoms were mild in severity and subsided spontanously.

To summarize, Dipyridamole-201 myocardial imaging is a useful and test for coronary artery disease, and the new tomographic technique, SPECT view, is more useful than the conventional plannar view.