[Assessment of relative washout rate (rW-R) in stress T1-201 myocardial SPECT].

Stress T1-201 myocardial SPECT was performed and evaluated quantitatively by Bull's eye method in 54 patients with single vessel coronary artery disease (33 angina pectoris, 21 myocardial infarction) who underwent successful PTCA. As the index of myocardial ischemia and viable muscle that was not affected by work load and others, relative washout rate (rW-R) was calculated from the formula: washout rate (W-R) of ischemic area was divided W-R of normal area. The purpose of this study was to examine the significance and usefulness of rW-R. Good correlation was recognized between grade of coronary artery stenosis, severity score (Sv-S) and rW-R in 28 patients with effort angina pectoris (EAP). Therefore, rW-R was regulated with coronary flow in EAP. On the other hand, in 5 patients with vasospastic angina (VSA), there was a tendency that rW-R showed low value compared with Sv-S. It was suggested that rW-R in patients with VSA was regulated not only coronary flow but also other factors. As a result of study before and after successful PTCA, rW-R foresaw the improvement of coronary perfusion and work load capacity by successful PTCA exactly. It was concluded that W-R reflected myocardial ischemia and myocardial viability accurately, and rW-R was a useful clinical index.