[Tc-99m MIBI myocardial scintigraphy in evaluation of the effect of percutaneous transluminal coronary angioplasty on coronary artery stenosis].

Tc-99m 2-Methoxy-Isobutyl-Isonitrile, a newly developed myocardial perfusion radiopharmaceutical for myocardial perfusion imaging, provides an accurate, noninvasive detection of coronary artery disease. The potential advantages of Tc-99m MIBI over T1-201 have been reported extensively. The purpose of this study is to evaluate the detectability of the diseased vessels and the effectiveness of percutaneous transluminal coronary angioplasty (PTCA) on Tc-99m MIBI myocardial perfusion scan. Twenty cases of coronary artery disease were included. Single photon emission computed tomographic (SPECT) imagings were used. Forty myocardial imagings were done before and after PTCA. Twenty nine segments of perfusion defect were found preoperatively. The sensitivity and specificity for the images to detect the individual coronary arteries were 88% and 94%, respectively. After PTCA, 25 out of 29 perfusion defects (86%) resolved. Among these, 14 were transient defects (93%) and 11 were persistent defects (79%). Persistent defects on serial thallium and Tc-99m MIBI scans are commonly thought to represent fibrosis or scar. Some investigators suggest that the recovered persistent defects on thallium scan represent hypoperfusion of viable myocardium. In our study, we found that regions of persistent defects on Tc-99m MIBI scan often revert to normal-state after PTCA (79%), indicating the similar results on thallium scans. In conclusion, Tc-99m MIBI myocardial imaging is useful in detecting coronary artery disease and monitoring success of PTCA.