Dipyridamole Stress Echocardiography and Ultrasonic Myocardial Tissue Characterization in Predicting Myocardial Ischemia, in Comparison With Dipyridamole Stress Tc-99m MIBI SPECT Myocardial Imaging

The purpose of this study was to validate whether dipyridamole stress ultrasonic tissue characterization with cyclic variation of integrated backscatter (CVIBS) compared with dipyridamole stress echocardiography and dipyridamole stress Tc99m-MIBI SPECT myocardial perfusion scintigraphy could predict myocardial ischemia in patients with chronic coronary artery disease. Twenty patients (16 M, 4 F) who had coronary angiography for stable angina pectoris were included in the study. Mean age was 62 +/- 8 years. The left ventricle was divided into 16 segments. Regional wall motion analysis and CVIBS measurements were obtained from 16 myocardial segments at rest and after dipyridamole (0.84 mg/kg) infusion. After 10 minutes, Tc-99m MIBI (10 mCi) was injected and SPECT myocardial imaging was performed. After 3 hours, 25 mCi Tc-99m MIBI was reinjected and rest images were obtained. A total of 320 ventricular wall segments were evaluated. Two hundred and six ventricular wall segments were supplied by stenotic coronary arteries and 114 segments were supplied by normal coronary arteries. Dipyridamole stress Tc-99m MIBI SPECT studies showed abnormal myocardial perfusion in 176 segments and normal perfusion in 144 segments. Transient regional wall motion abnormality was detected in 116 segments. A significant decrease in CVIBS after dipyridamole stress was detected in 184 segments. The sensitivity and specificity of dipyridamole stress echocardiography, Tc-99m MIBI SPECT, and CVIBS were 56% and 100%, 85% and 92%, and 89% and 100%, respectively, compared with the results from coronary angiography. Dipyridamole stress ultrasonic tissue characterization with CVIBS may provide more sensitive detection of myocardial ischemia than dipyridamole stress echocardiography and may be as valuable as dipyridamole stress myocardial perfusion scintigraphy.