Absolute myocardial blood flow determination using real-time myocardial contrast echocardiography during adenosine stress: Comparison with single-photon emission computed tomography

Objective: To assess the feasibility and diagnostic accuracy of real-time myocardial contrast echocardiography (MCE)-derived absolute myocardial blood flow for detection of myocardial perfusion abnormalities compared with simultaneous technetium 99 m sestamibi single-photon emission computed tomography (SPECT). Design: Prospective study. Setting: Tertiary-care medical institution. Patients: 79 patients with known or suspected coronary artery disease. Interventions: Simultaneous SPECT and real-time MCE during adenosine stress. Main outcome measures: Absolute myocardial blood flow (MBF, ml/min/g), microbubble velocity (β, min^-1), and reserve values. Endpoints included sensitivity, specificity, positive likelihood ratio (LR+) or negative likelihood ratio (LR-) and area under the curve (AUC) of the receiver operating characteristic curve. Results: Reserve measurements were feasible in 975 of 1343 segments (73%); of these, 130 segments (13%) were abnormal by SPECT. MCE perfusion parameters clearly distinguished abnormal from normal segments for β reserve (1.13 (0.99) vs 2.22 (1.36), p<0.001) and MBF reserve (1.80 (2.29) vs 3.69 (2.79), p<0.001). The β reserve cut-off of 1.60 provided the following: AUC, 0.787; sensitivity, 82%; specificity, 66%; LR+, 2.40; and LR2, 0.28. The MBF reserve cut-off of 1.90 provided the following: AUC, 0.779; sensitivity, 73%; specificity, 72%; LR+, 2.69; and LR2, 0.37. MBF reserve had an AUC of 0.773 for the left anterior descending coronary artery, 0.885 for the left circumflex coronary artery and 0.739 for the right coronary artery. Conclusions: Real-time MCE-derived absolute MBF, β, and reserve values are feasible and accurate for detecting myocardial perfusion abnormalities as defined by SPECT.