Background: Myocardial perfusion (MP) can be assessed in real time when using a low mechanical index (MI) and harmonic imaging following an intravenous injection of contrast agent. The aim of the study was to determine the feasibility and accuracy of the real-time imaging of contrast echocardiography (MCE) for detecting myocardial perfusion defects at rest and during dobutamine stress echocardiography (DE) compared with 99m Tc MIBI SPECT. The study group consisted of 44 patients (24 men, 20 women, mean age 58.9+/-7.8) with suspected coronary artery disease (CAD). All patients underwent DE. Wall motion (WM) and segmental perfusion were estimated in real time before and at peak stress using a low MI (0.4) after 0.3 ml bolus injections of intravenous Optison. All patients underwent a rest and exercise 99mTc MIBI SPECT study (SPECT). A 16-segment model of the left ventricle was used for the analysis of MP, WM and SPECT by a blinded reviewer. All patients underwent coronary angiography. Significant coronary artery disease was defined as >60% luminal diameter stenosis.
Results: All patients had significant CAD. Twenty-nine patients had single-vessel and 15 patients had double-vessel disease. For all patients, agreement between MCE and SPECT was 89%, between MCE and WM -86%, and between SPECT and WM -82%. The agreement between MCE and SPECT for LAD, RCA and Cx territories was 81, 91 and 73%, respectively. The sensitivity of MCE and SPECT for detecting perfusion defects due to significant CAD (confirmed angiographically) was 97% and 93%, respectively, and the specificity was 93 and 84%, respectively.
Conclusion: MCE in real-time imaging with Optison has significant potential for the identification of MP abnormalities. MCE correlates very well with SPECT images.