Real-time visualization of myocardial perfusion and wall thickening in human beings with intravenous ultrasonographic contrast and accelerated intermittent harmonic imaging

Previous work has demonstrated that at higher peak negative pressures, micr obubbles are destroyed by diagnostic ultrasonography. At lower pressures (l ower mechanical index), less destruction occurs but enhanced contrast persi sts. In animals, this lower mechanical index has resulted hi enhanced contr ast after administration of intravenous microbubbles with intermittent imag ing at faster frame rates. We tested whether this accelerated intermittent imaging technique could produce myocardial contrast and detect myocardial p erfusion abnormalities in 25 patients (10 with normal wall motion, 15 after myocardial infarction). Three independent reviewers detected persistent my ocardial contrast defects within the infarct zone throughout the cardiac cy cle in 9 of the 15 patients after acute myocardial infarction; the presence of such defects was predictive of a persistent regional wall motion abnorm ality at 4-week follow-up. Interobserver agreement on regional contrast enh ancement ranged from 88% to 90%. We conclude that accelerated intermittent imaging permits real-time visualization of myocardial blood flow and wall t hickening. (J Am Soc Echocardiogr 1999;12:266-71.).