Quantification of myocardial perfusion using intravenous myocardial contrast echocardiography in healthy volunteers: comparison with positron emission tomography.

BACKGROUND

Intravenous myocardial contrast echocardiography (ivMCE) has the potential to evaluate myocardial contraction and perfusion simultaneously. The purpose of this study was to assess quantification of myocardial blood flow (MBF) using ivMCE and to compare this with MBF as measured with positron emission tomography (PET).

METHODS

A total of 16 healthy volunteers underwent ivMCE using power pulse inversion and contrast agent microbubbles at rest and during pharmacologically induced vasodilation. Microbubble destruction was achieved with a burst of high-energy ultrasound, followed by imaging of contrast replenishment with low-energy ultrasound. Regions of interest were drawn and time intensity curves were calculated that were fitted to a monoexponential function. An estimate of MBF (perfusion estime) was calculated as the product of the plateau value A and the exponential beta describing the replenishment curve. MBF was measured with PET using oxygen-15-labeled water at rest and during adenosine stress.

RESULTS

Significant correlations were found between MBF as measured with PET and perfusion estimate as measured with ivMCE in the left anterior descending coronary artery (r = 0.87, P < .01), right coronary artery (r = 0.66, P < .01), and left circumflex artery (r = 0.75, P < .01) territories. Heterogeneity, however, was significantly larger for ivMCE (coefficient of variation 32 +/- 15%) than for PET (9 +/- 6%) measurements (P < .01).

CONCLUSION

Perfusion parameters as measured with ivMCE correlated with PET-derived MBF, but associated heterogeneity was significantly larger. Currently, this heterogeneity precludes true quantification of MBF using ivMCE.