Quantification of myocardial perfusion with myocardial contrast echocardiography during left atrial injection of contrast. Implications for venous injection.

Abstract

Myocardial perfusion can be quantified from time-intensity curves derived from the anterior myocardium after LA injection of contrast. Background-subtracted peak video intensity in this situation correlates closely with MBV. When MBV and MBF are closely coupled, such as during inotropic stimulation of the heart, background-subtracted peak video intensity also correlates closely with MBF. Since there are similarities in the models of LA and venous injections, these data indicate that it may be feasible to quantify myocardial perfusion with myocardial contrast echocardiography after venous injection of contrast.

Quantification of Myocardial Blood Flow With Ultrasound-Induced Destruction of Microbubbles Administered as a Constant Venous Infusion

“…Because VI is proportional to the effective microbubble concentration within the beam thickness at any PI (when the relation between the two is linear 13 ), it will be proportional to d/E. Substituting for d, from equation 1, VI is proportional to vt/E.…”

“…13 Transmural MBF (mL ⅐ min Ϫ1 ⅐ g Ϫ1 ) to each of the 16 wedge-shaped pieces was calculated as the quotient of the summed flows to the individual segments within that piece and their combined weight. The perfusion bed of either the LAD or LCx was determined using intracoronary injections of Albunex (Molecular Biosystems).…”

“…13 This threshold results from suppression of electronic "noise," a narrow dynamic range, and compression of the signal to display it on the video monitor. To be detected in the myocardium, therefore, the concentration of microbubbles in the LV cavity must be very high.…”

“…Two important points are evident from these data. First, as long as the relation between microbubble concentration and VI remains within the linear range, 13 ␤ reflects velocity and is not affected by the concentration of microbubbles infused intravenously. Second, because changing microbubble concentration within the fibers is equivalent to changing the number of fibers containing the same concentration of microbubbles, these results indicate that the measurement of A actually reflects fiber CSA.…”

Combined Assessment of Myocardial Perfusion and Regional Left Ventricular Function by Analysis of Contrast-Enhanced Power Modulation Images

“…9 Despite creative approaches and promising results, quantification or even imaging of myocardial perfusion has required extensive offline analysis, 10 remaining a goal of future research, 4,6,11,12 and the assessment of LV function with contrast remains subjective. No established technique for automated endocardial border detection and quantification of either global or regional LV function is applicable to contrast-enhanced images.…”