title: Corrected quantification method to determine myocardial blood flow using real-time myocardial contrast echocardiography.
abstract: BACKGROUND
  The quantitative assessment of myocardial blood flow using real-time myocardial contrast echocardiography is based on a replenishment of bubble density after bubble destruction by high-power ultrasound exposure (burst). However, all microbubbles in the myocardial vessels are not necessarily completely destroyed, which results in unreliable data of the replenishment curve analysis.
  
  
  OBJECTIVE
  The aim of this study was to propose a corrected equation for the replenishment curve analysis based on the hypothesis in which the initial intensity just after burst should be equivalent to the baseline intensity before contrast infusion, and to examine whether the regional difference of myocardial perfusion parameters could be minimized by the use of corrected equation of replenishment curve.
  
  
  METHODS
  Myocardial opacification of the left ventricular short-axis view was observed using low mechanical index during infusion of Definity in open-chest dogs. Bubble destruction was set in two ways, either high (0 dB) or low (-11 dB) power burst. The videointensity (VI) of baseline before contrast infusion (f-value) was assumed as an initial intensity after complete bubble destruction. Changes of the VI after burst were fitted to both exponential functions: y = a (1 - e(-beta t)) + c (conventional equation) and y = a (1 - e(-beta(t - d))) + f (corrected equation). The c-value was the measured VI just after burst. The d-value was the hypothetical time of onset of the replenishment curve if all bubbles were completely destroyed. The plateau VI was defined as the A-value, which was the sum of a- and c-values or a- and f-values, respectively. The maximal difference of beta-value among myocardial regions was calculated by either equation.
  
  
  RESULTS
  The A-value was almost identical in either equation regardless of the acoustic power of burst. The beta-value by the conventional equation was higher after the incomplete burst than that after complete burst (0.45 +/- 0.12 vs 0.54 +/- 0.16). By contrast, the beta-value calculated by the corrected equation was almost identical despite complete or incomplete bursts (0.46 +/- 0.13 vs 0.48 +/- 0.15). The maximal difference of beta-value was significantly reduced by the use of corrected equation (conventional 0.24 +/- 0.14 vs corrected 0.18 +/- 0.10).
  
  
  CONCLUSIONS
  Variation of beta-value because of the incomplete bubble destruction can be minimized by using the corrected equation: y = a (1 - e(-beta(t - d))) + f. Further, the corrected equation can improve the regional variation of beta-value.
authors.affiliation: Division of Functional Diagnostic Science, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Otani
authors.forename: Kasumi
authors.initials: K
authors.lastname: Masuda
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Asanuma
authors.forename: Fuminobu
authors.initials: F
authors.lastname: Ishikura
authors.forename: Shintaro
authors.initials: S
authors.lastname: Beppu
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology*; D003326:Coronary Circulation / Q000502:physiology*; D004285:Dogs; D004452:Echocardiography / Q000379:methods*; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D045423:Microbubbles; D015203:Reproducibility of Results; D012212:Rheology / Q000379:methods*; D012680:Sensitivity and Specificity; D016277:Ventricular Function, Left / Q000502:physiology*