Technical factors that influence the determination of microbubble transit rate during contrast echocardiography

The calculation of mean microbubble transit rate (MMTR) during contrast echocardiography provides information regarding the flow through and blood volume of a vascular system. Several technical factors can impact on the accuracy of MMTR determination. In this study, with computer simulation and in vitro and in vivo data, we systematically examined four such factors: the relationship between microbubble concentration versus videointensity, the size of the region of interest and the sampling rate used to derive time-intensity plots, and the method of deriving MMTR (direct numeric calculation vs use of a mathematic model). The results indicate that the effect of these technical factors on the estimation of MMTR can be significant.