An Original Methodology for Quantitative Assessment of Perfusion in Small Animal Studies Using Contrast-Enhanced Ultrasound

The aim of this paper was to validate the combination of two original methods for assessing perfusion in small animal studies using contrast-enhanced ultrasound. Respiratory motion was first removed using a frame selection method. This method, based on a principal component analysis, enabled the definition of two subsequences, corresponding to the end-of-inspiration plane and to the end-of-expiration plane. Attenuation caused by contrast agent microbubbles was then estimated. The developed method, based on the assumption that a linear relationship holds between local attenuation and backscatter, used the time-intensity variation in a highly echogenic distal area without contrast uptake to estimate local attenuation coefficients. Ten murine renal perfusion studies were investigated after a bolus injection of SonoVue. Replenishment kinetics were acquired too and were finally modeled with an exponential function. Preliminary results were promising. Indeed, the SonoVue concentration was more faithfully represented than on native images, which allowed a better assessment of perfusion parameters in the whole field of view.