In vitro quantification of flow using continuous infusion of Levovist and pairs of harmonic power Doppler images

To evaluate the potential of harmonic power Doppler to quantify perfusion u sing a continuous infusion of contrast, two dialysis cartridges were perfus ed with different flow rates adjusted between 0 to 300 mL/min, correspondin g to flow ratios comprised between 300:0 and 150:150, The contrast agent (L evovist((R)), Schering) was injected at constant rates (0.6 to 5 g/h), Sequ ential pairs of images showing simultaneously the cross-sections of the two filters were acquired with a HDI 5000 (ATL) and the Doppler data were proc essed with HDI lab software (ATL), The absolute values of the signal in the different regions-of-interest (ROI) were not closely related to how rate. At the opposite, the rapid signal decrease between the first and the second image of each pair was inversely proportional to the flow rate. An index o f perfusion [PerI = image 1/(image 1 - image 2)] was defined. It correlated closely with the absolute and relative flow rates. For the latter, the slo pes of regression were found to be independent of the infusion rate of Levo vist((R)), Thus, the use of pairs of images combined with a continuous infu sion of Levovist((R)) provide a quantification of perfusion. (E-mail: benoi t.diebold@egp.ap-hop-paris.fr) (C) 2001 World Federation for Ultrasound in Medicine & Biology.