Relationship between portal blood flow measured by image-directed Doppler ultrasonography and hepatic blood flow measured by indocyanine green constant infusion in patients with cirrhosis

The validity of portal blood flow measurement in image-directed Doppler ultrasound (PBF-IDU) is still under debate. In this study PBF-IDU has been compared with hepatic blood flow measured by the indocyanine green constant infusion technique (HBF-ICG), which is the reference invasive method with which to measure total hepatic blood flow in man (ie, the sum of hepatic artery and portal vein blood flow). In 27 cirrhotic patients with hepatopetal portal blood flow, PBF-IDU was measured by multiplying the portal vein cross-sectional area by the averaged mean velocity of blood in the vessel. About 1 hour later HBF-ICG was measured during hepatic vein catheterization performed to evaluate portal hypertension. In 19 of 27 patients, intrahepatic arterial resistance indices were also measured. PBF-IDU and HBF-ICG were 1.010 +/- 0.555 L/min (M +/- SD) and 1.496 +/- 0.731 L/min, respectively. Blood flow measured by the two methods showed a close correlation (r = 0.80, p < 0.001). The regression line showed that HBF-ICG was systematically higher than PBF-IDU (mean difference +29 +/- 30%). The hepatic artery component of HBF-ICG probably accounted for the difference. An inverse correlation was found between the differences between the two procedures and intrahepatic arterial resistance indices (r = -0.52, p = 0.04), which may be considered indirect parameters of arterial supply. It can be concluded that image-directed Doppler ultrasound is a sufficiently accurate method to measure portal blood flow in cirrhotics.