Repeatability of the "flash-replenishment" method in contrast-enhanced ultrasound for the quantitative assessment of hepatic microvascular perfusion

This study aimed to evaluate the feasibility and repeatability of the flash-replenishment method in contrast-enhanced ultrasound (CEUS) perfusion imaging and assess quantitatively microvascular perfusion in the liver. Twenty healthy New Zealand rabbits were submitted to CEUS perfusion imaging with continuous intravenous infusion. Using flash-replenishment kinetics, the dynamic process of depletion and refilling of microbubble contrast agent was recorded. The hepatic microvascular perfusion parameters were calculated, including region of interest, peak intensity (PI), area under the curve (AUC), and hepatic artery to vein transit time (HA-HVTT). A consistency test was performed for multiple measurements by the same operator and blind measurements by two different operators. The hepatic perfusion imaging of 3×108 bubbles/min had minimal error and the best imaging effect and repeatability. The variability of the perfusion parameter measured at 3 cm depth under the liver capsule was at a minimum with coefficient of variation of 3.9%. The interclass correlation coefficient (ICC) of measurements taken by the same operator was 0.985, (95% confidence interval, CI=0.927-0.998). Measurements taken by two operators had good consistency and reliability, with the ICC of 0.948 (95%CI=0.853-0.982). The PI and AUC of liver parenchyma after reperfusion were lower than before blocking; and HA-HVTT was significantly longer than before blocking (P<0.05). The flash-replenishment method in CEUS perfusion imaging showed good stability and repeatability, which provide a valuable experimental basis for the quantitative assessment of hepatic microvascular perfusion in clinical practice.

Quantitative assessment of hepatic fibrosis by contrast-enhanced ultrasonography / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To explore the contrast-enhanced ultrasonographic features for quantitative assessment of hepatic fibrosis.</p><p><b>METHODS</b>86 patients with chronic viral hepatitis B were enrolled in this study from March 2007 to August 2009. The patients were classified into 5 groups (S(0)-S(4)) according to fibrosis stage evaluated with ultrasound guided liver biopsy. New contrast-enhanced ultrasonography (CEUS) features including area under the time-intensity curve (TIC) of portal venous phase/hepatic arterial phase (Qp/Qa) and intensity of portal venous phase/hepatic arterial phase (Ip/Ia) were used to detect the blood supply ratio (portal vein/hepatic artery) in each group. Arrival time of portal vein trunk (Tp) and decreasing rate of TIC (β) were also analyzed.</p><p><b>RESULTS</b>Qp/Qa and Ip/Ia decreased from S(0) to S(4), while Tp and β increased. These 4 features were significantly correlated with the degree of fibrosis (P<0.001) and were significantly different among the five groups (P<0.001). Sensitivity and specificity of Ip/Ia were 80% and 86% for groups ≥S(1), 75% and 86% for groups ≥ S(2), 71% and 84% for groups ≥ S(3), and 76% and 80% for group S(4), respectively. Sensitivity and specificity of Qp/Qa were 70% and 88% for groups ≥ S(1), 80% and 76% for groups ≥ S(2), 74% and 70% for groups ≥ S(3), and 81% and 95% for group S(4), respectively.</p><p><b>CONCLUSION</b>Ip/Ia and Qp/Qa could be adopted as reliable, non-invasive features for quantitative assessment of hepatic fibrosis.</p>