Evaluation of hepatic steatosis by ultrasound in patients with chronic hepatitis C virus infection.

OBJECTIVE

To compare two alternative ultrasound parameters, hepatic vein flow (HVF) pattern and presence of focal hypoechoic areas (FHA) within the liver hilus, as non-invasive predictors of liver steatosis in patients with chronic hepatitis C virus (HCV) infection.

DESIGN

In 122 consecutive patients with chronic HCV infection, the HVF pattern and presence of FHA within the liver hilus were assessed by Duplex-Doppler and B-mode sonography. All patients underwent liver biopsy and the sonographic results were compared with a histological score of steatosis used as the gold standard for this purpose. Association of fatty infiltrations with clinical and sonographic features were evaluated by a stepwise logistic regression analysis.

RESULTS

Reduced HVF and FHA, but not standard clinical and laboratory parameters, strongly correlated with steatosis on histology (P<0.001). Both sonographic parameters made excellent predictions for the subgroup of patients with severe steatosis, particularly when both tests were combined [sensitivity (SE) 95%, specificity (SP) 96%, positive predictive value (pPV) 93%, negative predictive value (nPV) 97%, and accuracy 96%]. However, the sensitivity and accuracy of HVF pattern analysis were markedly reduced when all degrees of steatosis were defined as positive (SE 71%, SP 76%, pPV 81%, nPV 64%, and accuracy 73%). In contrast, the dichotomous parameter FHA remained a powerful indicator even under the latter conditions (SE 74%, SP 100%, pPV 100%, nPV 72%, and accuracy 84%). The combination of both sonographic tests resulted in improved sensitivity (82%), but significant loss of specificity (76%) and accuracy (80%) for prediction of liver steatosis.

CONCLUSION

Sonographic evaluation of reduced HVF and FHA within the liver hilum is easy to perform, non-invasive, and, when present, gives a high degree of confidence in the diagnosis of liver steatosis. However, the lack of sonographic evidence of steatosis cannot definitively exclude the presence of mild steatosis, as shown on biopsy.