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 hypoechoeic areas (FHA) within the liver hilus, as non-invasive predictors for 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, respectively. All patients underwent liver biopsy and sonographic results were compared to a histological score of steatosis as gold standard.
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 (SE 95%, SP 96%, pPV 93%, nPV 97% and accuracy 96%). However, sensitivity and accuracy of HVF pattern 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 condition (SE 74%, SP 100%, pPV 100%, nPV 72%, and accuracy 84%). 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 hilus is easy to perform, reproducible and, when present, gives a high degree of certainty for the diagnosis of liver steatosis.