Hepatic artery resistive index (HARI) and non-alcoholic fatty liver disease (NAFLD) fibrosis score in NAFLD patients: cut-off suggestive of non-alcoholic steatohepatitis (NASH) evolution

Purpose of the study: Conventional ultrasound (US) is reliable to reveal the presence of non-alcoholic fatty liver disease (NAFLD), but it is neither sensitive nor specific to reveal fibrosis clues, except in advanced stages where signs of cirrhosis are evident. NALFD fibrosis score is a non-invasive parameter that predicts well the presence of significant fibrosis, but correlations with US parameters are lacking. The aim of this study was, therefore, to compare resistive index of hepatic artery (HARI) of NAFLD patients with different severity degrees of diffuse fatty liver disease vs HARI of controls, and to compare HARI of NAFLD patients with different NAFLD fibrosis scores vs HARI of controls. Methods: This was a spontaneous, no-profit observational study conducted in our US department between December 2013 and July 2014. Patients with NAFLD with different severity of disease and healthy controls were included. Echogenicity and size of liver and spleen, maximum portal vein velocity, RI, peak systolic velocity (PSV), and end diastolic velocity (EDV) of splenic artery, PSV, EDV, and RI of hepatic artery, and NAFLD fibrosis score were acquired and compared between groups. Results: HARI was significantly lower in NAFLD patients than controls (p < 0.0001). A significant difference was also found between the groups of NAFLD severity (p < 0.0001). There was also a difference between HARI of NAFLD patients with different NAFLD fibrosis scores vs HARI of controls (p < 0.0001) with a positive correlation between HARI and NAFLD fibrosis score. Conclusion and discussion: Conventional Doppler US can be helpful to detect NAFLD patients with the risk of fibrous tissue accumulation. HARI tends to exceed the range of controls for patients with NAFLD fibrosis score greater than 0.675. The detection of HARI greater than 0.9 in NAFLD patients, regardless of the US degree of severity of steatosis, might suggest the execution of biopsy to predict the risk of progression to steatohepatitis and fibrous tissue accumulation. Low values of HARI may be expression of lower risk, which does not necessitate any biopsy.