Imaging of nonalcoholic steatohepatitis: advantages and pitfalls of ultrasonography and computed tomography.

OBJECTIVE The present study was performed to clarify the ability of ultrasonography (US) and computed tomography (CT) to detect steatosis and advanced fibrosis in nonalcoholic steatohepatitis (NASH) patients, and to assess the influence of steatosis, fibrosis, and obesity on the radiological detection of steatosis and advanced fibrosis. METHODS One hundred and eighteen biopsy proven NASH patients underwent US and CT within 6 months before or after biopsy. The ability of US and CT to detect histological steatosis and advanced fibrosis was assessed. To evaluate whether fibrosis and obesity interfered with the detection of moderate to severe histological steatosis by US and CT, we analyzed 88 NASH patients with moderate to severe steatosis. To evaluate interference with the detection of advanced fibrosis by steatosis and obesity, we analyzed 59 NASH patients with advanced fibrosis. RESULTS The sensitivity of US for detecting moderate to severe histological steatosis in patients with mild histological fibrosis was 100%, but this was reduced to 77.8% in patients with advanced histological fibrosis (p=0.001). The sensitivity of CT was 69.8% in patients with mild histological fibrosis and 48.9% in those with advanced histological fibrosis (p=0.047). The sensitivity of US and CT for moderate to severe histological steatosis was similar in each body mass index group. The sensitivity for detecting advanced fibrosis was markedly decreased by severe steatosis and obesity in the case of both US and CT. CONCLUSION If we are aware of these disadvantages of US and CT, it is useful for diagnosing steatosis and fibrosis in NAFLD patients.