Aims: To compare the accuracy of the ultrasound attenuation index (USAI) and hepato-renal index (HRI) for the diagnosis of hepatic steatosis (HS). Material and methods: Two hundred and twenty-four potential living hepatic donors underwent US and subsequent US-guided liver biopsy. The USAI was calculated from US images with an 8 MHz transducer and HRI was measured on sagittal images with a clear visualization of both the liver and kidney. Using histological degrees of HS as the reference standard, we compared the performance of USAI and HRI for diagnosing HS ≥ 5% and ≥ 30% by receiver operating characteristic curve analysis. The interobserver agreement was evaluated by using intraclass correlation coefficients (ICCs) or Bland–Altman statistics. Results: Histologic degree of HS was 0–70% (median, 5%). HRI showed a tendency towards higher accuracy than USAI for diagnosing HS ≥ 5% (the area under the ROC curve, 0.856 vs. 0.820; p= 0.279) and ≥ 30% (0.937 vs. 0.909; p = 0.378) without statistical significance. There was an excellent interobserver agreement for both USAI and HRI (ICC = 0.931 and 0.973, respectively). According to the Bland–Altman method, the 95% limits of difference between two readers for HS were −8.5% to 6.6% by USAI and −4.8% to 6.2% by HRI. Most patients would have the difference of calculated HS by USAI (74.0%) and HRI (96.0%) from different operators within a range of ±5%. Conclusions: Although statistically insignificant, HRI was superior to USAI for the diagnosis and quantitative estimation of HS in terms of diagnostic performance, including accuracy and reproducibility.
Noninvasive quantitative estimation of hepatic steatosis by ultrasound: a comparison of the hepato-renal index and ultrasound attenuation index.