Correlation of ultrasound attenuation imaging versus MRI proton density fat fraction in non-alcoholic fatty liver

Background: Attenuation Imaging (ATI) is a novel method for assessment of hepatic steatosis, based on ultrasound attenuation by calculating attenuation coefficient which increases in the fatty liver condition. The previous published data comparing ATI and Magnetic Resonance Proton Density Fat Fraction (MR-PDFF) has moderate to high correlation coefficient (r=0.66-0.81). However, fatty liver is commonly associated with obesity which may be an influencing factor of the ATI measurement. Objective: The purpose of this study was to evaluate diagnostic accuracy of ATI in non-alcoholic fatty liver disease (NAFLD) compared to MRI-PDFF Materials and Methods: The 62 non-alcoholic fatty liver disease (NAFLD) patients with available ATI, MRI-PDFF, and MRE examination, excluding cirrhosis, history of significant alcohol drinking, and chronic liver condition were retrospectively evaluated. Results: The correlation coefficient (r) of ATI vs MRI-PDFF were in good correlation (r = 0.63-0.69, p<0.001). The inter-observer reliability of two observers was 100% with the Cohen kappa coefficient of 1.00 (p < 0.001).Area under the receiver operating characteristics of ATI for diagnosis of steatosis grade > 0 was 0.96 and for diagnosis of steatosis grade > 1 was 0.83. Conclusions: ATI is a novel ultrasound method to quantify the degree of fat deposition with a good correlation to MRI-PDFF with high interobserver’ reliability. Obesity commonly associated with fatty liver may be an interfering factor of ATI measurement.