Novel Method for Ultrasound-Derived Fat Fraction Using an Integrated Phantom.

Objectives: The purpose of this study was to demonstrate the clinical feasibility of an integrated reference phantom method for quantitative ultrasound by creating an ultrasound-derived fat fraction (UDFF) tool. This tool was evaluated with respect to its diagnostic performance as a biomarker for assessing histologic hepatic steatosis and its agreement with the magnetic resonance imaging (MRI) proton density fat fraction (PDFF).

Methods: Adults (n = 101) with known or suspected nonalcoholic fatty liver disease consented to participate in this prospective cross-sectional study. All patients underwent MRI-PDFF and ultrasound scans, whereas 90 underwent liver biopsy. A linear least-squares analysis used the attenuation coefficient and backscatter coefficient to create the UDFF model for predicting MRI-PDFF.

Results: The area under the receiver operating characteristic curve values were 0.94 (95% confidence interval [CI], 0.85-0.98) for histologic steatosis grade 0 (n = 6) versus 1 or higher (n = 84), 0.88 (95% CI, 0.8-0.94) for grade 1 or lower (n = 45) versus 2 or higher (n = 45), and 0.83 (95% CI, 0.73-0.9) for grade 2 or lower (n = 78) versus 3 (n = 12). The Pearson correlation coefficient between UDFF and PDFF was ρ = 0.87 with 95% limits of agreement of ±8.5%. Additionally, the diagnosis of steatosis, defined as MRI-PDFF higher than 5% and 10%, had area under the receiver operating characteristic curve values of 0.97 (95% CI, 0.93-0.99) and 0.95 (95% CI, 0.9-0.98), respectively. The body mass index was not correlated with either UDFF or PDFF.

Conclusions: An on-system, integrated UDFF tool provides a simple, noninvasive, accessible, low-cost, and commercially viable clinical tool for quantifying the hepatic fat fraction with a high degree of agreement with histologic biopsy or the MRI-PDFF biomarker.