Fraction Conversion Models Based on Ultrasound Attenuation Coefficient for Assessing Liver Steatosis

Objectives: We aimed to develop models capable of converting the attenuation coefficient (AC) into a percentage-like index in patients with suspected metabolic dysfunction-associated steatotic liver disease (MASLD). Methods: In this retrospective, cross-sectional study, we consecutively enrolled participants with suspected MASLD from the Weight Loss Medical Centre who had undergone both ultrasound examinations that yielded AC results and magnetic resonance imaging (MRI) scans including proton density fat fraction (PDFF). The first model, defined as the PDFF conversion fraction (PCF), used the MRI-PDFF results as the reference standard. The other model, defined as the attenuation level fraction (ALF), converted AC values into percentages based on the range of AC values from 0.5 to 1.0 dB/cm/MHz. Area under the receiver operating characteristic curve (AUC) analysis was used to evaluate the diagnostic performance of the two models. Results: Among the 199 participants (mean age, 38.12 ± 9.56 years; 110 male), the PDFF values differed significantly among the different liver segments (p < 0.05). The PDFF values of the left liver and right liver were 12.6% and 16.1%, respectively. There was a significant difference between them (p < 0.05). The AUCs of the AC, PCF, and ALF were 0.92, 0.93, and 0.87, respectively, for detecting mild steatosis (≥ S1), moderate steatosis (≥S2), and severe steatosis (≥S3) when PDFF values ≥ 5%, ≥15%, and ≥25% were used as the reference standard, respectively. Conclusions: The two fraction conversion models (PCF and ALF) yielded good and identical diagnostic accuracies in grading liver steatosis. Considering the heterogeneous pattern of liver steatosis, the ALF was a more objective parameter.