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

Area of Science:

• Radiology
• Hepatology
• Medical Imaging Analysis

Background:

• Metabolic dysfunction-associated steatotic liver disease (MASLD) diagnosis requires accurate liver fat quantification.
• Ultrasound's attenuation coefficient (AC) is a readily available but unstandardized measure of liver steatosis.
• Magnetic resonance imaging-proton density fat fraction (MRI-PDFF) is a precise but less accessible reference standard.

Purpose of the Study:

• To develop and validate models for converting ultrasound AC into a percentage-like index for MASLD assessment.
• To compare the diagnostic performance of these novel models against MRI-PDFF for grading liver steatosis.

Main Methods:

• Retrospective study of 199 patients with suspected MASLD undergoing ultrasound (AC) and MRI (PDFF).
• Development of two models: PDFF conversion fraction (PCF) using MRI-PDFF as reference, and attenuation level fraction (ALF) converting AC values (0.5-1.0 dB/cm/MHz) into percentages.
• Area under the receiver operating characteristic curve (AUC) analysis to evaluate diagnostic performance for mild (≥S1), moderate (≥S2), and severe (≥S3) steatosis.

Main Results:

• Both PCF and ALF models demonstrated high diagnostic accuracies (AUCs 0.93 and 0.87, respectively) in grading liver steatosis compared to MRI-PDFF.
• The PDFF conversion fraction (PCF) showed a slightly higher AUC (0.93) than the attenuation level fraction (ALF) (0.87).
• Significant differences in PDFF values were observed between liver segments, highlighting steatosis heterogeneity.

Conclusions:

• The developed PCF and ALF models offer reliable methods for quantifying liver steatosis from ultrasound AC.
• The attenuation level fraction (ALF) is considered a more objective parameter for grading liver steatosis due to its consideration of AC value ranges and liver heterogeneity.
• These models could improve non-invasive MASLD diagnosis and monitoring using widely available ultrasound technology.