2026 Volume 67 Issue 2 Pages 87-100
Metabolic dysfunction-associated steatotic liver disease (MASLD) affects an estimated 25%-30% of the global population, and its prevalence continues to increase. Accurate liver fat quantification is essential for monitoring treatment response, assessing prognosis, and evaluating risks for cardiovascular disease and diabetes mellitus. Magnetic resonance imaging-based proton density fat fraction (MRI-PDFF) has become the new reference standard, replacing invasive liver biopsy. Although conventional B-mode ultrasound remains widely accessible, it is limited by operator dependence and low sensitivity for mild steatosis. Recent developments in ultrasound attenuation technologies now allow objective fat quantification. In Japan, four methods-controlled attenuation parameter, ultrasound-guided attenuation parameter, improved attenuation, and attenuation imaging-have been validated in multicenter studies. Among these approaches, B-mode-guided techniques demonstrate stronger correlations with MRI-PDFF, improved diagnostic accuracy, and reduced influence from body habitus compared with one-dimensional measurements. Combining multiple acoustic parameters beyond attenuation coefficient may further enhance performance. Standardization will require unified acquisition protocols and clarification of confounding factors.
