In a large retrospective study, ultrasound’s sensitivity was 89% and specificity was 81%.

Many clinicians order hepatic ultrasound to screen for steatosis in patients with suspected nonalcoholic fatty liver disease (NAFLD). However, a recent ‘practice guidance’ document from the American Association for the Study of Liver Diseases concludes that ultrasound ‘is not recommended as a tool to identify hepatic steatosis due to low sensitivity’ (NEJM JW Gen Med Jun 15 2023 and Hepatology 2023; 77: 1797-1835). Because the case against using ultrasound for this purpose is based on relatively old data, researchers have conducted this more-contemporary observational study – arguing that newer ultrasound transducers are more sensitive for detecting steatosis.

The study included 5000 patients with suspected liver disease at six centres in Korea, Japan and the USA. All patients underwent both B-mode ultrasonography and magnetic resonance proton density fat fraction (MRI-PDFF) between 2015 and 2021; because MRI-PDFF compares favourably with liver biopsy for identifying steatosis, it was the standard to which ultrasound was compared. The sensitivity and specificity of ultrasound for identifying any degree of steatosis were 89% and 81%, respectively. For detecting mild steatosis, sensitivity and specificity were 83% and 81%, respectively. Variability in accuracy across the six study centres was minimal. Overall, about 40% of patients had steatosis, most commonly related to NAFLD, alcohol use and chronic viral hepatitis.

Comment: These results suggest that ultrasound remains a reasonable noninvasive tool for detecting hepatic steatosis. It is not perfect, but it can help clinicians diagnose NAFLD
in patients with mildly elevated transaminases and metabolic risk factors.

Allan S. Brett, MD, Clinical Professor of Medicine,
University of Colorado School of Medicine, Aurora, USA.

Lee CM, et al. A reappraisal of the diagnostic performance of B-mode ultrasonography for mild liver steatosis. Am J Gastroenterol 2023; 118: 840-847.

This summary is taken from the following Journal Watch titles: General Medicine, Gastroenterology, Ambulatory Medicine.