The purpose of this study is to assess UDFF performance (compared to MRI)

Inclusion Criteria:

• All patients who had hepatic ultrasound with available UDFF measurements and hepatic MRI (with steatosis quantification sequences) between 01/01/2022 and 31/09/2023 may be included.

Exclusion Criteria:

• chronic liver disease with a different etiology other than NAFL/NASH or mixed (hepatitis B or C, hemochromatosis, autoimmune hepatitis, Wilson's disease, cholestasic disease, alpha 1 antitrypsin deficiency),
• decompensated cirrhosis (ascites, jaundice, encephalopathy, rupture of esophageal varices),
• hepatocellular carcinoma.
• opposition to the use of its data

patients followed by the department of hepato gastroenterology of the CHU d'Angers for liver disease (NAFLD)