The objective of this study is: (1) to compare the feasibility (technical successes rate and reliability) in measuring attenuation coefficient between two different frequencies (3MHz, 4MHz) of ultrasound beam; (2) to evaluate and compare the diagnostic performance of attenuation coefficient for steatosis using two different frequencies (3MHz, 4MHz) of ultrasound beam by comparison with the pathologic results acquired by liver biopsy or surgery.

Investigators measure the distance between the skin and liver capsule on B-mod images.

Investigators place a region of interest (ROI) avoiding reverberation artifacts and acquire attenuation coefficient for five times.

For participants who require a liver biopsy, investigators try to target the same area in the liver, where ROI was placed.

Investigators evaluate hepatic steatosis, lobular inflammation, and fibrosis of tissue of the liver using a scoring system suggested by Nonalcoholic Steatohepatitis Clinical Research Network.

Inclusion Criteria:

• Participants who are candidates for liver donation and scheduled liver biopsies for assessment of hepatic steatosis
• Participants suspected of nonalcoholic fatty liver disease and scheduled for liver biopsy or surgery

Exclusion Criteria:

• Participants with a BMI of less than 23
• Participants underwent liver transplantation or right hepatectomy
• Participants who have a large mass in the right liver
• Participants who have a bleeding tendency (platelet count < 80000, prothrombin time and international normalized ratio > 1.5)

Participants at risk of fatty liver disease

No plan to share data with another researcher