Liver Ultrasound Characteristics and Diagnostic Criteria

Echogenicity and Texture

Normal liver parenchyma shows echogenicity similar to or just higher than normal renal cortex, according to the American College of Radiology 1, 2
Intrahepatic vessels and portal veins should be clearly visible, as recommended by the American College of Radiology 2
The diaphragm should be clearly defined, as stated by the American College of Radiology 1, 2

Vessels should traverse through the liver parenchyma without distortion, as noted in Clinical and Molecular Hepatology 3

Increased echogenicity compared to renal cortex is indicative of fatty liver (steatosis), with a sensitivity of 84.8% and specificity of 93.6% for moderate to severe hepatic fat deposition, according to the American College of Radiology 1, 2
Fatty liver can be graded as mild, moderate, or severe based on the degree of echogenicity increase and visualization of diaphragm and intrahepatic vessel walls, as described by the American College of Radiology 2
Ultrasound has a sensitivity of 65-95% for detection of cirrhosis, with a positive predictive value of 98%, as reported by the American College of Radiology 4
A nodular liver surface, especially on the undersurface, has a sensitivity of 86% for detecting cirrhosis, according to the American College of Radiology 4

Ultrasound is recommended as the initial diagnostic test of choice in patients with suspected liver disease, as suggested by the American College of Radiology 4
Normal liver ultrasound has a high negative predictive value (91.5-95%) for excluding significant liver pathology, according to the American College of Radiology 4
Comparison with kidney echogenicity (hepatorenal index) provides a more objective assessment of liver echogenicity, as noted by the American College of Radiology 1, 2
Fatty liver can mask underlying focal lesions due to increased background echogenicity, as warned by the American College of Radiology 1
Technical factors such as gain settings can artificially alter the apparent echogenicity, as cautioned by the American College of Radiology 2