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US signs of normal liver
Last reviewed: 19.10.2021
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Normal liver parenchyma looks like a homogeneous structure interrupted by the portal vein and its branches, which are visualized as tubular linear structures with echogenic walls. Thin hepatic veins are anechogenous. In a normal liver, hepatic veins can be traced all over before they merge with the inferior vena cava. Hepatic veins dilate when carrying out a Valsalva test (a formed exhalation with a closed mouth and nose). The lower hollow vein is visualized in the liver and can vary depending on the respiratory cycle. The aorta is defined as a pulsating structure behind and medial to the liver.
The crescent ligament slit is defined as the structure of increased echogenicity slightly to the right of the median line in the transverse section.
In addition to the right and left lobes of the liver, it is necessary to recognize the caudate lobe bordered by a posterior inferior vena cava and separated from the front and top of the left lobe by a hyperechoic line. From below, the caudate lobe is limited to the proximal part of the left portal vein. It is necessary to be able to identify the caudate fraction, because it can be mistaken for a tumor.
The gallbladder and the right kidney should also be recognized. The gallbladder is visualized on the longitudinal sections as an anechogenous, pear-shaped formation.
It is necessary to identify the spine and pancreas.
Echogenicity of the normal liver is the average between the echogenicity of the pancreas (which is more echogenic) and the echogenicity of the spleen (which is less echogenic).