The exploration by means of imaging tests of patients in whom a disease in the upper abdomen is suspected, due to symptoms or analytical, should begin with an ultrasound.
It is important to know that each viscus, like other structures of the abdomen, has its own echogenicity that depends mainly on its composition and internal anatomical structure. Echogenicity is the brightness of the viscus image on the ultrasound screen once properly calibrated and is related to the reflection of ultrasound in the visceral tissue. The greater the reflection, the greater the echogenicity and, therefore, the greater the brightness, and the lower the reflection, the lower the echogenicity and the lower the brightness. The radiologist, by his experience, knows the normal echogenicity of the different viscera and the comparison between nearby organs helps him to assess it adequately. When the echogenicity of the organ increases or decreases with respect to normality, it is said that there is hyperechogenicity or hypoechogenicity respectively.
Located in the upper right area of the abdomen (right hypochondrium), it is affected in a large number of diseases and pathological processes. Depending on the degree of extension. a distinction is made between diffuse involvement (generalized to all or almost the entire liver) and focal involvement, which can be single or multiple (only one part or several are affected, being the rest normal).
Diffuse involvement. It manifests with both hyper and hypoechogenicity. Hyperechogenicity is frequent in diseases that produce deposits of substances that, even being in the liver under normal conditions, accumulate in excess. In steatosis there is an excess of fat; in cirrhosis and chronic hepatitis, excess of fibrous tissue; in hemochromatosis, excess of iron; in glycogen storage disease type I, excess of this substance and also of fat. In other cases, the liver is infiltrated with neoplastic or granulomatous material. In addition, some of these diseases, especially when they become chronic, may produce alteration of the liver or ecotexture, modification of the contour of the liver, as well as increase or decrease in its size.
Generalized hypoechogenicity is rare. Sometimes, although rarely, it appears in acute hepatitis, whatever its cause. It can also be due to malignant diffuse infiltration such as lymphoma or metastatic infiltration.
Focal impairment. In this type of affectation, the echogenicity of the liver is not altered except where the abnormality appears, termed Space Occupying Lesion (SOL), which can be single or multiple. There may be isoechogenic, hypoechoic or hyperechoic SOLs (same, less or greater echogenicity than the adjacent liver). The ability of ultrasound to detect SOLs depends on the size and echogenicity of the lesion. As bigger, as easier it is to detect it. The echogenicity of the SOL is very important in the visibility of the same, thus, small lesions of 1-2 cm very hypoechoic, such as simple cysts, or hyperechoic, such as hepatic hemangiomas, can be perfectly visible; however, isoechogenic SOLs generally require a larger size to be detectable with this technique.
The number of pathological processes manifested as single or multiple SOLs is enormous and of a very varied nature: benign, such as hemangioma, simple cyst, focal nodular hyperplasia, adenoma; malignant, such as hepatocarcinoma, angiosarcoma, metastasis, etc; infectious, such as liver abscess; parasitic, such as hydatid cyst; traumatic, like the bruise.