11.1. LIVER
11.1.1. Radiological anatomy in normal condition
The liver is the biggest glandule in the human body; its mass is on the average 1.5 kg in men and 1.2 kg in women. According to some sources the liver has 500 different functions (among which are detoxification, enzymatic, excretory, participation in the processes of energy metabolism, etc.). When examining the patient, it is extremely important to study both the morphological structure and the functional state of the liver. Modern techniques of radiology can solve both these problems. However, before proceeding directly to the techniques of diagnostic radiology, it is necessary to have a clear picture of the anatomical and physiological structure of the body.
The liver is located in the right subdiaphragmatic region of the abdominal cavity and is attached by the ligaments to the diaphragm, abdominal wall, stomach and intestines.
The structural-functional unit of the organ is the liver acinus, which has the shape of a hexagonal prism with a diameter of 1-1.5 mm and a height of 1.5-2 mm. The liver acinus is formed by hepatocytes (85% of all liver cells), which are located around the central vein. There are about 500 thousand acini in the liver. (Fig. 11.1).
With the development of surgery, the division of the liver into larger units has become more and more important. Currently, the liver is divided into 2 lobes (larger right and smaller left), which, in turn, are divided into 8 segments (4 in each lobe). The 1st segment is also called the caudate lobe of the liver, and the 4th is the quadrate lobe. The basis of this division (scheme of Couinaud, 1957) was the branching of the portal vein, which is divided in the portal fissure into the right and left branches, then gives the branches of the 2nd order (Fig. 11.2). The areas, in which the veins of the 2nd order are branching out, as well as the hepatic artery and bile ducts, are called liver segments.