Hepatobiliscintigraphy

Hepatobiliary scintigraphy is a functional and morphological method designed to study the bile-forming and bile-excreting functions of the liver. On a series of scintigrams produced at intervals of 2-5 minutes immediately after intravenous administration of the radiopharmaceutical, 10-12 minutes after the appearance of the liver image, the bile ducts begin to be visualized, and a little later, after 3-4 minutes, the image of the gallbladder appears. In healthy people, the maximum radioactivity above the liver is recorded after about 12 minutes. By this time, the radioactivity curve reaches its maximum. Then it acquires the character of a plateau: during this period, the rate of capture and excretion of the radiopharmaceutical by hepatocytes balance each other. As the radiopharmaceutical is excreted with bile, the radioactivity of the liver decreases (by 50% in 30 minutes), and the intensity of radiation above the gallbladder begins to increase. In order to force the excretion of the radiopharmaceutical with bile into the intestine, the patient is given a fatty breakfast. After this, the emptying of the bladder is significantly accelerated, its image on scintigrams begins to progressively decrease, and increasing radioactivity is recorded above the intestine. The patency of the bile ducts can be assessed in the same way.

By selecting several "areas of interest" on scintigrams (liver, gall bladder, bile ducts, intestines), it is possible to plot curves on the computer that reflect the passage of the radiopharmaceutical through the liver - bile ducts - gall bladder - intestines system. Based on the analysis of these curves, it is possible to study the functional parameters of this system.

Hepatobiliary scintigraphy is indicated for all disorders of the biliary system: cholestasis of various origins, dyskinesia, developmental anomalies (for example, agenesis of the bile ducts in children), the presence of pathological anastomoses, etc. At the same time, this method allows one to obtain an idea of the detoxifying function of the liver.

In hepatoscintigraphy, as in hepatobiliary scintigraphy, after intravenous administration of the corresponding radiopharmaceutical, a series of liver images is obtained at intervals of several minutes. The first scintigrams are used to judge the vascularization of the organ, the subsequent ones - the functional activity of stellate reticuloendotheliocytes, but most importantly - the topography and macrostructure of the organ (position, shape, size, presence of focal formations). Of course, colloidal particles are captured from the blood by reticuloendotheliocytes not only in the liver, but also in the spleen and bone marrow. Normally, the liver captures approximately 90% of the administered radiopharmaceutical, therefore only its image is present on the scintigrams. In case of liver damage, along with the image of the liver (which is always weakened), an image of the spleen appears on the scintigrams, and in some cases, the bone marrow. Thus, this symptom - the appearance of the spleen and bone marrow on scintigrams serves as an indirect sign of liver function insufficiency. The main indication for hepatoscintigraphy is to obtain an approximate functional-topographic characteristic of the liver, which is necessary when examining patients with hepatitis, cirrhosis, and focal liver lesions of various origins.

The above information shows the wide range of possibilities available to a specialist in the field of radiology in examining the liver and biliary tract. However, this is not all. According to indications, a radiopaque examination of the vascular system of the liver is performed. By catheterization, a contrast agent is introduced into the celiac trunk, which extends from the abdominal aorta, and a series of angiograms are produced. Thanks to this method, an image of the entire celiac trunk system and its branches is obtained - a celiacogram. It depicts the left gastric and splenic arteries, the common hepatic artery, the gastroduodenal artery extending from it, the proper hepatic artery and its branches in the liver. In the final phase of celiacography, the contrast agent, having passed through the arteries and capillary network, appears in the veins and gives an image of the splenic and gastric veins on the pictures, and, finally, the portal vein - recurrent splenoportography. It should be noted that when conducting an X-ray examination of the arterial vessels of the abdominal cavity, preference is given to digital methods of image registration - digital subtraction angiography. This allows one to get rid of interfering shadows of the spine and abdominal organs and obtain higher quality angiograms.

There are methods of direct contrasting of the portal vein. For this, the contrast agent is injected through a puncture of the skin into the pulp of the spleen near its gates, from where the contrast agent enters the portal vein - splenoportography. They also perform a percutaneous (transparietal) puncture of one of the branches of the portal vein in the liver and retrogradely fill the main trunk of the portal vein - percutaneous transhepatic portography.

The diameter of the portal vein is 14-16 cm. The shadow of the lienoportal trunk is intense, uniform, and has smooth contours. The intrahepatic portal system is a rich network of vessels. To the periphery, the lumen of the veins gradually narrows. In order to examine the trunks of the right, median, and left hepatic veins, they are catheterized from the inferior vena cava with subsequent serial angiography.

An important instrumental non-invasive method for studying blood flow in the liver and the vessels that provide its vital functions (hepatic artery, splenic, portal and hepatic veins, inferior vena cava) is Dopplerography, especially color Doppler mapping.

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