X-ray of the liver and biliary tract

The liver is one of the most complex organs in its structure and functions, is the largest gland in the body, takes part in the processes of digestion, metabolism and blood circulation, performs specific enzymatic and excretory functions. With the help of various research techniques, doctors have learned to objectively evaluate the morphology of the liver and understand its multifaceted functions. Among these techniques, radiation methods have taken a worthy place. This also applies entirely to the study of the bile ducts and pancreas. Here, radiation diagnostics has, without exaggeration, won a leading position, but on the condition that it is considered as an integral part of the general diagnostic scheme.

Indications for X-ray of the liver and bile ducts

Indications for radiographic examination (X-ray) of the liver and bile ducts are determined by the clinician based on the anamnesis and clinical picture of the disease. The choice of the method of radiographic examination is made jointly by the clinician and the radiologist. The latter draws up a plan of the examination, analyzes its results and formulates a conclusion.

X-ray examination of the liver and bile ducts

The liver consists of two lobes, which are usually divided into 8 segments. Each segment contains a branch of the portal vein and a branch of the hepatic artery, and the bile duct exits the segment. Segments I and II make up the left lobe of the liver, and III-VIII - the right. The main cellular mass of the liver - about 85% of all cells - is formed by hepatocytes. They are collected in lobules, of which there are about 500,000 in the liver. Hepatocytes in the lobules are located in rows along the bile capillaries and the smallest venous branches. The walls of the latter consist of stellate reticuloendotheliocytes - Kupffer cells, they make up 15% of all liver cells.

The hepatic circulatory system includes two inflowing blood vessels: the portal vein, through which 70-80% of the total volume of inflowing blood enters, and the hepatic artery, which accounts for 20-30%. Blood outflow from the liver occurs through the hepatic veins, which go into the inferior vena cava, and lymph outflow occurs through the lymphatic pathways.

On plain radiographs, the liver produces an intense, uniform shadow of approximately triangular shape. Its upper contour coincides with the image of the diaphragm, the outer one stands out against the background of extraperitoneal fatty tissue, and the lower one corresponds to the anterior edge and is outlined against the background of other abdominal organs. A normal gallbladder is rarely visible on conventional images and then mainly in the area of the fundus.

During ultrasound examination, the image of the liver of a healthy person is quite homogeneous, with a fine-grained echostructure caused by elements of the stroma, vessels, bile ducts and ligaments. The border between the right and left lobes of the liver is an oval hyperechoic formation - a reflection of the round ligament of the liver.

In the region of the liver gate, thin-walled tubular formations are determined. These are primarily the portal vein with its relatively thick walls and a main trunk caliber of 1-1.2 cm, the hepatic arteries, and also the common bile duct with a diameter of about 0.7 cm. Inside the liver, the arteries and bile ducts are not noticeable, but echo-negative stripes of venous vessels are clearly outlined. The hepatic veins heading toward the inferior vena cava are especially clearly visible.

On sonograms, the gallbladder is clearly visible as a homogeneous, echo-negative, oval-shaped formation with smooth edges. Its dimensions vary widely - from 6 to 12 cm in length and from 2.5 to 4 cm in width. The thickness of the gallbladder wall in the fundus and body is 2 mm, in the funnel and neck - 3 mm.

The image of the liver on CT scans depends on the level of the layer being isolated. If you go from above, then at the level of ThIX-ThX, a shadow of the right lobe appears, and at the level of ThX-ThXI - and the left lobe. On subsequent sections, a homogeneous structure of the liver with a density of 50-70 HU is detected. The contours of the liver are smooth and sharp. Images of vessels can be determined against the background of the liver tissue; the density of their shadow is lower (30-50 HU). The gates of the liver are clearly visible, at the posterior edge of which the portal vein is determined, and in front of and to the right of it - the common bile duct (normally it is indistinctly drawn). At the level of ThXI-ThXII, an image of the gallbladder is noted. On spiral tomographs, it is possible to examine the vascular system of the liver. For this purpose, tomography is performed with the patient's breath held after the introduction of a bolus of a water-soluble contrast agent into the venous bed.

The capabilities of magnetic resonance imaging of the liver are similar to those of CT, but MRI can produce an image of the layers of the liver in all planes. In addition, by varying the technique of magnetic resonance imaging, it is possible to obtain an image of the liver vessels (MR angiography), bile ducts and pancreatic ducts.

A number of methods for artificial contrasting have been developed for X-ray examination of the gallbladder and bile ducts. They are divided into three groups:

1. Cholecystography.
2. Cholegraphy.
3. Cholangiography / Hepatobiliary scintigraphy

Of the radiographic examination methods, the most noteworthy are angiographic methods and studies with the introduction of a contrast agent into the bile and pancreatic ducts. These methods are of great importance for the differential diagnosis of liver cirrhosis, biliary atresia, portal hypertension, and the recognition of a volumetric process in the liver and bile ducts. Based on the results of these studies, patients are selected for surgical treatment.

The method of contrasting the esophagus with barium to detect varicose veins is currently used less and less, since endoscopic examination gives much better results. Plain abdominal X-ray is also losing its clinical significance for diagnosing liver diseases.

Angiography of the liver

Liver angiography has acquired greater clinical significance with the introduction of selective angiography of the visceral branches of the abdominal aorta. Among the angiographic methods, the most common are celiac and mesentericography. Angiography is used to identify the pathological process and clarify its features, as well as to decide on surgical treatment. The method is used to diagnose focal liver lesions, recognize tumors, parasitic diseases, malformations and vascular pathology in this area. The method is contraindicated in severe patient conditions, acute infectious diseases, mental disorders, and hypersensitivity to iodine preparations.

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Splenoportography

Splenoportographic examination involves the introduction of a contrast agent into the spleen followed by radiography. The radiograph clearly outlines the portal and splenic vein system, which allows identifying portal circulation disorders, the presence of collaterals, and even focal lesions of the liver and spleen. Indications for splenoportography include splenomegaly, hepatomegaly, and gastric bleeding of unknown etiology. In the presence of portal hypertension, there is an expansion of the entire splenic and portal vein system, deformation of the vascular pattern of the liver with areas of thrombosis, and the presence of collateral blood flow.

To clarify the origin of portal hypertension, a splenoportocholangiographic study can be used. Its essence lies in the fact that contrast agents easily secreted by the liver (bilignost, etc.) are introduced into the spleen. This method allows not only to assess the state of portal blood circulation, but also to determine the patency of the bile ducts.

Hepatovenography

In addition, hepatovenography (liver phlebography) is used in clinical practice. The method is used to diagnose Badz-Chiari syndrome, to clarify the state of the outflow from the liver before shunting surgery in patients with liver cirrhosis.

Direct portography

Direct portography (ileomesentericoportography) is most widely used in surgical practice to clarify the causes and degree of portal circulation disorder: the state of the extra- and intrahepatic portal bed, the presence of collaterals that are not contrasted during sllenoporography. Direct portography in combination with other special research methods allows determining the scope of surgical intervention. Direct portography is especially important for patients with portal hypertension syndrome after surgery, when it is necessary to decide on the imposition of a mesenteric-caval anastomosis. Mesenteric vessels are most often used for research.

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Cholecystocholangiography

Oral and intravenous cholecystocholangiography in acute diseases is uninformative, since the affected hepatocytes weakly excrete contrast agents into the bile. These examination methods give better results in the recovery period of viral hepatitis, in isolated pathology of the biliary tract, and in chronic hepatitis.

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Pancreatocholangiography

Endoscopic retrograde cholangiopancreatography (ERCP) is used when other methods fail to establish the cause of cholestasis. Preliminary diagnostics include a thorough anamnesis, examination of the patient, ultrasound and/or CT, and, if possible, intravenous contrast. Endoscopic retrograde cholangiopancreatography is of great importance in recognizing diseases of the pancreas and biliary tract. The examination includes fibroduodenoscopy, cannulation of the large duodenal papilla with a catheter, administration of a contrast agent (verografin) into the bile and pancreatic ducts, and X-ray contrast examination. The method is used to diagnose choledocholithiasis, tumors of the intra- and extrahepatic bile ducts, pericholedochal lymphadenitis, and pancreatic cancer.

In addition, in case of combined liver and biliary tract lesions, transhepatic (transparietal) cholangiography can be used for differential diagnostics of mechanical and hepatocellular jaundice. This involves introducing a contrast agent into the intrahepatic bile ducts by means of a liver puncture biopsy. Since the biliary tract is well contrasted on the radiograph, it is possible to determine the localization of obstruction and the genesis of cholestasis. However, this method of examination is rarely used in children.