Methods of ultrasound of the liver

The technique of performing ultrasound of the liver differs from the specificity of conducting the echography of other organs with only some diagnostic nuances in the process of interpreting the results obtained. As a rule, the study of the liver is part of a general ultrasound examination of the abdominal cavity organs. Ultrasound is carried out according to the indications at any time, the procedure does not require special preparatory measures - cleansing, diets and so on. It should be noted that, together with the study of the liver, ultrasound of the organs of the upper part of the peritoneum (gall bladder) is often carried out. If the diagnosis is complex, care should be taken to ensure that the gallbladder is stretched, and the collar vein is reduced to those that it has at rest. This is achieved by eight hours of starvation.

The technique of ultrasound of the liver involves the examination of the organ in three adjacent planes. The longitudinal zone is sequentially studied, and also the transverse and oblique. The zonal location of the organ, the sharpness or blurriness of the contours, the size is estimated. The structure and the reflecting capacity of the parenchyma-echogenicity-are subjected to compulsory research. Also, the condition of the vessels and the vascular pattern itself, the ducts, are analyzed. If a patient is prescribed treatment, the echogram is performed in the planned mode repeatedly, thus, its diagnostic accuracy increases.

The main tasks that the echography of the liver solves: 

• Identification of echographic signs of hepatitis, cirrhosis, portal hypertension; 
• Assessment, including cito, vein blockages, exclusion of extrahepatic portal hypertension, thrombosis of veins; 
• Assessment of the disorder or stability of hemodynamics.

The procedure for performing ultrasound of the liver is standard, although it depends on the specifics of the study. The rules of positioning the patient during the procedure are quite simple. The beginning of the study assumes that the patient lies on his back, then he turns over to the left side so that the right lobe, the liver region, is better visualized. A variant of the examination is when the patient is semi-exposed, or scanning from the back (with ascites). Specialist, conducting ultrasound. You can ask the patient to raise his right hand and place a palm under the back of his head. This helps to expand the intercostal space and improve the contact of the scanner. Change of positions is necessary for a detailed and complete review of all the investigated parameters of liver status. Visualization is carried out by special frequency sensors (3-5 MHz). Sensors come in a variety of sizes and are used depending on the body weight of the patient, as well as the frequency of the sensors. The maximum frequency allows the signal to penetrate much deeper through the fatty interlayer of the patient's peritoneum. Smaller frequencies are used when the left region of the liver is scanned - it is less than the right one. Linear (with flat surface) sensors can be curved, they are also called "hockey sticks", they are also good for examining the left region of the liver. On the right side, a subcostal (epigastric zone) is used. The intercostal area, which is anatomically difficult to access, is investigated by a sensor with a low beam frequency, sectoral. The modern technique of ultrasound of the liver includes dopplerography. This method, like ultrasound, is based on the reflection of signals, but the reflection comes from the object under investigation in motion - from the blood, more precisely its elemental elements. The frequency of the signal sent is directly related to the speed of the blood flow. For the Doppler mode, specific high-sensitivity sensors are used.

Ultrasound of the liver, as a rule, gives more precise results, if it is carried out on inspiration, respiratory arrest of the patient. Then the liver is forced to descend, and its visual examination becomes more accessible. Techniques for carrying out the echogram correspond to the approved rules and include the keeping of the sensor by a longitudinal line from the midline, and there is also a transverse movement - towards the navel. Used and diagonal "oblique" movement - the sensor is placed at an angle parallel to the right edge and move it diagonally, cranial way (up, kranion - head), then down. In addition, there is a sagittal (division on the right and left side) way of movement of the sensor, which helps to determine the size of the length of the organ, and is also designed for the echogram of the bile duct, the vascular system (portal vein, aorta and inferior vena cava).

Stages of ultrasound examination of the liver: 

1. Gray scale mode when the front dimension is explored in conjunction with the posterior alternately right and then left lobe. The capsule, contours, structural echogenicity of a liver, veins, ducts, including the largest - holedoh is estimated. A lumen of the umbilical vein is revealed - paraumbillic. The patient lies on the back, then turns over to the left side to examine the longitudinal zone of the right rib and intercostal space. Change of positions is necessary for obtaining a more detailed diagnostic picture.
2. DCS mode. The patency of the venous-vascular system of the liver is assessed. For this, it is better to use a mode that assumes color Doppler coding (CDC), as well as spectral analysis. Dopplerography makes it possible to specify the state of the circulatory system of the liver and its orientation. Such an angiography helps to assess the blood flow in the umbilical vein most accurately, and also the blood flow (reverse) in the most important for the liver - portal vein is determined by the DCC.
3. Obtaining quantitative information, parameters of the hemodynamic system. The study is performed with the help of intercostal (intercostal) access or with the help of the subcostal (right side of the epigastrium) access. The specialist ensures that ultrasound is as closely as possible combined with the longitudinal direction of the vessel. Scanning of the intrahepatic zone of the main part of the collar vein - the trunk is performed with the help of intercostal access (intercostal). Although the visual display of hepatic large veins in any case is obtained qualitative, regardless of the type of access. 
4. It is recommended to complete the ultrasound examination by studying the size and structure of the nearby spleen. The patient can lie on the right side, if the spleen is high, then the sitting position is possible.

The technique of ultrasound of the liver is constantly being improved and adjusted depending on the appearance of new technologies, the creation of more highly accurate diagnostic equipment and sensors.

[1], [2], [3], [4], [5]