Methodology of liver ultrasound

The technique for performing an ultrasound of the liver differs from the specifics of performing echography of other organs only by some diagnostic nuances in the process of interpreting the results. As a rule, a liver examination is part of a general ultrasound examination of the abdominal organs. Ultrasound is performed according to indications at any time, the procedure does not require special preparatory measures - cleansing, diets, etc. It should be noted that along with the liver examination, an ultrasound of the organs of the upper part of the peritoneum (gall bladder) is often performed. If the diagnosis is complex, care should be taken to ensure that the gall bladder is stretched, and the collar vein is reduced to the size that it has at rest. This is achieved by fasting for eight hours.

The technique of conducting ultrasound of the liver involves examining the organ in three adjacent planes. The longitudinal zone, as well as the transverse and oblique ones, are studied sequentially. The zonal location of the organ, the clarity or blurriness of the contours, and the size are assessed. The structure and reflectivity of the parenchyma - echogenicity - are subject to mandatory examination. The condition of the vessels and the vascular pattern itself, ducts are also analyzed. If the patient is prescribed treatment, the echogram is performed in the planned mode repeatedly, thus increasing its diagnostic accuracy.

The main tasks that liver echography solves:

• Detection of echographic signs of hepatitis, cirrhosis, portal hypertension;
• Evaluation, including cito, venous occlusion, exclusion of extrahepatic portal hypertension, venous thrombosis;
• Evaluation of hemodynamic disturbance or stability.

The technique for performing an ultrasound of the liver is standard, although it depends on the specifics of the study. The rules for 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 on his left side so that the right lobe, the liver area, is better visualized. An examination option is when the patient is reclining, or scanning from the back (in case of ascites). The specialist performing the ultrasound. May ask the patient to raise his right hand up and put his palm under the back of his head. This helps to expand the intercostal space and improve the scanner contact. Changing positions is necessary for a detailed and complete view of all the examined parameters of the liver condition. Visualization is carried out by special frequency sensors (3-5 MHz). Sensors come in different sizes and are used depending on the patient's body weight, as well as the frequency of the sensors. The maximum frequency allows the signal to penetrate much deeper through the patient's peritoneal fat layer. Lower frequencies are used when scanning the left area of the liver - it is smaller than the right one. Linear (flat surface) sensors can be curved, they are also called "hockey sticks", they are also good for examining the left side of the liver. On the right side, subcostal (epigastric zone) access is used. The intercostal zone, which is anatomically difficult to access, is examined with a sensor with a low beam frequency - a sector one. Modern methods of conducting liver ultrasound include Dopplerography. This method, like ultrasound, is based on the reflection of signals, but the reflection comes from the object being examined in motion - from the blood, or rather its formed elements. The frequency of the signal sent is directly related to the speed of blood movement. Specific highly sensitive sensors are used for the Doppler mode.

Liver ultrasound, as a rule, gives clearer results if it is performed on inhalation, holding the patient's breath. Then the liver is forced to descend, and its visual examination becomes more accessible. The techniques for conducting an echogram correspond to the approved rules and include moving the sensor in a longitudinal line from the midline, there is also a transverse movement - in the direction of the navel. A diagonal "oblique" movement is also used - the sensor is placed at an angle parallel to the right rib and moved diagonally, cranially (up, kranion - head), then down. In addition, there is a sagittal (dividing into right and left sides) method of moving the sensor, which helps to determine the length of the organ, and is also intended for an echogram of the bile duct, vascular system (portal vein, aorta and inferior vena cava).

Stages of an ultrasound examination of the liver:

1. Gray scale mode, when the anterior dimension is examined together with the posterior one, alternately of the right and then the left lobe. The capsule, contours, structural echogenicity of the liver, veins, ducts, including the largest one - the common bile duct, are assessed. The lumen of the umbilical vein - paraumbilical - is revealed. The patient lies on his back, then turns over to the left side to examine the longitudinal zone of the right rib and intercostal space. Changing positions is necessary to obtain a more detailed diagnostic picture.
2. Color Doppler mode. The patency of the liver venous-vascular system is assessed. For this, it is better to use a mode that involves color Doppler coding (CDC), as well as spectral analysis. Dopplerography allows you to specify the state of the liver circulatory system and its direction. Such angiography helps to assess the blood flow in the umbilical vein most accurately, and with the help of CDC, the blood flow (reverse) in the most important for the liver - the portal vein - is determined.
3. Obtaining quantitative information, parameters of the hemodynamic system. The study is carried out using intercostal (intercostal) access or subcostal (right side of the epigastrium) access. The specialist ensures that the ultrasound is as closely aligned as possible with the longitudinal direction of the vessel. Scanning of the intrahepatic zone of the main part of the collar vein - the trunk is carried out using intercostal (intercostal) access. Although the visual display of the large hepatic veins is in any case of high quality, regardless of the type of access.
4. It is recommended to finish the ultrasound examination by examining the size and structure of the nearby spleen. The patient can lie on the right side, if the spleen is located high, then a sitting position is possible.

The technique for performing ultrasound examination of the liver is constantly being improved and adjusted depending on the emergence of new technologies and the creation of more precise diagnostic equipment and sensors.

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