The liver ultrasound is an integral part of the abdominal examination, which includes not only the liver itself, but also the gallbladder and bile ducts. What are the indications for a liver ultrasound? How to prepare for the test? How is the test performed? What does ultrasound of the liver detect?

Liver ultrasoundis an ultrasound examination of the liver, as well as the gallbladder and bile ducts. In some diseases, the liver ultrasound allows for the final diagnosis, e.g. in cholecystolithiasis and in acute cholecystitis. In addition, ultrasound is used in the diagnosis of the causes of jaundice, in the diagnosis of cirrhosis, portal hypertension and fatty liver parenchyma.

Liver ultrasound - ultrasound techniques and indications for the examination

Ultrasound examination of the liver, gallbladder and bile ducts is performed when liver cirrhosis is suspected, monitored or exacerbated, in hepatitis, in the diagnosis of jaundice, in people with suspected cholecystolithiasis, inflammation of the gallbladder, when cholelithiasis is suspected , in the search for metastatic foci in people with diagnosed cancer and in other conditions as an integral part of the ultrasound examination of the abdominal cavity during elective and emergency procedures.

Basic ultrasound of the liver uses classic grayscale (B-mode) imaging, vascular Doppler options (Color Doppler, Power Doppler and Spectral Doppler options) and other options to reduce the number of artifacts and improve the contrast of the obtained images e.g. harmonic imaging, spatially complex imaging.

In addition, there are new techniques used in the diagnosis of focal lesions in the liver:

  • ultrasound contrast media
  • elastography used to assess the degree of parenchymal fibrosis

Ultrasound of the liver using ultrasound contrast agents

High-class ultrasound scanners are used for examinations with the use of ultrasound contrast agents. Intravenous contrast is used, similar to other imaging techniques such as computed tomography or MRI. However, this contrast does make upgas microbubbles surrounded by a single phospholipid membrane, therefore it is safer, it does not burden the urinary system, therefore there are no contraindications for its use in people with renal insufficiency. The reported side effects include headache, injection site reaction and nausea.

This test significantly improves the sensitivity and specificity of classical ultrasonography in relation to the differential diagnosis of focal lesions in the liver, which are similar to computed tomography (CT) or magnetic resonance imaging (MR).

The indication for this test is the presence of a focal lesion in the liver, which is not a typical simple cyst - a lesion found quite often (it concerns about 2.5% of respondents). Also, in the case of a solid focal lesion with ultrasound morphology, as for an angioma with a maximum diameter of less than 3 cm in a patient with no history of neoplastic disease, a follow-up USG examination may be recommended in 3-6 months to assess the dynamics of changes. Otherwise, extended diagnostics is required.

Elastography

Currently, to assess the cohesiveness of the liver parenchyma, transient elastography (TE, FibroScan apparatus) is used to test the speed of mechanical wave propagation caused by a vibrating probe. It is a device dedicated exclusively to liver examination. Information from such a test is presented in the apparatus in the M - (Motion - one-dimensional presentation) presentation, and the final result is expressed as the value of Young's modulus in kPa.

In addition, in the classic ultrasound machines of some companies, SWE (Shear Wave Elastography) elastography was implemented to assess the degree of cohesiveness of the liver parenchyma. The obtained results can be presented in the form of a two-dimensional, color image, the so-called elastogram, in which the colors (red, green, blue) correspond to the deformation, either in a measurable form as the value of the speed of propagation of the transverse wave, or through the value of Young's modulus, expressed in m / s and kPa, respectively.

The indications for liver elastography examination include:

  • chronic hepatitis B, type C
  • nonalcoholic steatohepatitis (NASH)
  • alcoholic hepatitis (ASH)
  • primary biliary cirrhosis
  • primary sclerosing cholangitis
  • autoimmune hepatitis
  • storage hepatitis
  • toxic hepatitis
  • monitoring of liver transplant patients
  • elevated levels of liver enzymes ALT and AST of unknown cause

Liver ultrasound - how to prepare for the test?

The patient should prepare for the examination in the same way as for the examination of the abdominal cavity, Doppler aorta and iliac arteries, Doppler renal arteries, Doppler visceral arteries, that is:

  • should be fasting. If the test is in the afternoon, he should not eat or drink anything about 6-8 hours before the test
  • should not smoke, chew gum or, for example, a candy on the day of the examination
  • should maintain a proper diet for 2 days prior to testing, i.e. without bloating foods, such as cabbage, peas, beans, apples, grapes, and other stone fruit, or carbonated drinks. You can additionally give degassing agents, eg Espumisan, 3 days before the test day (2 tablets 3 times a day). No more tablets should be taken on the day of the examination. This does not apply when the test is performed in the emergency mode. Then the test is performed without preparation
  • regulating bowel movements is also important

Liver ultrasound - the course of the examination

Ultrasound examination of the liver should typically start a physical examination, i.e. an interview with the patient, which can be continued smoothly during the main part of the examination. It is important to know about previous imaging examinations: CT, MRI, including ultrasound of the abdominal cavity. If so, for what reason (is it the same as now or another - what?) And are the results of previous studies available to compare the dynamics of changes - especially if the study concerns the control of focal changes.

Technically, the ultrasound examination of the liver, gallbladder and bile ducts is performed in the supine position, on the left side (on the hip) and in an oblique position (on the hip with the body turned at an angle of approximately 45 degrees to the surface of the couch). As a standard, the examination is performed from under the right costal arch and from the intercostal access, obtaining a series of longitudinal, transverse and oblique sections. During the examination, a series of measurements of the liver itself and intrahepatic structures (intra and extrahepatic bile ducts, gallbladder, portal vein, hepatic veins, inferior vena cava) are performed to determine their size and the flow parameters in the portal vein and hepatic artery are measured. In addition, the shape of the liver, its outline, echogenicity and homogeneity of the parenchyma are assessed.

Liver ultrasound - test results

The study should end with a description with conclusions either marked in the text or at its end. The obtained images should be interpreted on the basis of the physical examination (interview), physical examination (palpation, sometimes deliberate compression of the transducer is also performed during the examination). In the case of control tests, it is important to assess the dynamics of changes based on the presented previous results with photos. The conclusions should include recommendations for further treatment - ultrasound checkup, verification in other CT / MRI imaging techniques or consultation with a family doctor or specialist.

Worth knowing

Liver ultrasound - pros and cons

The undoubted advantage of the study is its safety for both the examined and the researcher. It is also an advantage to be able to perform a physical examination before and / or during the examination. The advantage is also the possibility of selecting any number of sections and using other standard options that are in the camera - for example Doppler options.

What are the disadvantages of an ultrasound of the liver? The accuracy of this test depends on the operator's experience, the quality of the apparatus itself, but also on the test conditions. In addition, the translucency of the abdominal soft tissues also has a significant impact on the accuracy of the examination. Obese people, as a rule, but not always, are worse tested than lean people. Swelling of soft tissues, which is not synonymous with obesity, affects the visibility of organs in the abdominal cavity, including the liver, and limits the accuracy of the examination, e.g. in renal and heart failure, and in other systemic diseases.

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Research