What is transition elastography?
Elastography is an ultrasound diagnostic method capable of assessing the degree of elasticity of the tissues in a non-invasive way. Like ultrasound, which is complementary and which cannot be ignored, it is harmless and provides information in real-time.
The application in the medical field of elastography starts with two fundamental assumptions. The first that there are significant differences in the mechanical properties of the various tissues, the second that many pathologies cause a change in tissue elasticity. In general, "benign" fabrics have "elastic" characteristics; on the contrary, "rigid" tissues are usually considered the expression of tumors or chronic inflammatory processes.
The limits of manual palpation are, however, the subjectivity and the impossibility of identifying the different tissue components. Elastography is therefore proposed as an "electronic palpation" technique capable of systematically analyzing the structural differences of the tissues, especially in areas that cannot be adequately assessed with the only clinical medical examination. Elastography is, in fact, highly sensitive to the structural changes that accompany physiological and pathological processes.
- It finds prevalent application in the differential diagnosis between benign or malignant nodules in superficial organs such as breast, thyroid, lymph nodes, and testicles.
- It is indicated for the characterization of prostate nodules and the search for cancer in the peripheral area of the prostate.
- It is useful for assessing the stiffness of the liver in the suspicion of post-hepatitic liver fibrosis or in other non-viral liver diseases.
Fibroscan or transition elastography is a technique that allows you to evaluate the degree of liver fibrosis, as well as the quantification of liver fat. It is a type of non-invasive, fast, reliable, and reproducible exploration. Elastography is especially useful as an alternative to biopsy.
What's it about?
The examination with Fibroscan is a non-invasive examination with a rapid duration, during which the specialist passes an ultrasound probe on the area to be analyzed, which emits a pulse that is propagated in the organ. The numerical result of the speed with which the impulse travels corresponds to the value of the rigidity of the organ itself and therefore is able to provide information about the presence or degree of development of pathology.
Why is it done?
Fibroscan is performed for the diagnosis and monitoring of chronic hepatitis caused by the hepatitis C virus (VHC) of chronic hepatitis caused by the hepatitis B virus (VHB) of the co-infection caused by the hepatitis virus. The hepatitis C and HIV, alcoholic liver, the hepatic steatosis (fatty liver) nonalcoholic, chronic polycystic diseases of liver cirrhosis, and for the monitoring of patients pre- and post-liver transplantation. These are some of the proven uses of elastography.
Preparation for Fibroscan
The patient must go to the clinic for two hours on an empty stomach. He will lie down on a bed with his right arm raised and placed behind the neck. The measurements are performed by means of a transducer or probe, on whose surface a gel is affixed, which is placed in the intercostal area above the right hepatic lobule. The patient sees nothing during exploration. 'M' and XL probes are used for obese patients. A minimum of 10 measurements is made.
What do you feel during the exam?
The operation, which generally lasts 15 minutes, is not painful and is also available for obese patients for whom a larger probe is used. The examination is neither painful nor invasive for the patient, who can return home immediately after the examination.
Meaning of abnormal results
The measurement allows us to know the stage of hepatic fibrosis (hardness), from an initial stage to a more advanced stage (cirrhosis).
Fibroscan: how to measure liver fibrosis in a non-invasive way
fibroscan is a non-invasive instrument capable of measuring steatosis and liver fibrosis
Fibroscan: how does it work?
Fibroscan is an instrument capable of measuring liver fibrosis and steatosis through a pulse elastography technique. It is composed of a particular ultrasound probe, equipped with a low-frequency vibrator capable of generating an elastic wave and a single element transducer used as an ultrasound receiver. In practice, during the procedure, the probe is positioned on the patient's chest at the height of the liver and, due to low frequency and small amplitude shock waves. It is possible to record the speed with which these waves propagate in the liver. In this way, it is thus possible to establish the elasticity and hardness of the organ, the "stiffness," in practice, its degree of fibrosis. But Fibroscan also records the CAP (Controlled Attenuation Parameter), a parameter that estimates liver steatosis, the fat content of the liver.
What are the advantages of fibroscan?
It is an examination that is easy to perform, painless, non-invasive, which usually takes a few minutes to perform the ten planned measurements. The results provided are highly reproducible, and the procedure can be repeated over time, so as to evaluate the evolution of the pathology over the years.
And again, the size of the liver tissue that can be analyzed with Fibroscan is about 100 times greater than that of a sample obtained from the biopsy. Furthermore, with this method, it is possible to highlight any discrepancies between the different lobes of the liver during the same session, positioning the probe on distinct intercostal spaces. The system was created in such a way as to reduce the possibility of error, refusing estimates in the event that the measurement is not carried out appropriately. It also provides the specialist with two extremely important data to confirm the correct execution of the procedure, the success rate (i.e., the number of useful assessments, which is considered reliable, if equal to or greater than 60%) and the IQR (i.e., the variability of the measurements made, which should not be more than 30% of the stiffness value).
Due to liver elastometry and its accuracy (in particular for the more advanced stages), it is possible to perform a diagnosis of liver cirrhosis close to 100%, as well as evaluate the degree of fibrosis, all without having to resort to hepatobiopsia. This innovative technique is extremely useful for the early diagnosis and monitoring of fibrotic or cirrhotic patients and also allows suspecting the presence of portal hypertension.
Are there any disadvantages?
Rather than disadvantages, Fibroscan has limitations:
- It cannot be performed in the presence of ascites, in obese patients or with narrow intercostal spaces.
- The stiffness values can be altered by food or by the presence of certain conditions such as extrahepatic cholestasis, heart failure, and hypertransaminasemia.
Author: Vicki Lezama