Liver elastometry: fibroscanning

Vibration-controlled transient elastography (VTE) measures liver tissue stiffness in kilopascals. Higher stiffness indicates a higher risk of advanced fibrosis and cirrhosis. This noninvasive, radiation-free method takes approximately 10-15 minutes and is suitable for repeated monitoring during treatment and lifestyle changes. In most clinical scenarios, it eliminates the need for a biopsy or significantly reduces its need. [1]

The technology has become a key component of risk stratification algorithms for metabolically associated fatty liver disease, viral hepatitis, alcoholic liver disease, autoimmune diseases, and cholestatic diseases. Major guidelines recommend a two-step approach: first, a simple biochemical index, then elastography to confirm or exclude advanced fibrosis. This reduces the number of false positives and directs appropriate referrals to a specialist. [2]

The method is widely recognized in professional society guidelines. For viral hepatitis C, it is integrated into simplified management schemes in general practice. For metabolic liver disease, it is recommended as part of the workup for patients with cardiometabolic risk factors and steatosis. For portal hypertension, liver stiffness values are used in clinical decision-making rules. [3]

FibroScan devices have undergone regulatory safety assessment. The current approval indicates that they are intended for use in adults and children, that some models can measure spleen stiffness, and that previous contraindications related to pregnancy and active implantable devices have been eliminated. This is reflected in the updated labeling warning about the lack of evidence in these groups. [4]

How does the method work and what parameters will you receive?

The probe generates mechanical microvibrations at a frequency of approximately 50 hertz. The returning shear wave is tracked by ultrasound, and the device calculates the propagation velocity and converts it into kilopascals. The denser the tissue, the faster the wave travels and the higher the resulting value. The system can also evaluate ultrasound attenuation in decibels per meter—an indirect indicator of fatty liver infiltration, known as the controlled attenuation parameter. [5]

The liver stiffness result is interpreted as the median of multiple successful measurements. Quality is considered acceptable when at least 10 valid attempts are obtained, the success rate is at least 60%, and the interquartile range does not exceed 30% of the median. These criteria reduce the risk of erroneous conclusions and improve reproducibility. [6]

For obese patients, an extended XL probe is used, which reduces the risk of technical failure. However, current data and guidelines recommend using the same diagnostic thresholds for different probes when properly selected based on morphometry. [7]

Some devices support spleen stiffness measurement to assess portal hypertension and narrow the "gray zone" in decision making. This indicator is increasingly being included in algorithms, complementing liver stiffness and platelet counts. [8]

When is the test prescribed and how does it help?

Elastometry is prescribed for chronic liver diseases for non-invasive assessment of the stage of fibrosis, the risk of complications, and the need for more intensive monitoring. This applies to metabolically associated liver disease due to obesity and diabetes, alcoholic liver disease, viral hepatitis B and C, as well as autoimmune hepatitis and cholestatic diseases. [9]

In primary care, a simple FIB-4 index is often used as a starting point. If it is elevated, the next step is elastometry to rule out or confirm advanced fibrosis. This cascade improves the accuracy of patient selection, simplifies routing, and allows for the economical use of resources. [10]

In viral hepatitis C, liver stiffness is used to predict cirrhosis and determine screening for complications and frequency of follow-up, with biopsy not required in most patients. In hepatitis B, noninvasive methods are used serially to monitor the progression or regression of fibrosis during therapy. [11]

In portal hypertension settings, stiffness values help select individuals who can safely delay endoscopy based on a combination of the index and platelet count, and identify those likely to have clinically significant portal hypertension.[12]

Table 1. Main clinical tasks of elastometry

Task	What does it show?	Clinical decision
Detection of advanced fibrosis	Probability of severe fibrosis and cirrhosis	Need for referral to a hepatologist and increased monitoring
Evaluation of portal hypertension	Risk of clinically significant portal hypertension	The need for primary endoscopy or possible delay
Evaluation of steatosis	Controlled attenuation parameter, dB per meter	Prescribing measures to reduce body weight and correcting risk factors
Dynamics over time	Changes in hardness with treatment and lifestyle modification	Adjustment of therapy and monitoring frequency

How to prepare and how the examination is conducted

Eating increases instantaneous liver hardness values, so a fasting period of at least 3 hours is required before testing. This is a general rule for all hardness measurement technologies and is important for accurate comparison of values between visits. [13]

The patient lies supine with their right hand behind their head. The transducer is placed in the intercostal space above the right lobe of the liver. The standard protocol involves a series of short "shots," after which the system automatically calculates the median and range. The procedure is painless and does not require anesthesia or contrast. [14]

Probe selection is determined by anthropometric data. In obese individuals, the XL probe reduces the risk of technical failure. If the measurement is still unsuccessful, alternatives include shear wave elastography using an ultrasound machine or magnetic resonance elastography. [15]

The quality of the result must be assessed based on the number of valid attempts, the success rate, and the ratio of the interquartile range to the median. If the criteria are not met, the conclusion should be considered invalid, and a repeat should be planned with proper preparation and proper probe selection. [16]

Table 2. Preparation and protocol

Stage	Requirement	Comment
Hunger pause	At least 3 hours	Otherwise, the liver hardness will be overestimated.
Position	Lying on your back, right hand behind your head	Improves acoustic access
Series of measurements	At least 10 valid	Automatic median as a result
Quality control	Success ≥60%, interquartile range ≤30% of the median	Mandatory part of the protocol

Limitations and situations where the result may be false

There are conditions that temporarily increase liver stiffness without true fibrosis. These include acute hepatitis with elevated enzyme levels, extrahepatic cholestasis, venous congestion in heart failure, recent alcohol consumption, and eating shortly before the test. In these cases, correction of the condition and repeat testing are recommended. [17]

In alcoholic liver disease, active inflammation significantly increases the index. Guidelines recommend repeating the measurement after a period of abstinence of at least a week with elevated enzyme values to avoid falsely elevated values and misclassification of risk. [18]

In cases of severe ascites, this method is technically unsuitable due to the physics of wave propagation through fluid. In such situations, shear-wave ultrasound techniques on a stationary apparatus or magnetic resonance elastography are considered. [19]

Obesity and thick soft tissues impede mechanical impulse transmission and signal reception. Using the XL probe significantly reduces the risk of failure, but does not completely eliminate the problem, so access point selection and recalibration are important. [20]

Table 3. Common sources of errors

Factor	Impact on the result	What to do
Acute hepatitis, AST or GGT significantly higher than normal	False increase	Repeat after the inflammation has subsided.
Extrahepatic cholestasis	False increase	Exclude obstruction before elastometry
Venous congestion in the liver	False increase	Compensate for heart failure
Recent food or alcohol consumption	False increase	Fasting and abstinence
Ascites	Technical unsuitability	Alternative elastography or MR elastography

How to Interpret Numbers: Practical Thresholds

There are no single "universal" thresholds for all diseases, but working ranges are used in clinical practice. A value of less than 8 kilopascals most often excludes significant fibrosis. A range of 12-15 kilopascals and above is highly likely to indicate advanced fibrosis, especially in viral hepatitis, while values around 12.5 kilopascals have historically been used as a benchmark for cirrhosis in hepatitis C. Interpretation is always based on the underlying disease, biochemistry, and measurement quality. [21]

For metabolically associated liver disease, a stiffness of less than 8 kilopascals has a high negative predictive value for excluding advanced fibrosis, but the positive predictive value of high values is lower due to frequent false increases. Therefore, repeat measurements and combination with other noninvasive tests are used to confirm a high result. [22]

Viral hepatitis offers clearer thresholds and higher diagnostic accuracy than fatty liver disease. However, treatment today rarely requires biopsy, as a combination of noninvasive tests provides sufficient confidence in clinical decisions. [23]

If the indicator falls into the "gray zone" between the lower exclusion and upper confirmation thresholds, the decision is made based on a combination of factors, with the possibility of recurrence within a few months after lifestyle and risk factor adjustments. This approach reduces the risk of errors and unnecessary invasive procedures. [24]

Table 4. Working interpretation thresholds for clinical tasks

Clinical task	Threshold zone, kPa	Note
Rule out advanced fibrosis	Less than 8	High negative predictive value
Suspect advanced fibrosis	12-15 and above	Consider the etiology and activity of inflammation
Probable cirrhosis in hepatitis C	Around 12.5 and above	Historical benchmark for cirrhosis in some patients
Risk staging using the "rule of five"	10, 15, 20, 25	Used in portal hypertension

Table 5. Steatosis assessment by the controlled attenuation parameter

Degree of steatosis	Range, dB per meter	Comment
S0	Less than 248	Without steatosis
S1	248-267	Mild steatosis
S2	268-279	Moderate steatosis
S3	280 and above	Severe steatosis

Note: In obesity and diabetes, cut-offs may shift, so values should be interpreted taking into account the clinical context and the variability of measurements. [25]

Portal hypertension and the decision to perform endoscopy

The current Baveno consensus suggests using a combination of liver stiffness and platelet count to assess clinically significant portal hypertension. A stiffness of 25 kilopascals or greater suggests its presence, while values of 15 or less combined with platelets of 150 × 10^9 per liter or greater exclude it in most patients. This helps avoid unnecessary initial endoscopy. [26]

If a patient avoids endoscopy based on these criteria, annual elastometry and platelet counts are recommended. If stiffness increases to 20 or higher or platelets decrease to 150 × 10^9 per liter or lower, endoscopy should be considered again. This monitoring captures changes in risk over time. [27]

Adding spleen stiffness reduces the "gray zone" and increases certainty. In studies, a threshold of approximately 40 kilopascals for spleen stiffness in combination with the Baveno criteria significantly reduced the proportion of indeterminate cases while maintaining reliability. [28]

Thus, elastometry is not only a tool for staging fibrosis, but also a basis for stratifying portal risk and making decisions about the need for invasive procedures. [29]

Table 6. Baveno algorithm for clinically significant portal hypertension

Step	Criterion	Action
The exclusion rule	Liver stiffness ≤15 kPa and platelets ≥150 × 10^9 per liter	Endoscopy is usually not required.
Confirmation rule	Liver stiffness ≥25 kPa	High probability, consider prophylaxis and endoscopy
Dynamic control	Repeat stiffness and platelets annually	If the risk increases, return to endoscopy
Narrowing the "gray zone"	Add spleen stiffness of about 40 kPa	Increasing decision certainty

Comparison with alternatives and place in algorithms

Shear wave ultrasound techniques demonstrate comparable accuracy for advanced fibrosis in a number of scenarios, but are operator-dependent and less standardized. Magnetic resonance elastography demonstrates the highest accuracy, particularly in metabolic liver disease, but is more expensive and less accessible. Therefore, transient elastography remains the method of choice in most cases. [30]

Primary care algorithms for metabolic liver disease utilize a cascade: first, FIB-4, then elastometry to confirm risk. This approach is recommended by a joint clinical guideline of European societies and supported by updated recommendations for the prevention and management of non-communicable liver diseases. [31]

In viral hepatitis C, simplified protocols in primary care use liver stiffness as one of the criteria for predicting cirrhosis and planning further screening for complications. This reduces delays in therapy initiation and lowers barriers to accessing treatment. [32]

In patients with hepatitis B, current recommendations suggest performing non-invasive assessment of fibrosis regularly, at intervals of up to 12-24 months, which allows for timely changes in monitoring and treatment tactics depending on the dynamics. [33]

Table 7. Strengths and weaknesses of the methods

Method	Accuracy for advanced fibrosis	Availability	Operator influence	Notes
Transient elastography	High	High	Low	The method of choice for most routes
Shear wave elastography on an ultrasound machine	Comparable	Average	Higher	Suitable for ascites and difficult access
Magnetic resonance elastography	The highest	Below	Low	Expensive and less accessible

Special groups and security

Pediatric protocols consider chest circumference and body weight for tube selection, as well as the same quality criteria as in adults. Standards for the controlled attenuation parameter in children are gradually being refined, and threshold values for distinguishing between degrees of steatosis are being proposed. [34]

The updated registration documentation specifies expanded indications for adults and children and the elimination of previous contraindications related to pregnancy and implantable devices, with the caveat that large studies in these subgroups are lacking. In practice, this means an individual assessment of benefits and risks, taking into account the clinical situation. [35]

In cases of severe ascites, transient elastography is technically inapplicable, and in cases of obesity, proper probe selection is required. These limitations must be taken into account to avoid false positives and missed clinically significant disease. [36]

Adverse events during the study are extremely rare, the method does not involve ionizing radiation and does not require the introduction of contrast, which makes it convenient for serial monitoring over many years. [37]

Table 8. Pediatrics and other special situations

Situation	What to consider	Solution
Childhood	Selection of a probe based on morphometry, quality criteria are the same	Follow protocols for the number of valid attempts
Pregnancy	There is less data, the contraindication has been removed from the labeling.	Individual assessment and informed consent
Implantable devices	The previous contraindication has been removed from the labeling.	Consider potential artifacts and clinical context
Ascites	The wave does not pass through the liquid	Consider alternative methods

Monitoring and Dynamics: Understanding Changes Over Time

A reduction in liver stiffness with etiotropic therapy and lifestyle modification is associated with a reduced risk of decompensation. A practical guideline is a 20% reduction, reaching a value below 20 kilopascals, or a reduction to less than 10 kilopascals, which is associated with a more favorable prognosis. [38]

In metabolic liver disease, regular testing allows for monitoring the effects of weight loss and risk factor correction. In primary care algorithms, the monitoring interval is selected individually based on the patient's baseline risk and comorbidities.

In patients with hepatitis B, guidelines recommend performing noninvasive fibrosis assessment periodically, for example every 12–24 months, to promptly adjust surveillance strategies. This approach reduces the need for biopsies and improves the safety of long-term management. [39]

In portal hypertension cases, annual platelet counts and measurements allow for timely transition from the low-risk group to the observation group with endoscopy if the risk increases. This is part of the dynamic monitoring according to the Baveno criteria. [40]