Elastography in MASLD: Fibrosis Thresholds by WFUMB 2024
Clinical Significance of LSM in MASLD
Liver elastography in MASLD assesses liver stiffness measurement, LSM, in kPa. It is not a direct measurement of collagen but an integral indicator of tissue stiffness. LSM is influenced by fibrosis, inflammatory activity, liver congestion, cholestasis, food intake, technical conditions of the study, and the quality of the acoustic window. Therefore, the conclusion should not turn a single kPa value into an 'exact stage' of fibrosis without clinical context.
In the update WFUMB Guideline/Guidance on Liver Multiparametric Ultrasound: Part 1, 2024, emphasis is placed on etiologically oriented interpretation. For MASLD, the most useful are not the fine gradations of F0–F4, but the thresholds for exclusion and confirmation of advanced fibrosis, as this group changes routing and monitoring.
Main Thresholds by WFUMB 2024
| Clinical Situation | LSM, kPa | Interpretation |
|---|---|---|
| MASLD | <8 | Advanced fibrosis is unlikely; exclusion threshold |
| MASLD | 8–12 | Intermediate zone; requires correlation with clinical, laboratory indices, and dynamics |
| MASLD | ≥12 | High probability of advanced fibrosis; confirmation threshold |
| Chronic liver disease, general WFUMB guideline | ≤5 | High probability of normal liver stiffness |
| Chronic liver disease, general WFUMB guideline | <9 | cACLD is unlikely in the absence of other signs |
| Chronic liver disease, general WFUMB guideline | 9–13 | Borderline zone for cACLD |
| Chronic liver disease, general WFUMB guideline | >13 | cACLD is probable |
| Chronic liver disease, general WFUMB guideline | >17 | Value is concerning for clinically significant portal hypertension |
What the <8 kPa Threshold Excludes
In MASLD, an LSM value of <8 kPa is used as an exclusion threshold for advanced fibrosis. Practically, this means a low probability of fibrosis corresponding to a clinically significant risk group, primarily ≥F3. Such a result does not equal 'healthy liver': the patient may still have steatosis, metabolic risk, initial or moderate fibrosis, or steatohepatitis activity.
In the ultrasound protocol, the correct formulation is: 'Elastography data show no signs of advanced fibrosis' or 'LSM is below the exclusion threshold for advanced fibrosis in MASLD'. It is undesirable to write 'F0' based solely on LSM.
How to Interpret the 8–12 kPa Zone
The 8–12 kPa interval is not a diagnostic dead end but a zone where elastography loses sufficient certainty for independent decision-making. In MASLD, this zone is often encountered: obesity, pronounced steatosis, inflammatory activity, and technical limitations can shift the LSM value.
In this zone, the WFUMB approach suggests a multiparametric assessment: measurement quality, B-mode, signs of chronic liver disease, spleen and portal system, laboratory non-invasive indices, and LSM dynamics. If the clinical risk is high, the patient should not be 'reassured' by an intermediate result; if the risk is low and the measurement quality is good, a repeat assessment in dynamics is advisable.
What ≥12 kPa Means in MASLD
LSM ≥12 kPa in MASLD is the threshold for confirming a high probability of advanced fibrosis. This is not necessarily morphological cirrhosis, but the result requires clinical verification of risk, assessment of cACLD signs, and a decision on specialized monitoring.
In the conclusion, it is better to avoid the categorical phrase 'cirrhosis' without additional ultrasound signs and clinical-laboratory confirmation. More correctly: 'LSM is above the threshold for confirming advanced fibrosis in MASLD'; then list the study limitations and accompanying findings.
Connection with the Universal WFUMB Scale
WFUMB 2024 retains practical general guidelines for chronic liver diseases: ≤5 kPa as a zone of high probability of normal stiffness, <9 kPa as an argument against cACLD, 9–13 kPa as an indeterminate range, >13 kPa as supporting the diagnosis of cACLD, >17 kPa as an alarming level for clinically significant portal hypertension. These values are convenient for a universal report.
However, in MASLD, it is preferable to explicitly indicate the etiological block: <8, 8–12, and ≥12 kPa. This reduces the risk of overdiagnosis in patients with metabolic liver disease and simultaneously helps not to miss advanced fibrosis.
Technical Conditions That Should Be in the Protocol
LSM is interpreted only with a quality study. The protocol should indicate the elastography method, transducer or mode, liver segment, depth and measurement zone if necessary, median LSM value in kPa, reliability criteria according to the used system, and factors that may affect the result. For MASLD, it is especially important to indicate technical difficulty and transducer type, as obesity and narrow intercostal spaces increase the likelihood of unreliable measurements.
If the study is technically limited, WFUMB thresholds cannot be applied mechanically. In such a situation, it is better to provide a diagnostic conclusion with a caveat: 'LSM assessment is limited by the quality of the acoustic window' and recommend repetition under optimal conditions or an alternative method of fibrosis assessment.
How to Write a Conclusion
The optimal structure of the conclusion: diagnosis-guide, LSM number, category by WFUMB for MASLD, and limitations. Example: 'MASLD. LSM 7.4 kPa: value below the exclusion threshold for advanced fibrosis in MASLD by WFUMB 2024. No ultrasound signs of cACLD detected'. For the intermediate zone: 'LSM 9.6 kPa: intermediate range 8–12 kPa; requires correlation with clinical-laboratory data'. For high value: 'LSM 13.1 kPa: above the threshold for confirming advanced fibrosis in MASLD'.
Such wording is understandable to hepatologists, therapists, and endocrinologists: it separates the measurement from the clinical diagnosis and indicates the further level of risk.
Frequently asked questions
Can LSM 6–7 kPa be reported as F0–F1 in MASLD?
It is better not to report an exact F stage. According to WFUMB 2024, LSM <8 kPa in MASLD is used as an exclusion threshold for advanced fibrosis, but it does not exclude steatosis, disease activity, or initial fibrosis.
What to do with LSM 10 kPa in MASLD?
10 kPa falls into the intermediate range of 8–12 kPa. Assessment of measurement quality, clinical-laboratory data, non-invasive risk indices, and dynamic monitoring or further examination are needed.
Is LSM ≥12 kPa in MASLD cirrhosis?
No, cirrhosis is not automatically established. It is the threshold for confirming a high probability of advanced fibrosis in MASLD; a diagnosis of cirrhosis requires correlation with ultrasound signs of cACLD, laboratory data, and clinical picture.