Liver Shear Wave Dispersion (SWD): Assessment of Necroinflammation and Viscosity
The Role of SWD in Multiparametric Liver Ultrasound
According to the excerpts, current recommendations for liver elastography are presented in the WFUMB documents (2018 liver elastography guidelines update, 2024) and the ACR-SRU Practice Parameter (2024). Specific numerical thresholds for shear wave dispersion (SWD) to assess necroinflammation and viscosity are not provided in the excerpts — [clarification needed] from the full texts of the mentioned guidelines.
Impact of Inflammation on Elastography Results
The excerpts explicitly state that the presence of inflammation affects the liver stiffness measurement results. Factors requiring control include:
- ALT level (inflammation activity);
- absence of congestion;
- fasting state (according to various materials — ≥2–3 hours or ≥4 hours of fasting).
In the protocol example, an "inflammatory episode" is specifically mentioned as a cause of unacceptable study quality, along with obesity, ascites, cholestasis, and heart failure. This emphasizes that inflammation can elevate stiffness values — clinically linking the issue of necroinflammation with elastometry interpretation.
Principles of Correct Measurement (Based on Protocol Example)
| Parameter | Value |
|---|---|
| Conditions | fasting ≥4 hours, lying on back, right arm above head |
| Access | intercostal, right lobe (segments V–VIII) |
| Depth of interest zone | 1–3 cm from the capsule (capsule not included) |
| Number of measurements | 10 |
| Validity criterion | IQR/Med ≤ 30% |
The specified requirements relate to stiffness measurement (point SWE / ElastPQ). There are no specific quality requirements for SWD in the excerpts [clarification needed].
Approximate Stiffness Thresholds (for Context)
The data in the excerpts pertain to stiffness, not dispersion. According to ElastPQ (EFSUMB): F0–F1 < 7.0 kPa; F ≥ 2 — ≥ 7.0 kPa; F ≥ 3 — ≥ 9.0–9.5 kPa; F4 (cirrhosis) — ≥ 12.0–13.0 kPa. For pSWE/2D-SWE (according to literature): normal (F0) < 5.5–6.0 kPa; F4 > 10–12 kPa (according to several consensuses > 11–13 kPa); in m/s normal < 1.34–1.40 m/s, cirrhosis > 1.8–2.0 m/s. SWD thresholds for viscosity and necroinflammation are absent in the excerpts.
Conclusion Formulation
In the absence of specificity of signs, a cautious formulation with an indication of clinical-laboratory correlation is recommended. Example structure of an elastography conclusion: liver parenchyma stiffness according to point SWE (ElastPQ) — ___ kPa (median of 10 measurements, IQR/Med = ___%).
Frequently asked questions
Are there SWD thresholds for assessing necroinflammation in the excerpts?
No. Specific numerical thresholds for shear wave dispersion (SWD) for necroinflammation and viscosity are not provided in the excerpts — clarification is needed from the full texts of WFUMB and ACR-SRU.
How does inflammation affect liver elastography?
Inflammation (controlled by ALT) affects the stiffness measurement result; an inflammatory episode is listed as a cause of unacceptable study quality and requires consideration in interpretation.
What are the preparation conditions for the study?
Fasting: according to the protocol example ≥4 hours, according to other materials ≥2–3 hours. Position lying on back, right arm above head, intercostal access, right lobe (segments V–VIII).
What is the validity criterion for measurements?
Median of 10 measurements with IQR/Med ≤ 30%. Depth of interest zone 1–3 cm from the capsule, without including the capsule.
Which guidelines regulate liver elastography?
According to the excerpts — WFUMB Guideline/Guidance on Liver Multiparametric Ultrasound (2024, 2018 guidelines update) and ACR-SRU Practice Parameter for Ultrasound Elastography (2024).