Education and training, Cirrhosis, Technology assessment, Technical aspects, Education, Ultrasound, Elastography, Spleen, Liver, Abdomen
P. Zoumpoulis1, E. Panteleakou1, K. Ng2, A. Soultatos1, I. Theotokas1, A. Dell'Era2; 1Athens/GR, 2Shenzhen/CN
Shear Wave Elastography is a non-invasive method that ensures good reproducibility and highly consistent quantitative elastic results in patients with chronic liver diseases (CLD),
to assess liver disease severity (fibrosis) before therapy at a safe level of predictability as an alternative to liver biopsy procedures.
Elasticity Evaluation in the Liver
Tissue has different mechanical properties and elasticity is one of these components.
Elasticity is the property of a material or a tissue to deform under a given stress (for example,
due to external forces applied) and then to restore itself to its original shape after distortion.
In recent years there has been great interest in measuring the stiffness of tissue.
Strain elastography has been popular for a long time,
providing 2D strain imaging of the ROI (region of interest).
Shear wave elastography has gained more attention in recent years,
providing quantitative stiffness measurement by displaying the shear wave propagation speed or the tissue mechanical modulus,
such as shear modulus,
and Young's modulus,
which is most often used to quantify the stiffness.
A high Young's modulus indicates high stiffness with a quantitative approach.
The European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) indicated that non-invasive methods can now be used instead of liver biopsy in patients with chronic hepatitis C to assess liver disease severity (fibrosis) before therapy at a safe level of predictability.
What is 2D STE Shear Wave?
The Sound Touch Elastography (STE) technology is a novel approach developed to display a real-time stiffness image of the ROI.
safe ultrasound pulse is used to generate shear waves based on the acoustic radiation force (ARF) in soft tissue [1,
The system then tracks the propagation of the shear waves and continuously detects and records the displacement of tissue induced by the shear waves in the ROI.
The propagation speeds are calculated,
and the corresponding elastic modulus derived .
Multiple shear waves will be generated in different positions in turn to form a full image.
STE Features and Advantages
- Non-invasive solution to evaluate liver fibrosis as an alternative to gold standard (liver biopsy).
- Elasticity analysis in multiple frames to improve the accuracy and reliability.
- Indication of the stability of tissue motion.
- Indication of the reliability of the Shear Wave within the region of interest.
- Quantification analysis with customizable ROI and structured reporting.
- An adequate B-mode liver image to clearly distinguish the parenchyma and surrounding vessels is a prerequisite.
- It is necessary to avoid structures or inflammatory factors that may lead to an overestimation of liver fibrosis staging.
- Patient fasting and resting 3-4 hours prior to the SWE is recommended.
- Depth higher than 5 cm from the probe surface,
limited acoustic window,
non-cooperative patient breathing,
large amount of ascites,
intercostal wall thickness higher than 25 mm,
BMI > 30 kg/m2,
and waist circumference higher than 100 cm need to be considered.