pSWE delivers a quantitative measure of tissue stiffness (expressed in Shear Wave propagation velocity or deduced Young Modulus in KPa) for a small tissue sample.
pSWE is based on a perturbation and a reading phase.
Non-invasive methods such as pSWE 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 pSWE is about
Point Shear Wave Elastography (pSWE) technology is characterized by the generation of a shear wave originated by an Ultrasound focused beam,
which creates a localized perturbation in a small region around a focused shock point.
This perturbative phase is followed by a reading phase in a Region of Interest (ROI) providing a quantitative estimate of liver stiffness inside the ROI.
The ROI is therefore the graphical representation of the considered reading area where the shear wave propagates and where the quantitative analysis is performed.
Tissue Elasticity Evaluation
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 to its original shape after distortion.
Evaluation procedure of elasticity properties involves deformation of a tissue in response to the application of an external load: practically,
two Ultrasound Elastography main modalities are today available: Strain Elastography (Qualitative) and Shear Wave Elastography (Quantitative).
Liver Elasticity Evaluation
The European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) indicated that today noninvasive methods can 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.
pSWE Advantages
Non-invasive solution to evaluate liver fibrosis.
An alternative to gold standard (Liver Biopsy).
Ultrasound guided-imaging technique.
Complementary to a B-mode liver evaluation.
Definitely less expensive than MRI Elastography (MRE).
QElaXto – Esaote pSWE – Intended use
Liver stiffness is demonstrated to be suitably mapped to liver fibrosis stages (Metavir classification).
The scope of QElaXto is the measurement of the Liver Fibrosis levels,
which are related,
according to Metavir classification,
to a level of stiffness up to 15-20KPa (limit F4 over which the Fibrosis becomes Cirrhosis,
irreversible and not curable).
Metavir classification:
F0= no fibrosis,
F1= minimal fibrosis,
F2= fibrosis has occurred and spread inside the areas of the liver including blood vessels,
F3= fibrosis is spreading and connecting to other liver areas that contain fibrosis.
What is usually measured are the F0- F2 Liver Fibrosis levels,
which are reversible with proper therapies.
As a general reference table (differences can be present among Clinical Centers),
the following stiffness ranges are related to corresponding Liver Fibrosis Metavir classifications:
F0-F1 (< 7 kPa),
F2 (7-9.5 kPa),
F3 (9.5-12 kPa),
F4 (> 12 kPa).