Purpose: To estimate Intra-Inter Observer Variability (Ia/IeOVar) of measurements of liver
fibrosis using ShearWave Elastography (SWE) and to propose efficient ways for an appropriate
estimation of fibrosis in cirrhotic patients.
Material and methods: We studied 112 cirrhotic patients using SWE. All patients had liver biopsy performed
in period not exceeding ± 4 months from US examination. A Transient Elastography TE
(Fibroscan) examination has been performed to 82 of those patients in a period not
exceeding ± 1 month from US/SWE examination.
All patients had US examination and SWE of the liver performed by two independent
examiners. Each examiner performed a third measurement of SWE using a modified protocol
in order to equalize the differences between neighbouring liver segments. The findings
were compared for fibrous liver staging (F-stage) which was pathologically classified
using liver biopsy.
The diagnostic performance of SWE and a TE (Fibroscan) was estimated comparing with
F-stage diagnosis of liver biopsy.
Results: We observed important Ia/IeOVar differences in SWE measurements, calculated in kPa,
during the first part of the study, using the initial protocol.
To reduce Ia/IeOVar: -We choose a SWE- representative liver ROI giving the possibility
to the examiner for an arbitrary traced SWE ROI; six elastography images and analysed
with a prototype analysis software calculating mean of relative strain value, standard
deviation of relative strain value, ratio of blue area in the analysed region, kurtosis-skewness
of strain histogram and entropy. Better correlation of the SWE measurement in all
stages of histologically proven liver fibrosis: F1/F2/F3/F4 with revised protocol.
Conclusion: TE and SWE of the liver are effective and reliable ways to estimate liver stiffness
and fibrosis and have good correlation with histologically proven F-stage. We propose
a modified, tissue specific and adapted to the liver anatomic features SWE protocol
in order to limit Ia/IeOVar.
