Transient micro-elastography:A novel non-invasive approach to measure liver stiffness in mice

AIM:To develop and validate a transient micro-elastography device to measure liver stiffness(LS) in mice.METHODS:A novel transient micro-elastography(TME) device,dedicated to LS measurements in mice with a range of measurement from 1-170 kPa,was developed using an optimized vibration frequency of 300 Hz and a 2 mm piston.The novel probe was validated in a classical fibrosis model(CCl4) and in a transgenic murine model of systemic amyloidosis.RESULTS:TME could be successfully performed in control mice below the xiphoid cartilage,with a mean LS of 4.4 ± 1.3 kPa,a mean success rate of 88%,and an excellent intra-observer agreement(0.98).Treatment with CCl4 over seven weeks drastically increased LS as compared to controls(18.2 ± 3.7 kPa vs 3.6 ± 1.2 kPa).Moreover,fibrosis stage was highly correlated with LS(Spearman coefficient = 0.88,P < 0.01).In the amyloidosis model,much higher LS values were obtained,reaching maximum values of > 150 kPa.LS significantly correlated with the amyloidosis index(0.93,P < 0.0001) and the plasma concentration of mutant hapoA-□(0.62,P < 0.005).CONCLUSION:Here,we have established the first non-invasive approach to measure LS in mice,and have successfully validated it in two murine models of high LS.