Effect of Inflammation on Fibrosis Staging Measured by Quantitative Elasticity Parameters in Rats With Immune Hepatitis.

OBJECTIVES

To investigate the effect of inflammation on fibrosis staging measured by quantitative elasticity parameters in rats with immune hepatitis.

METHODS

Fifty-two rats were injected with swine serum as a model group, whereas 8 rats were injected with saline as a control group. Rats were randomly subjected to real-time tissue elastography biweekly. Tissue dispersion quantitative analysis was performed to obtain 12 quantitative elasticity parameters: relative mean value, standard deviation, blue area percentage, complexity, kurtosis, skewness, contrast, entropy, inverse difference moment, angular second moment, correlation, and liver fibrosis index. Subsequently, rats were euthanized, and liver specimens were taken for pathologic examination. The Kruskal-Wallis test was used for comparisons among groups. Spearman rank correlation analysis was used for correlation analysis. Receiver operating characteristic curves were used to optimize cutoff values and evaluate the diagnostic performance of the liver fibrosis index.

RESULTS

Except for complexity, kurtosis, and correlation, the other 9 parameters had statistical differences (P < .05), and among these 9 parameters, the liver fibrosis index had the strongest correlation with fibrosis staging (r = 0.809; P < .05). Except for kurtosis and correlation, the other 10 parameters had statistical differences (P < .05), and among these 10 parameters, the liver fibrosis index had the highest correlation with inflammation grading (r= 0.766; P< .05). The fibrosis index cutoff values were 2.35 for stage S1 or higher (area under the curve [AUC], 0.940; sensitivity, 97.1%; specificity, 73.3%), 2.99 for stage S2 or higher (AUC, 0.865; sensitivity, 78.6%; specificity, 81.0%), 3.48 for stage S3 or higher (AUC, 0.924; sensitivity, 94.4%; specificity, 87.1%), and 4.05 for stage S4 (AUC, 0.933; sensitivity, 87.5%; specificity, 95.1%).

CONCLUSIONS

Real-time elastography could be used to noninvasively evaluate fibrosis staging in rats with immune hepatitis. However, inflammation had an effect on the accuracy of this technique.