Preliminary Study Of Shear Wave Elasticity Imaging Technology In The Application In Diagnosis And Grading Of Nonalcoholic Fatty Liver Disease

Objective: To explore the application value of shear wave elastography(SWE) in diagnosis of nonalcoholic fatty liver disease(NAFLD),by detection and analysis the liver stiffness measurement(LSM)of rabbits with NAFLD by SWE,and comparison the LSM with the pathologic histology and blood biochemical value, in order to provide a practical and noninvasive clinical diagnosis technology of NAFLD.Methods: 45 New Zealand white rabbits were divided randomly into the experimental group(n=35,with high fat diet) and the control group(n=10,with normal diet). The high-fat diet were made of 1% cholesterol, 5% lard, 10% egg yolk powder and 84% of normal diet. The total test time was 24 weeks. We tested the LSM and blood biochemical value of all the rabbits in time of 16 th and 24 th week. We also tested the LSM of the normal control group(n=10) in the different depth of liver capsule in time of 16 th week. We randomly selected 4 rabbits of experimental group(n=2) and control group(n=2) after ultrasonic testing in 16 th week and observed the liver histopathology. Killed all the rabbits and observed the liver histopathology after the ultrasonic test at the time of 24 th weekend. Independent samples T-test of the various indexs of the rabbits in the two groups was performed using SPSS statistical software, version 22(SPSS Inc., Chicago, IL, USA) with all the data displayed as means±standard deviation. Pearson’s correlation coefficient was used for analysis the LSM with the liver fibros(LF) and blood biochemical value,and the receiver operating characteristic curve(ROC) was constructed to analyze the detection efficiency of LSM in the diagnosis of LF.Results:1 The ultrasonic testing results:(1) LSM in experimental group were higher than the control group in time of 16 th and 24 th week,the difference has statistical significance, and the LSM in the experimental group in time of 24 th week was greater than the LSM in time of 24 th week(17.48±7.22) k Pa vs(10.31±1.99)k Pa, the difference is statistically significant(t=10.857,P<0.05);(2) The difference of LSM between different level of LF had statistical significance(F=390.381, P<0.001), the degree of LF and LSM showed a linear correlation(0.940, P=0.000).(3)The areas under the ROC curve(AUC)was 0.918 when LSM diagnosis LF≥S1, AUC was 0.933 when LF≥S2, AUC was0.966 when LF≥S3, AUC was 0.974 when LF=S4(early cirrhosis). Based on the standard of histopathological,the LSM of rabbits showed significant correlation with liver steatosis(r=0.87, P<0.01) in time of 24 th week in all the 36 rabbits. when the LF was in S1 and S2, LSM and liver steatosis were positively correlated(P<0.05), but liver steatosis degree showed no correlation with LSM. when the LF in S3 and S4.(4)The mean LSM of control group(n=10)at different depths 1.0cm, 1.5cm, 2.0cm were(5.21±0.88) k Pa,(5.57±1.23) k Pa,(5.82±1.27 k Pa) respectively in time of 16 th week, and with the increase of the depth the LSM increase gradually. and three sets of data between pairwise comparison, It is found that, there was a significant difference between the 1.0cm group and 2.0cm group(t=-2.156, P= 0.035), and differences between the groups of 1.0cm and 1.5cm, 1.5cm and 2.0cm were no statistical significance(t=-0.766, P=0.447;t=-1.302, P=0.198).2 Results of blood biochemical indexes: Over time, the blood biochemical indexes AST, ALT, TG, TC, LDL-C, VLDL-C, TP, ALP, GLB,GGT, TBIL, DBIL and IBIL were increased gradually in the experimental group with all had statistically significant differences(P<0.05), the blood biochemical indexes ALB and A/G decreased gradually in experimental group with all had statistically significant differences(P<0.05).There was no significant difference in blood biochemical indexes in the control group(P>0.05).3 Correlation between blood biochemical values and LSM: In time of 24 th week, the LSM showed a linear positive correlation with VLDL-C, TP, GGT, IBIL(r=0.368, P=0.027; r=0.325, P=0.046; r=0.392, P=0.02; r=0.358, P=0.031), and the LSM showed a linear negative correlation with ALT and ALP(r=-0.415, P=0.016; r=-0.509, P=0.003).Conclusion:1. It is feasible to establish NAFLD animal model by high fat feeding.2. SWE has high accuracy in the diagnosis and grading of NAFLD in rabbits,and may have a good application value in the evaluation of patients with NAFLD.3. The detection depth of SWE imaging has a certain effect, with the depth increase, SWE measured value has increased tendency.4. Blood biochemical indexes VLDL-C, TP, GGT, IBIL with Young’s modulus value has linear positive correlation; ALT and ALP with Young’s modulus value has linear negative correlation.