The Experimental Study On Magnetic Resonance Imaging T1 Mapping Of Liver Fibrosis In Rats

Part one:Comparison the value of T1 mapping,T2 mapping,and BOLD diagnosing liver fibrosis in ratsObjective To assess the value of T1 mapping,T2 mapping and blood oxygenation level dependent imaging（BOLD）in diagnosing and staging the liver fibrosis in rats.Methods 60 liver fibrosis model rats established by subcutaneous injection of carbon tetrachloride（CCL₄）olive oil were underwent liver MRI scan including the following sequences:T1mapping、T2mapping、BOLD imaging.T1（ms）,T2（ms）and R2^*（Hz）values measured in liver parenchyma compared with liver histological specimens.The Spearman level correlation analysis was used to analyze the correlation between pathological stages of liver fibrosis(S_0-4)and the MRI parametes.Multiple group comparisons were made by one-way ANOVA.We used receiver operating characteristic（ROC）curve to evaluate diagnostic efficacy of T1,T2 and R2^*values.P<0.05 was considered to be statistically significant.Results（1）60 rats were all survival during the model making,7 rats were suffocated to death because of too tightabdominal bundle in MRI scan,53 rats were performed withMRI scans.The pathological stages of liver fibrosis in rats were classified into stage S₀（n=6,all in the control group）,stage S₁（n=10）,stage S₂（n=19）,stage S₃（n=11）,stageS₄（n=7）.（2）T1,T2 and R2^*values were statistically different in five pathological stages,and S₀ verse each stage of liver fibrosis displayed significant difference in T1 value,same result in mild liver fibrosis(S_1-2)verse severe liver fibrosis(S_3-4)（p<0.05）.While there were no significant difference in S₁ verse S₂,S₃ verse S₄（p>0.05）.（3）Area under the curve（AUC）showed T2 value>T1 value>R2^*value.（4）T1 value was positively correlated with the pathological stages.The relationship between T2 and R2*values had no significant difference（p>0.05）among each stage of liver fibrosis.Conclusion T1 mapping and T2 mapping manifested higher efficacy than BOLD in diagnosing liver fibrosis in rats.And T1 mapping was the most valuable indicator for evaluating the severity of liver fibrosis in rats,which had higher accuracy and reproducibility than BOLD and T2 mapping.Part two: The diagnostic value of T1 mapping staging of liver fibrosis in rat and the relationship between T1 mapping and serum fibrosis markersObjective To investigate the diagnostic value of T1 mapping staging of liver fibrosis in rat and the relationship between T1 mapping and serum fibrosis markers.Materials and Methods The liver fibrosis models were performed with MRI T1 mapping and serum markers,T1 value（ms）and serum fibrosis markers include hyaluronic acid（HA）,procollagen type Ⅲ peptide（PⅢP）,type Ⅳ collagen（C-Ⅳ）and laminin（LN）levels（μg/L）were measured.The rats were divided into control group（S0）,mild group（S1^S2）and severe group（S3^S4）according to the pathological stages of liver fibrosis.Multiple group comparisons were made by one-way ANOVA,and receiver operating characteristic（ROC）curve was used to evaluate the diagnostic value of T1 value and serum markers in liver fibrosis staging,meanwhile the relationship between them were analyzed by Spearman level correlation analysis.P<0.05 was considered to be statistically significant.Results（1）60 rats were all survival during the model making,but 7 rats were suffocated to death because of too tight abdominal bundle in MRI scan,53 rats were performed with MRI scans and blood collection,while the blood samples including 19 cases of hemolysis and 34 available cases.The pathological stages of liver fibrosis in rats were classified into stage S0（n=5,all in the control group）,stage S1（n=6）,stage S2（n=12）,stage S3（n=6）,stage S4（n=5）.（2）The difference of T1 value between mild group and severe group had statistically significant,the same result was found between and severe liver fibrosis（P<0.05）,But there were no statistically signicant difference between control group and mild group（P>0.05）.The difference of HA、C-IV levels between mild group and severe group had statistically significant（P<0.05）,but no significant difference found between control group and mild group,either between control group and severe group（P>0.05）.There were no statistically significant difference of PⅢP and LN in different groups（P>0.05）.（3）Estimated by T1 value and serum marker levels,the order of area under the curve（AUC）of liver fibrosis judgement was T1+HA+P III P（0.85）>T1（0.72）>P III P（0.68）> HA（0.61）>C-IV（0.58）>LN（0.46）;and the order of area under the curve（AUC）of liver fibrosis severity was T1+HA+P III P（0.93）>T1（0.87）>C-IV（0.75）>P III P（0.70）> HA（0.67）>LN（0.57）.（4）There was positive relationship between T1 and serum markers.A significant correlation was found between T1 value and HA（r=0.412,p<0.05）,but had no correlation between T1 value and C-IV,PIIIP,LN（p>0.05）.Conclusions T1 mapping had a certain great diagnostic value in staging liver fibrosis,while the combination of T1 mapping and serum markers delivered even better diagnostic value.