Liver Magnetic Resonance Diffusion Weighted Imaging As Well As Liver Lobe Volumes And Ratios Of Them To Spleen Volume For Quantitativly Evaluation Of Liver Fibrosis: An Experimental Study

Objective: To determine the feasibility and value of magnetic resonance（MR） diffusion weighted Imaging （DWI） as well as liver lobe volumes andratios of them to spleen volume for quantitativly evaluation of liver fibrosis.Methods: Sixteen healthy minipigs （6males,10females） wereprospectively used to model liver fibrosis, and underwent abdominal DWIusing b=300,500and800s/mm²followed by MRI dynamiccontrast-enhancement scans on0,5th,9th,16th and21st weekend afterbeginning of modeling the disease. Liver apparent diffusion coefficient （ADC）values were obtained on DWI. The volume parameters of liver including leftlateral liver lobe volume （LLV）, left medial liver lobe volume （LMV）, rightliver lobe volume （RV）, caudate lobe volume （CV）, the ratios of LLV to SV（LLV/SV）, LMV to SV （LMV/SV）, RV to SV （RV/SV）, CV to SV （CV/SV）were measured on enhanced MRI. After MRI, liver biopsy was performed,and pathological specimens were scored using the human METAVIRclassification system. Statistical analyses were performed on SPSS13.0.Results:（1） ADC values decreased with increasing stage of fibrosis for b=300,500and800s/mm²（r=-0.418,-0.535and-0.622, respectively; all P <0.05）. For b=300s/mm², ADC value could distinguish F0-1from F2-4（P <0.05）, but it could not distinguish F0-2from F3-4（P>0.05）. For b=500or800s/mm², ADC values could distinguish F0-1from F2-4, and F0-2fromF3-4（P <0.05）. In addition, ADC values obtained on b=500s/mm²could predict≥F2(cutoff,1.5110^-3mm²/s) and≥F3(cutoff,1.4410^-3mm²/s), withthe AUC of0.803and0.847, sensitivity of82.6%and78.8%, and specificityof76.7%and80.0%, respectively. ADC values obtained on b=800s/mm²could predict≥F2(cutoff,1.2910^-3mm²/s) and≥F3(cutoff,1.2310^-3mm²/s), with the AUC of0.848and0.887, sensitivity of78.3%and84.8%,and specificity of80.0%and81.2%, respectively.（2） LLV, CV increased withincreasing stage of fibrosis （r=0.711,0.526, respectively; all P <0.05）. RVand LMV increased from F0to F2, but decreased from F2to F4. RV/SVdecreased from F0to F1, increased from F1to F2, and decreased from F2toF4. LLV/SV, LMV/SV and CV/SV decreased from F0to F4（r=-0.566-0.748and-0.620, respectively; all P <0.05）. LLV, CV, LLV/SV, LMV/SV,RV/SV and CV/SV could distinguish F0-1from F2-4, and F0-2from F3-4（P<0.05）. LLV could predict≥F2（cutoff,163.5cm³）, with the best AUC of0.893, sensitivity of88.9%, specificity of86.4%. LMV/SV could predict≥F3（cutoff,0.415）, with the best AUC of0.946, sensitivity of90%, specificity of83.3%.Conclusions: Liver ADC values （b=500or800s/mm²）, LLV, CV,LLV/SV, LMV/SV, CV/SV could be used for quantitativly evaluation of liverfibrosis. Among these parameters, LLV could be the best indicator forpredicting≥F2, and LMV/SV could be the best indicator for predicting≥F3.