Spleen Changes Secondary To Liver Fibrosis Evaluated Quantitatively By Magnetic Resonance Imaging: An Experimental Study

Part1Spleen magnetic resonance diffusion weighted imaging forquantitative staging hepatic fibrosis in minipigs: an initial studyAim: To determine whether spleen diffusion weighted imaging (DWI)parameters might classify liver fibrosis stage.Methods: Sixteen minipigs were prospectively used to model liverfibrosis, and underwent spleen DWI by using b=300,500and800s/mm~2on0,5th,9th,16th and21st weekend after beginning of the modeling. Signalintensity ratio of spleen to paraspinous muscles (S/M), spleen exponentialapparent diffusion coefficient (eADC) and apparent diffusion coefficient(ADC) for each b value were statistically analyzed.Results: With increasing stages of fibrosis, S/M for all b values trendedto decrease; and spleen eADC and ADC for b=300s/mm~2trended to decreaseand increase, respectively (all P<0.05). Area under receiver operatingcharacteristic curve (AUC) of spleen DWI parameters was0.777or more byS/M for classifying each fibrosis stage, and0.65or more by eADC and0.648or more by ADC for classifying stage≥3or cirrhosis. Among the spleen DWIparameters, S/M for b=300s/mm~2was the best parameter in classifying stage≥1,≥2and≥3with AUC of0.875,0.851and0.843, respectively; and spleeneADC for b=300s/mm~2was best in classifying stage4with AUC of0.988.Conclusions: Spleen DWI might be used to stage liver fibrosis. Part2Spleen size measured on enhanced magnetic resonance imagingfor quantitatively staging liver fibrosis in minipigsPurpose: To investigate whether and how spleen size measured onmagnetic resonance imaging (MRI) could be used to stage liver fibrosis.Materials and Methods: Sixteen minipigs were used to prospectivelymodel liver fibrosis staged by biopsy. Abdominal gadolinium-enhanced MRIwas performed on0,5th,9th,16th and21st weekend after beginning of themodeling. Splenic maximal width (W), thickness (T), length (L) and area (S)together with spleen volume (SV) and liver volume (LV) were measured onenhanced MRI, and ratio of SV to LV (SV/LV) was calculated. Spleenmultidimensional index1and2were obtained by W×T×L and S×L,respectively. Statistical analyses were performed to determine whichparameter could best stage the fibrosis.Results: W, T, L, S, SV, index1and2, and SV/LV tended to increasewith increasing stages of fibrosis (r=0.46–0.796, all P<0.001), and mightpredict liver fibrosis stage≥1,≥2,≥3and4(area under receiver operatingcharacteristic curve (AUC)=0.697–1.0). Among the parameters, splenicindex1, SV, and SV/LV might be best for predicting stage≥1(AUC=0.941),≥2or≥3(AUC=0.875or0.978, respectively), and4(AUC=1.0), respectively.Conclusion: Spleen size measured on MRI could be indexes for stagingliver fibrosis.