Intravoxel Incoherent Motion Diffusion Weighted Imaging And T1 Mapping For The Evaluation Of Autoimmune Pancreatitis:A Clinical Study

Purpose:To evaluate the diagnostic performance of intravoxel incoherent motion diffusion weighted imaging(IVIM-DWI)and T1 mapping for the evaluation of autoimmune pancreatitis(AIP).Materials and methods:A total of 26 patients with AIP confirmed by pathology and clinical evaluation,18 healthy volunteers and 39 patients with pancreatic cancer(PC)confirmed histologically underwent IVIM-DWI and T1 mapping with 9 different b values(0,25,75,100,150,200,500,800 and 1000 s/mm~2).The difference of T1 value and IVIM-DWI imaging parameters(true diffusion coefficient[D],pseudo-diffusion coefficient[D*],and perfusion fraction[f])were analyzed between normal pancreas,PC and AIP groups.Receiver operating characteristic curve(ROC)analysis was performed to evaluate the diagnostic performance of the D,D*and f for differentiation between AIP and PC,and AIP and normal pancreas.Results:The mean f value in normal pancreas,PC and AIP was(20.6±4.2)%,(12.0±3.7)%and(9.1±3.1)%,respectively,with statistical difference among groups(P<0.001).The diagnostic performance of f value(area under the ROC curve[AUC]of 0.970 and 0.747,respectively)in differentiating normal pancreas from AIP,and AIP from PC was better than that of T1 value(AUC=0.949,0.685),D(AUC:0.513 and0.582)and D*(AUC:0.825 and 0.493).Conclusion:Perfusion fraction f by IVIM-DWI is a promising method in differential diagnosis of AIP.