Intravoxel Incoherent Motion Diffusion-weighted MR Imaging for Characterization of Focal Pancreatic Lesions

Purpose: To evaluate the diagnostic potential of apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM)-derived parameters for differentiation of common pancreatic tumors, chronic pancreatitis, and normal pancreas and for characterization of the malignancy potential of intraductal papillary mucinous neoplasms (IPMNs). and Materials and Methods: The institutional review board approved this retrospective study, and informed consent was waived. Ninety-three consecutive patients with surgically resected and pathologically confirmed pancreatic tumors (39 pancreatic adenocarcinomas [PACs], 17 neuroendocrine tumors [NETs], and 37 IPMNs), seven patients with chronic pancreatitis, and 26 patients with a normal pancreas were included in this study. All patients underwent pancreatic 3.0-T magnetic resonance imaging, including IVIM diffusion-weighted imaging with 10 b values used (from 0 to 1000 sec/mm(2)). The ADC, slow component of diffusion (D-slow), incoherent microcirculation (D-fast), and perfusion fraction (f) were calculated. Steel-Dwass and Mann-Whitney U tests were used for comparison. The diagnostic performance of the parameters was evaluated by using receiver operating characteristic (ROC) analysis with Bonferroni correction. Results: Among ADC- and IVIM-derived parameters, D-fast and f values of PACs were significantly lower than those of normal pancreas, chronic pancreatitis, and NETs (all P < .05 in post hoc analyses). For differentiation of PACs from NETs, f and D-fast showed a significant difference (P < .0001 for both) and were more useful parameters than ADC and D-slow in ROC analysis (all P < .05). Malignant IPMNs had significantly lower ADC and D-slow values and higher D-fast and f values when compared with benign IPMNs (all P < .05). In ROC analysis, f showed the highest area under the ROC curve value for distinguishing malignant from benign IPMNs. Conclusion: IVIM-derived perfusion-related parameters could be helpful for the differentiation of common malignant tumors in the pancreas and for distinguishing malignant from benign IPMNs. D-fast and f were more valuable parameters in the differentiation of PACs from NETs than were ADC and D-slow.