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).
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).
© RSNA, 2013