Magnetic resonance diffusion-weighted imaging in the characterization of pancreatic mucinous cystic lesions

Aim The aim of the study was to evaluate the utility of diffusion-weighted imaging (DWI), including apparent diffusion coefficient (ADC) measurement, in order to differentiate mucinous cystic neoplasms (MCNs) from intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. Materials and methods Fifty cases of IPMN with a total of 62 lesions, and eight cases of MCN, were retrospectively selected for the study. The cases of IPMN were selected using multimodality clinical or histopathological criteria, while all MCN lesions were histopathologically proven. DWI was carried out using b values of 500 and 1000s/mm 2 . Visual assessment was performed by two radiologists who used two categories (low-iso or high signal intensity). ADC values of the lesions were also calculated. Fisher's exact test and the Mann–Whitney U test were used for statistical analysis. Results All IPMN lesions demonstrated low-iso signal intensities compared with the pancreatic parenchyma on DWI. Two of the MCN lesions demonstrated low-iso signal intensities, and six lesions demonstrated high signal intensities. The ADC values for IPMNs (mean 2.9±0.024×10 −3 mm 2 /s) were significantly higher than those for MCNs (mean 2.1±0.30×10 −3 mm 2 /s). ROC analysis showed an optimal cut-off value of 2.4×10 −3 mm 2 /s for differentiating between the two types of lesions, providing a sensitivity of 98% and a specificity of 88%. Conclusion The results of the present study suggest that ADC values in mucinous cystic lesions of the pancreas can be advantageous for their characterization into IPMN and MCN.