Pancreatic mucinous cystoadenomas and cystoadenocarcinomas: differential diagnosis by means of MRI

Objective: To determine the accuracy of MRI in differentiating mucinous cystoadenomas (MCAs) from mucinous cystoadenocarcinomas (MCACs) of the pancreas, with histopathological analysis as the reference standard, for better surgical planning. Methods: A total of 65 patients with histopathologically proven mucinous cystic neoplasms (MCNs) underwent MRI and surgery. Quantitative image analysis included size, septa and wall thickness and number of loculations. Qualitative image analysis included nodules; hyperintensity of the cystic content on T-1 weighted images; compression and/or infiltration of adjacent vessels or organs; and metastases. A comparison between MCAs and MCACs was performed with Student's t-test for quantitative variables and with Fisher test for qualitative variables. Receiver operating characteristic analysis was performed to determine the accuracy in the differential diagnosis between MCAs and MCACs on the basis of a score system obtained by giving 1 point for each quantitative and qualitative variable observed in each patient. Results: At histopathology, 43 lesions were MCAs and 22 lesions were MCACs. A statistically significant difference was observed for size >7cm (<0.001), septa and wall thickness >3mm (<0.0001), number of loculations >4 (<0.0001), nodules (<0.0001), hyperintensity of the cystic content on T-1 weighted images (<0.0001), compression (<0.01) and/or infiltration (<0.01) of adjacent vessels or organs and metastases (<0.05). The best cutoff value to discriminate MCAs from MCACs was the presence of three features (p<0.001), with an accuracy of 91%. Conclusion: MRI has an accuracy of 91% in the differential diagnosis between MCA and MCAC, helping in identifying forms that could undergo parenchyma-sparing surgery (MCAs), reducing post-surgical morbidity and mortality. Advances in knowledge: In this study, the differentiation between MCAs and MCACs of the pancreas by means of MRI is addressed. The differential diagnosis allows selecting benign forms, susceptible of parenchyma-sparing surgery, with the advantage of reducing post-surgicalmorbidity and stratifying prognosis of MCNs.