Intraductal papillary mucinous neoplasm of the pancreas: assessment of the likelihood of invasiveness with multisection CT.

PURPOSE: To evaluate the capabilities of multisection computed tomography (CT) in determining the likelihood of invasiveness of intraductal papillary mucinous neoplasm (IPMN). MATERIALS AND METHODS: The institutional review board approved this research and waived informed consent from the patients. Two radiologists blinded to the pathologic assessment of malignancy or parenchymal invasion of IPMN retrospectively evaluated CT images of 61 consecutive surgically resected tumors (26 adenomas, 15 noninvasive carcinomas, and 20 invasive carcinomas) in patients who underwent multiphase contrast material-enhanced CT with 0.5- or 1-mm collimation. The findings were statistically analyzed by using univariate and multivariate analyses, with the optimal cutoff levels of each continuous parameter determined by generating receiver operating characteristic curves. RESULTS: The following findings showed significant differences among the three groups: maximum diameter of the main pancreatic duct (MPD), size (length of major axis) of the largest mural nodule in the MPD or in any associated cystic lesion, abnormal attenuating area in the surrounding parenchyma, calcification in the lesion, protrusion of the MPD into the ampulla of Vater, and bile duct dilatation. An MPD diameter of 6 mm or larger, a mural nodule of 3 mm or larger, and an abnormal attenuating area were independently predictive of malignancy. A mural nodule of 6.3 mm or larger in the MPD and an abnormal attenuating area were independently predictive of parenchymal invasion. According to these criteria, the sensitivity, specificity, and accuracy for identifying malignancy were 83%, 81%, and 82% and for identifying parenchymal invasion were 90%, 88%, and 89%, respectively. CONCLUSION: Multisection CT is useful for distinguishing among adenoma, noninvasive carcinoma, and invasive carcinoma in patients with IPMN.