Volumetric and morphological analysis of intraductal papillary mucinous neoplasm of the pancreas using computed tomography and magnetic resonance imaging.

OBJECTIVE: The purpose of this study was to predict the malignancy of intraductal papillary mucinous neoplasm (IPMN) based on data obtained by computed tomography and magnetic resonance imaging.

METHODS: Sixty-nine patients with IPMN underwent computed tomography, magnetic resonance imaging, and surgery. The tumors were classified pathologically as IPMN (adenoma), IPMN (in situ carcinoma), and invasive carcinoma derived from IPMN, and analyzed morphologically for the following characteristics: tumor size, main pancreatic duct (MPD) diameter, tumor area, MPD area, tumor volume, MPD volume, and intraductal volume (tumors volume + MPD volume).

RESULTS: Main pancreatic duct diameter (P = 0.017) and intraductal volume (P = 0.0013) showed significant differences among IPMN (adenoma), IPMN (in situ carcinoma), and invasive carcinoma derived from IPMN. When IPMN (in situ carcinoma) and invasive carcinoma derived from IPMN were classified as malignant IPMN, an MPD diameter of 6 mm or more and an intraductal volume of 10 cm or more were set as cutoff levels predictive of malignancy using receiver operating characteristic curve analysis. On the basis of these criteria, the sensitivity and specificity for identifying malignancy in MPD were 83% and 59%, and those for intraductal volume were 70% and 73%, respectively.

CONCLUSION: Intraductal volume (≥10 cm) determined by volumetric analysis is useful for diagnosis of malignant IPMN.