Invasive carcinomas originating from intraductal papillary mucinous neoplasms of the pancreas: conspicuity and primary sites of the solid masses on triple-phase dynamic CT imaging

To assess the conspicuity of invasive carcinomas (solid masses) originating from pancreatic intraductal papillary mucinous neoplasms (invasive IPMNs) and the primary sites of the solid masses on thin-slice dynamic CT. Twenty patients with pathologically proven invasive IPMNs underwent triple-phase dynamic CT examinations (arterial, portal, and delayed phases). Qualitative and quantitative analyses of conspicuity of the solid masses were performed for all phases. The primary sites [branch duct and/or main pancreatic duct (MPD)] of the solid masses were evaluated on CT in comparison to the pathologic findings. The qualitative and quantitative analyses of the conspicuity of the solid masses showed that the arterial phase images were superior to those of the portal and delayed phases. The primary sites of the solid mass were histopathologically diagnosed as branch ducts in 6 (30%) patients, MPD in 13 (65%), and both branch ducts and the MPD in one (5%). The sensitivity and specificity of the CT evaluation of the primary sites were 100% for the branch ducts, and for the MPD 93% and 100%, respectively. Arterial phase images are useful for the diagnosis of invasive IPMNs, and attention should be paid to pancreatic parenchyma surrounding the MPD when detecting invasive carcinomas.