Intraductal papillary mucinous tumors of the pancreas: Thin-section helical CT findings

OBJECTIVE, The purpose of this study was to evaluate the thin-section helic al CT findings of intraductal papillary mucinous tumors and to investigate whether helical CT could distinguish between malignant and benign intraduct al papillary mucinous tumors. MATERIALS AND METHODS. Twenty-seven patients (nine with malignant and 18 wi th benign intraductal papillary-mucinous tumors) underwent thin-section (3- or 5-mm) helical CT. Two-phase enhanced CT was started 30 and 60-70 sec af ter injection of contrast material at 3 ml/sec. RESULTS. In six patients (22.2%), a bulging papilla was depicted on CT. Twe nty-five patients (92.6%) had a dilated main pancreatic duct. Cystic lesion s were seen in 25 patients (92.6%). Thirteen lesions (48%) were located in the uncinate process, seven (25.9%) were in the head, two (7.4%) were in th e body, and three (11%) were in the tail. The cystic lesion was unilocular in five patients (18.5%) and multilocular with a lobulated margin in 20 pat ients (74%). Communication between the main pancreatic duct and the cystic lesion was depicted in 19 patients (70.4%). The papillary projections corre sponding to 3-mm or larger papillary neoplasms were depicted in five patien ts (18.5%). The bulging papilla was more often observed in malignant than i n benign intraductal papillary mucinous tumors (p < 0.05). The caliber of t he main pancreatic duct was significantly larger in patients with malignant intraductal papillary mucinous tumors (p > 0.001). CONCLUSION. The most frequently found feature of intraductal papillary muci nous tumors was a lobulated multilocular cystic lesion located in the uncin ate process and in contiguity with the dilated main pancreatic duct. In som e patients, a bulging papilla and papillary projections in the ducts, which were specific findings, were visualized on CT. The bulging papilla and the caliber of the main pancreatic duct helped differentiate malignant from be nign intraductal papillary mucinous tumors.