Clinical significance of intraductal ultrasonography (IDUS) for intraductal papillary tumor of the pancreas in comparison whth other imaging modalities

Conventional ultrasonography (US), abdominal computed tomography (CT), endoscopic ultrasonography (EUS) and intraductal ultrasonography (IDUS) were performed for 23 cases of intraductal papillary tumor (IDT) of the pancreas. On the basis of the histopathological analysis of 28 cases of resected IDT, criterion for differential diagnosis by imaging modalities was defined as follows : hyperplasia lucking wall thickening or nodule, adenoma having a nodule or wall thickening under 3mm, intraductal cancer having a nodule or wall thickening over 4mm, or a cyst filled with tumor, intraductal cancer with pancreatic parenchymal invasion having a mass with a mixed patterns (high and low internal echo patterns) or interruption of the pancreatic duct wall by tumor invasion. With this criterion, US and CT showed high specificity, but low sensitivity in the differential diagnosis of IDT. However, EUS and IDUS revealed high sensitivity and diagnostic accuracy for the differential diagnosis of neoplastic and non-neoplastic lesions. They also showed high diagnostic accuracy for differential diagnosis of benign and malignant tumors, and invasive and non-invasive lesions. Thus EUS and IDUS are considered to contribute much to the choice of the treatment of the IDT.