CT pancreatogram in carcinoma of the pancreas and chronic pancreatitis.

CT has made it possible to determine the contour of the pancreatic duct, to measure its caliber, and to detect dilatation of the duct. CT scans of 75 patients with pancreatic carcinoma and of 45 patients with chronic pancreatitis were obtained. Dilatation of the pancreatic duct was seen in 56% of patients with carcinoma, and in 70% of those with tumors confined to the pancreatic head and body. Smooth dilatation (43%) or beaded dilatation (40%) were most commonly associated with carcinoma. Ductal dilatation was present in 58% of the patients with chronic pancreatitis, and irregular dilatation was seen in 73% of the patients in this group. About half of the patients who had irregular dilatation had calculi within the ducts. The duct contour was similar to that seen in carcinoma in 27% of the cases of chronic pancreatitis. There was a significant difference in the caliber of the duct (P = .01) with larger ducts seen in patients with carcinoma. The width of the pancreatic gland (P = .005) and the ratio of duct caliber to gland width differed (P = .001) between the two diseases: the gland was wider in cases of chronic pancreatitis, and the ratio of duct to gland was larger in cases of carcinoma. Eight cases of dilatation of the duct with no detectible pancreatic mass were seen in a subgroup of 13 patients who had small carcinomas of the pancreas (tumor size of 3 cm or less). Our findings indicate that a dilated pancreatic duct with a smooth contour and a ratio of duct to total gland width of 0.50 or greater suggests carcinoma as the underlying pathology.