Multi-detector spiral CT diagnosis of common bile duct ampullary carcinoma.

OBJECTIVE: The aim of this project was to study the imaging characteristics of multi-detector CT (MDCT) in different types of malignant tumor in the common bile duct ampulla.

PATIENTS AND METHODS: We examined 30 cases of pancreatic head cancer, 35 of terminal cholangiocarcinoma, 26 of ampullary carcinoma, and 40 of benign lesions, all confirmed by pathology. We used 64-slice spiral CT plain scan and multi-phase enhanced scan with multi-planar reconstruction (MPR) and curved planar reconstruction (CPR) post-processing to obtain three-dimensional images. From these images, we analyzed intrahepatic and extrahepatic bile ducts, gallbladder and common bile duct dilation, and morphology and enhancement pattern of lesions and surrounding tissue.

RESULTS: The dilatation rate of intrahepatic, extrahepatic bile duct and gallbladder in terminal cholangiocarcinoma was the highest. The double duct sign was most evident in pancreatic head cancer. Ampullary carcinoma fell in between, and the benign lesions had no intrahepatic or extrahepatic bile duct and pancreatic duct dilation. Pancreatic cancer had a larger diameter, a higher internal rate of necrosis, and the surrounding tissues had a higher vulnerability to invasion. Terminal cholangiocarcinoma had a smaller diameter and a thicker wall. Benign lesions showed isodensity and hyperdensity shadow in the lumen, but no other significant changes were observed. Pancreatic head carcinoma had lower enhancement degree than normal pancreatic tissue, no enhancement in the internal necrotic area, and the borderline was unclear. Thickened ductal wall of the terminal cholangiocarcinoma showed equal density, enhancement and commonly delayed enhancement. The enhancement degree was higher than in the cancer of the pancreatic head and slightly lower than in ampullary cancer. Ampullary cancer had a regular margin and a significant enhancement, with enhancement degree higher than in pancreatic cancer and lower than in common bile duct cancer. Arterial and venous phases showed enhancement, but benign lesions did not show enhancement.

CONCLUSIONS: MDCT imaging and post-processing techniques have significant application in the diagnosis of benign and malignant lesions, as well as a malignant tumor of the common bile duct ampulla.