Objective: To study and compare the accuracy and sensitivity of endoscopic ultrasonography (EUS) and CT scaning in determination of preoperative stage and vascular invasion by pancreatic and ampullary cancers.

Methods: Fourty-two pancreatic cancer patients and 18 ampullary cancer patients were studied. With patients prepared according to conventional endoscopy, Olympus EUM-30 scope 1 set with a side view and 360 degrees rotate and switchable scanning probe [ultrasound frequency (7.5/12 MHz)], was introduced to the descending duodenum through the esophagus. Gas within the duodenum and stomach was aspirated. Then, in order to to facilitate ultrasound transmission, 200 ml deaerated water was injected into the duodenum and 500 ml into the stomach to distend it. The structures of each part of pancreatic head and ampullary together with surrounding vessels were scanned. Then, the scope was withdrawn to the gastric antrum, body and fundus gradually, while the pancreatic body and tail were scanned.

Results: Between Apr. 1996 to May 2004, a total of 42 pancreatic cancer patients and 18 ampullary cancer patients were examined by EUS. Meanwhile, all these 58 patients received preoperative CT scaning. The results of stage and vascular invasion determined by EUS in this series were as following; pancreatic cancer group (n = 42): accuracy in T2-4 stage was 100.0% (5/5), 75.0% (9/12) and 48.0% (12/25), respectively; ampullary cancer group (n = 18): T1-4 stage was 75.0% (3/4), 66.7% (2/3), 75.0% (6/8) and 33.3% (1/3), respectively; the accuracy in N stage: P-group: 80.0% in N1 (4/5), 90.0% in N0 (9/10); A-group: 50.0% in N1 (3/6), 91.0% in N0 (10/11). The sensitivity, specificity of vascular invasion, resectability and unresectablilty determined by EUS and CT as compared with surgical findings during operation was 52.9% (9/17), 93.1% (27/29), 77.1% (27/35) and 81.8% (9/11) for EUS (n = 60), respectively; and 11.8% (2/17), 92.6% (25/27), 62.5% (25/40) and 50.0% (2/4) for CT (n = 58), respectively.

Conclusion: Endoscopic ultrosonography being one of the best image examinations to determine the stage and vascular invasion for pancreatic and ampullary cancer paitients is able to detect small pancreatic or ampullary cancer less than 2.0 cm in diameter due to its high resolution; but can not detect the secondary multiple distal metastases such as spread into the liver, peritonium or hepatoduodenal ligament, etc. due to its ultrasound depth limitation.