Vascular encasement by pancreatic cancer: Correlation of CT findings with surgical and pathologic results

Purpose: The purpose of this study was to correlate thin-slice high-resolution helical CT findings of arterial and venous involvement in pancreatic cancers with surgical and histopathologic results. Method: Forty-eight patients with pancreatic cancer underwent preoperative thin-slice high-resolution helical CT, followed by surgical dissection of the pancreatic vessels during curative or palliative surgery. Major vessels running within 1 cm from the tumor margin were evaluated. CT appearance was graded on a 0-4 scale (0: none, 1: < 24%, 2: 25-49%, 3: 50-74%, 4: 75-100%) by circumferential contiguity of tumor to vessels. Resected specimens were available from 26 patients. Results: Surgical correlation of CT findings was available in 89 veins and 83 arteries, and both surgical and histologic col-relation was available for 42 veins and 29 arteries. At surgical observation, 29 of 35 veins (82.9%) evaluated as CT grade 3 or 3 were found to be involved, whereas only 18 of 30 arteries (60%) evaluated as CT grade 3 or 3 were proved to be involved, On microscopic observation, tumor invasion to the portal venous systems was confirmed in 15 of 42 (35.7%) vessels, and this invasion was depicted as from CT grades 1 to 4. In arteries, tumor invasion was seen in 3 of 29 vessels (10.3%), all of which were graded as 3 or 3 by CT. Conclusion: The grading system of vascular invasion should differ between arteries and veins. Involvement of the venous system exceeding one-half circumference of the vessels (grade 3 or 3) was suggestive of vascular invasion; however, this criterion was not always satisfactory fur the evaluation of tumor invasion in the arterial system.