LOCAL STAGING OF PANCREATIC-CANCER - CRITERIA FOR UNRESECTABILITY OF MAJOR VESSELS AS REVEALED BY PANCREATIC-PHASE, THIN-SECTION HELICAL CT

OBJECTIVE. This study was conducted to determine the criteria for unre sectability of major peripancreatic vessels in patients with pancreati c carcinoma as revealed by optimally enhanced, pancreatic-phase thin-s ection helical CT. SUBJECTS AND METHODS. Twenty-five patients with pan creatic adenocarcinoma who underwent local dissection during curative or palliative surgery also underwent preoperative pancreatic-phase thi n-section helical CT (40- to 70-sec delay, 2.5- to 3-mm collimation). Tumor involvement of the portal and superior mesenteric veins and the celiac, hepatic, and superior mesenteric arteries was prospectively gr aded on a 0-4 scale based on circumferential contiguity of tumor to ve ssel. Subsequent surgical results were then correlated with the CT gra des. RESULTS. At surgery, definitive evaluation was possible for 80 ve ssels. Forty-eight of 48 vessels graded 0 and three of three vessels g raded 1 were resectable. Four of seven vessels graded 2, seven of eigh t vessels graded 3, and 14 of 14 vessels graded 4 were unresectable. A threshold of between grades 2 and 3, which corresponded to tumor invo lvement of one-half circumference of the vessel, yielded the lowest nu mber of false-negatives and an acceptable number of false-positives fo r unresectability. Such a threshold would have yielded a sensitivity o f 84%, a specificity of 98%, a positive predictive value of 95%, and a negative predictive value of 93% for unresectability of the vessels s tudied.CONCLUSION. A grading system for tumor involvement of the major vessels in patients with pancreatic adenocarcinoma can be based on th e degree of circumferential contiguity of tumor to vessel. Involvement of vessel to tumor that exceeds one-half circumference of the vessel is highly specific for unresectable tumor.