DETECTION OF PELVIC RECURRENCE OF COLORECTAL-CARCINOMA - PROSPECTIVE,BLINDED COMPARISON OF TC-99M-IMMU-4 MONOCLONAL-ANTIBODY SCANNING AND CT

PURPOSE: To prospectively compare the accuracy of imaging with technet ium-99m-labeled Fab' fragment of the anti-carcinoembryonic antigen ant ibody (CEA) IMMU-4 with that of computed tomography (CT) for the detec tion of pelvic recurrence of colorectal carcinoma. MATERIALS AND METHO DS: In 61 patients, blinded interpretations of both modalities were co rrelated with surgical-pathologic (n = 23) or clinical and CT follow-u p findings (n = 38). RESULTS: Sensitivity and specificity with antibod y scanning alone and combined with CT (79% and 84% vs 83% and 81%, res pectively) were not significantly different from those values for CT a lone (66% and 97%, respectively). Sensitivity of antibody scanning was greater for recurrences larger than 2 cm (94% vs 55% [P = .02]), seru m CEA more than 2.5 ng/mL (91% vs 40% [P = .03]), and combined planar and single photon emission CT antibody scanning compared with planar a lone (79% vs 48% [P = .03]), without a significant decrease in specifi city. CONCLUSION: Antibody scanning does not improve on findings at CT alone for recurrent colorectal carcinoma but can help differentiate r ecurrent tumor from fibrosis.