In-111 labeled purified granulocytes in the diagnosis of synthetic vascular graft infections

Indium-111 labeled enriched granulocytes should have improved accuracy in diagnosing synthetic vascular graft infections compared to labeled mixed leukocyte preparations because of the reduced numbers of reinjected erythrocytes and platelets, thereby reducing blood pool and nonspecific platelet adhesion to the graft. To test the use of enriched granulocytes in the diagnosis of vascular graft infections, the authors reviewed 153 studies in 106 patients. All were imaged with In-111 oxine labeled enriched autologous granulocytes prepared using Volex (American Critical Care, McGaw Park, IL) enhanced gravity sedimentation and Ficoll-Hypaque (Pharmacia Biotech, Piscataway, NJ; Winthrop Pharmaceuticals, New York, NY) double density centrifugation. The diagnosis of infection was established or refuted based on operative appearance of infection in one third of patients, and the clinical course over a mean 10-month follow-up period in the remainder. Of those patients with infection, 29 of 43 had positive imaging results that yielded a sensitivity of 67%. Of 100 patients without infection, 97 had negative imaging results that yielded a specificity of 97%. Compared to pooled data of studies using In-111 oxine labeled mixed leukocyte preparations, the sensitivity of enriched granulocytes appears lower and the specificity higher. The apparent reduced sensitivity may relate to the chronic nature of some graft infections and the markedly reduced number of reinjected lymphocytes in enriched granulocyte preparations compared to mixed leukocyte preparations. Although the specificity is very high using enriched granulocyte preparations, there may not be a significant advantage of the method over mixed leukocyte preparations.