Evaluation of the utility of indium-111 oxine platelet imaging in renal transplant patients on cyclosporine.

Twenty five In-111 oxine platelet imaging procedures were performed in 21 renal transplant patients to assess the value of this study for diagnosis of renal transplant rejection in recipients receiving cyclosporine (CYS) for immunosuppression. Fourteen biopsies were performed, and an extensive, in-depth review of the clinical progress of each patient was obtained. There was no ideal "gold standard" to which our imaging results could be compared, but we used a combination of biopsy findings, clinical impressions, and changes in renal function after pulsing with steroids and/or decreasing CYS dosage as the basis for our diagnoses. We were unable to distinguish between renal rejection and CYS toxicity using platelet imaging. The sensitivity of the platelet procedure for diagnosing rejection or CYS toxicity was 100%. The specificity for rejection or CYS toxicity was only 76.5%. In view of the inability of this test to distinguish between rejection and CYS toxicity, its rather low specificity, and its relatively high cost, it is not a particularly helpful study for the diagnosis of renal transplant rejection in patients on CYS.