Localizing infection with a technetium-99m-labeled peptide: initial results

In vitro-labeled leukocyte imaging is useful for the detection of infection , but an in vivo labeling method is preferable. This study sought to evalua te the safety and efficacy of a leukocyte-avid peptide for the detection of infection, to determine the effects of peptide dose on performance and to compare the peptide with in vitro-labeled leukocytes. A 23-amino acid pepti de, P483, containing the platelet factor-4 heparin-binding sequence, was la beled with Tc-99m and complexed with heparin (P483H). Thirty patients were injected with 29 mug (n = 11), 145 mug (n = 10) or 290 mug (n = 9) of label ed peptide, and imaged 15 min and 90-120 min later. Early and late images w ere interpreted individually and jointly. Twenty patients underwent In-111- labeled leukocyte scintigraphy. Fourteen patients had infection: osteomyeli tis (n = 7), vascular graft (n = 2), abscess (n = 2), joint replacement (n = 1), surgical wound (n = 1) and pneumonia (n = 1). There were 10 adverse e vents in six patients; all were mild and resolved spontaneously, and withou t any intervention. The sensitivity, specificity and accuracy were the same for both early and late imaging: 0.86, 0.81 and 0.83, respectively. Interp reting early and late images together did not improve the results. No relat ionship between peptide dose and study accuracy was found. In patients unde rgoing both examinations, the accuracies of the peptide and in vitro-labele d leukocyte imaging were identical: 0.80. In summary, Tc-99m-P483H safely, rapidly and accurately detected focal infection, was comparable with in vit ro-labeled leukocyte imaging and therefore merits further investigation. (( C) 2001 Lippincott Williams & Wilkins).