Indium-111-labeled white blood cells in the detection of osteomyelitis complicated by a pre-existing condition.

Forty-six patients (23M, 23F) ranging in age from 19 to 79 yr with a clinical history of a nonunion fracture, surgery, diabetes or a soft-tissue infection were studied with [111In]oxine WBCs to detect osteomyelitis. There were 27 true-positive, nine true-negative, two false-positive and one false-negative. The false-positives and the false-negative occurred in patients with soft-tissue infections overlying the area of interest. All diagnoses were confirmed by intraoperative bone biopsies and cultures. Bone biopsy and scan were performed within 2 days of each other in 39 patients. The overall sensitivity was 97% (27/28), specificity, 82% (9/11) and the diagnostic accuracy, 92% (36/39). The remaining seven patients had negative [111In]WBC scans several months after positive bone biopsies and definite antibiotic treatment. This suggests that [In]WBC scans become negative after appropriate therapy is undertaken. Interobserver data was obtained from four nuclear physicians of varying experience blinded to clinical information. A high degree of agreement was found in over 90% of the cases. This study demonstrates the utility of [111In]WBC scans in the diagnosis and follow-up of complicated osteomyelitis and a high level of interobserver agreement in scan interpretation.