Diagnosis of Pedal Osteomyelitis in Diabetic Patients Using Current Scintigraphic Techniques

TLDR

Seventy‑seven diabetic patients with suspected foot osteomyelitis were evaluated by three‑phase bone scintigraphy, indium‑111 labeled white‑blood‑cell scintigraphy, roentgenography, or combinations thereof. TPBS alone had 100 % sensitivity but only 38 % specificity, WBCS alone had 100 % sensitivity and 78 % specificity, combining TPBS and WBCS did not improve specificity beyond 79 %, and roentgenography yielded 69 % sensitivity and 82 % specificity, leading the authors to conclude that WBCS alone is sufficient for diagnosing pedal osteomyelitis, especially in the tarsometatarsal region. Published in Arch Intern Med 1989;149:2262‑2266.

Abstract

• Seventy-seven diabetic patients with suspected osteomyelitis of the foot were evaluated by three-phase bone scintigraphy (TPBS), indium 111–labeled white blood cell scintigraphy (WBCS), roentgenography, or some combination thereof. Retrospective analysis after clinical and pathologic follow-up indicated that the sensitivity of TPBS alone in the diagnosis of osteomyelitis was 100%, with a specificity of only 38% and an accuracy of 63%; the sensitivity of WBCS alone was 100%, with a specificity of 78% and an accuracy of 87%; and the combination of TPBS and WBCS yielded a sensitivity of 100%, with a specificity of 79% and an accuracy of 87%. Roentgenography yielded a sensitivity of 69%, with a specificity of 82% and an accuracy of 76%. The results of this study demonstrate that WBCS is superior to TPBS in the diagnosis of osteomyelitis in the diabetic foot, and TPBS adds little when viewed in conjunction with WBCS. Based on our observations and because of the high prevalence of neuropathic joint disease and other causes of false-positive bone scans, we believe that WBCS alone is adequate for evaluation of suspected pedal osteomyelitis in diabetic patients, particularly when the suspected lesion is located in the tarsometatarsal region in contrast to the toe region (7% vs 44% specificity and 28% vs 69% accuracy, respectively, for TPBS in these two regions, compared with 100% vs 68% specificity and 100% vs 80% accuracy, respectively, for WBCS in the same two regions). (<i>Arch Intern Med</i>. 1989;149:2262-2266)