Use of tc-99m HMPAO leukocyte scans to evaluate bone infection - Incremental value of additional SPECT images

Purpose: In this study, the diagnostic value of Tc-99m hexamethylpropylene amine oxime (HMPAO) leukocyte scans and the role of additional SPECT in the diagnosis of bone infection were evaluated. Materials and Methods: The Tc-99m HMPAO leukocyte scans of 37 patients with clinically suspected bone infection were reviewed. The patients were divid ed into two groups according to the presence of orthopedic implants. Early (4 to 6 hours) and delayed (18 to 20 hours) planar images and early SPECT i mages were obtained. The final diagnosis of infection was made based on the pathologic, bacteriologic, and surgical data and clinical follow-up. Results: Group 1 (25 patients with orthopedic implants) included 15 true-po sitive, 1 false-negative, 7 true-negative, and 2 false-positive results. Gr oup 2 (12 patients without orthopedic implants) included 7 true-positive, 1 false-negative, and 4 true-negative results. The overall sensitivity of th e Tc-99m HMPAO leukocyte scan with SPECT to detect bone infection was 92%, with a specificity rate of 85%. (Group 1: sensitivity, 94%; specificity, 78 %, Group 2: 88% and 100% sensitivity and specificity, respectively.) Conclusion: The Tc-99m HMPAO leukocyte scan is useful in the diagnosis of b one infection, regardless of the presence of orthopedic implants. The addit ional SPECT images may be helpful to localize the site of infection more ac curately.