Fluorine-18-FDG PET and technetium-99m antigranulocyte antibody scintigraphy in chronic osteomyelitis

The aim of this study was to assess the usefulness of PET with 2-F-18-fluor o-2-deoxy-D-glucose (FDG), as compared to immunoscintigraphy (IS) with Tc-9 9m-labeled monoclonal antigranulocyte antibodies (AGAbs), in the detection of chronic osteomyelitis. Methods: Fifty-one patients suspected of having c hronic osteomyelitis in the peripheral (n = 36) or central (n = 15) skeleto n were evaluated prospectively with static FDG PET imaging and combined Tc- 99m-AGAb/Tc-99m-methylene diphosphonate (MDP) bone scanning within 5 days. FDG PET and IS were evaluated in a blinded and independent manner by visual interpretation, which was graded on a five-point scale of two observers' c onfident diagnosis of osteomyelitis. Receiver operating characteristic (ROC ) curve analysis was performed for both imaging modalities. The final diagn osis was established by means of bacteriologic culture of surgical specimen s and histopathologic analysis (n = 31) or by biopsy and clinical follow-up over 2 yr (n = 20). Results: Of 51 patients, 28 had osteomyelitis and 23 d id not. According to the unanimous evaluation of both readers, FDG PET corr ectly identified 27 of the 28 positives and 22 of the 23 negatives (IS iden tified 15 of 28 positives and 17 of 23 negatives, respectively). The area u nder the ROC curve was 0.97/0.97 (reader 1/reader 2) for FDG PET and 0.87/0 .90 for IS, with a high degree of interobserver concordance (kappa-values w ere 0.96 for FDG PET and 0.91 for IS). In the central skeleton, the ROC cur ve area was 0.98/1.00 for FDG PET and 0.71/0.77 for IS (p < 0.05). On the b asis of ROC analysis, the overall accuracies of FDG PET and IS in the detec tion of chronic osteomyelitis were 96%/96% and 82%/88%, respectively. With regard to the optimal threshold values, sensitivity and specificity were 10 0%/97% and 95%/95% with FDG PET, compared to 86%/92% and 77%/82% with IS, r espectively. Conclusion: In the peripheral skeleton, both FDG PET and combi ned Tc-99m-AGAb/(TC)-T-99m-MDP scanning are appropriate imaging modalities to diagnose chronic osteomyelitis. FDG PET additionally allows reliable dif ferentiation between osteomyelitis and infection of the surrounding soft ti ssue. In the central skeleton within active bone marrow, FDG PET is highly accurate and superior to AGAb imaging in the diagnosis of chronic osteomyel itis, which frequently presents as a nonspecific photopenic lesion at scint igraphy with labeled white blood cells.