Factors Predicting Positive Culture in CT-Guided Bone Biopsy Performed for Suspected Osteomyelitis

OBJECTIVE. The goal of this study was to identify clinical factors and radiographic characteristics associated with positive culture results from bone biopsy in cases of suspected osteomyelitis. MATERIALS AND METHODS. A total of 997 CT-guided bone biopsies were reviewed. We reviewed the images and medical records of 29 cases of suspected osteomyelitis to determine if any of the following factors affected culture results: age, sex, history of diabetes, collection of fluid aspirate at the time of biopsy, recent antibiotic therapy, elevated WBC count, and mean attenuation. RESULTS. Of the 29 CT-guided bone biopsies, 21% yielded positive culture results. We found no significant difference in age, sex, history of diabetes, collection of fluid aspirate at the time of biopsy, recent antibiotic therapy, or elevated WBC count between positive culture and negative culture cases. We did, however, find a significant difference in the mean CT attenuation values of the sampled bone between the two groups: 72.0 +/- 41.5 HU (95% CI, 28.4-115.6 HU) among the positive culture group compared with 227.5 +/- 198.8 HU (95% CI, 141.4-313.6 HU) among the negative culture group (p = 0.03). CONCLUSION. The rate of positive culture from image-guided core biopsy of suspected osteomyelitis is low. In this study, lower CT attenuation values were associated with a significantly higher rate of positive culture. An attenuation value of 150 HU may serve as a threshold above which biopsy would be expected to have lower utility for obtaining specific microbial culture data.