Abstract
Objective
18F-fluorodeoxyglucose-PET/CT is the imaging modality of choice for the diagnosis of postoperative spine infection. Published interpretation criteria are variable and often incompletely described. The objective was to develop a practical and standardized approach.
Materials and methods
Two-hundred-twenty-seven FDG-PET/CTs performed on 140 postoperative patients over a 7-year period were reviewed retrospectively. The presence or absence of infection was determined from clinical history, microbiology, other investigations, and clinical outcome during a minimum 6-month follow-up.
Results
No activity attributable to normal healing was seen in the post-discectomy space or at the bone-hardware interface in the absence of a complication at any stage. Within the incision, activity from normal healing persisted for months. Wound infections were diagnosed clinically, and most had already been treated before FDG-PET/CT was done to assess deep structures.
With proven infection, 95% of cases had activity in bone or soft tissue outside the surgical field. The remaining 5% had activity confined to the post-discectomy space. Sterile hardware loosening may cause elevated activity which remains confined to the bone/hardware interface.
Pathogens are introduced directly at the time of surgery and may be avirulent resulting in indolent infection with low-grade activity. At the same time, activity from non-infectious causes can be intense. A semi-quantitative method using SUVmax performed poorly compared with assessment of the distribution of activity.
Conclusion
These observations have been incorporated into a checklist which is now being used at the time of interpretation. The potential sensitivity and specificity in the diagnosis of infection are close to 100%.
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Kloiber, R., Lafford, H., Koslowsky, I.L. et al. A practical approach to interpretation of 18F-fluorodeoxyglucose positron emission tomography/computed tomography for postoperative spine infection. Skeletal Radiol 53, 741–752 (2024). https://doi.org/10.1007/s00256-023-04474-6
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DOI: https://doi.org/10.1007/s00256-023-04474-6