The Role of ¹⁸F-fluoro-d-deoxyglucose PET/CT in the Diagnosis of Post-operative Hardware Related Spinal Infections

Background: Implant-related spinal infections are a devastating complication associated with high morbidity. The insidious nature of some of the infections may delay the diagnosis until the infection had spread and dictate hardware removal which can result is pseudarthrosis and the loss of stability and alignment.

Objective: To evaluate the accuracy and diagnostic value of 18-FDG PET/CT in the work-up of patients with suspected implant-related infections of the spine, and to assess the clinical impact of PET/CT result on the management of these infections.

Methods: Nine consecutive patients with a history of previous spinal surgery who underwent PET/CT for evaluation of a suspected spinal implant related infection were included. All imaging studies were performed between 01.2011 and 12.2013. All 18F-FDG PET/CT scans were performed on an 8 slice PET/CT (Discovery STE, General Electric). Image Acquisition started 60–90 min after [18F]-FDG Injection (296–555 MBq) on Limited diagnostic quality helical CT (120 kV, modulated 80–280 mAs, 2.5 mm slice thickness, 0.875 pitch). Images were scored visually and semiquantitatively by a radiology expert. Results were compared to additional imaging studies, when available and correlated to clinical and bacteriological findings allowing calculation of sensitivity, specificity and accuracy.

Results. Five patients had hardware related spinal infection. Sensitivity was 80%, specificity 100% and accuracy 88.9%. For the false negative case, a second later PET/CT scan was indicative for infection.

Conclusion: PET/CT was found to be of high value in the diagnosis of post-operative hardware related spinal infection, especially when other imaging modalities were uninformative or inconclusive. It could be a useful tool in directing further treatment.