Prospective comparison of whole-body (18)F-FDG PET/CT and MRI of the spine in the diagnosis of haematogenous spondylodiscitis.

PURPOSE: To prospectively compare (18)F-FDG PET/CT and MRI in the diagnosis of haematogenous spondylodiscitis METHODS: The study included 26 patients (12 women, 14 men; mean age 59 ± 17 years) with clinical symptoms of infection of the spine. Patients who had had prior spinal surgery or any type of antibiotic therapy in the previous 3 months were excluded from the study. Whole-body PET/CT 60 min after injection of 4.07 MBq/kg of (18)F-FDG and an MRI scan of the spine was performed in all patients. SUVmax in an area surrounding the lesions with the suspicion of infection as well as a background SUVmean in a preserved area of the spine were calculated for quantification. Infection was diagnosed by microbiological documentation in cultures of image-guided spinal puncture fluid or blood. Infection was excluded if symptoms were absent without antimicrobial therapy during a follow-up of at least 6 months. RESULTS: Spondylodiscitis was confirmed in 18 of the 26 patients. Staphylococcus aureus was found in 8 patients, Mycobacterium tuberculosis in 4, Escherichia coli in 2 and other pathogens in 4. Of the remaining 8 patients, the diagnoses were degenerative spondyloarthropathy in 5 and vertebral fracture in 3. The sensitivity, specificity, and positive and negative predictive value were 83%, 88%, 94% and 70% for (18)F-FDG PET/CT, and 94%, 38%, 77% and 75% for MRI, respectively. The accuracies of (18)F-FDG PET/CT and MRI were similar (84% and 81%, respectively). The combination of (18)F-FDG PET/CT and MRI detected the infection in 100% of the patients with spondylodiscitis. (18)F-FDG uptake, quantified in terms of SUVmax corrected by the background SUVmean, was significantly higher in patients with spondylodiscitis than in those without infection (p < 0.001). CONCLUSION: Due to its high specificity, (18)F-FDG PET/CT should be considered as a first-line imaging procedure in the diagnosis of spondylodiscitis. Quantification of uptake in terms of SUVmax was able to discriminate infection of the spine from other processes in this series of patients.

A prospective study comparing whole-body FDG PET/CT to combined planar bone scan with 67Ga SPECT/CT in the Diagnosis of Spondylodiskitis.

PURPOSE: This study aimed to prospectively evaluate the usefulness of PET/CT using F-FDG in comparison to bone scan and Ga in the diagnosis of spondylodiskitis. MATERIAL AND METHODS: This prospective study included 34 patients (15 women and 19 men) aged 59 (18) years with clinical symptoms of spondylodiskitis. Whole-body PET/CT and bone scan combined with planar and SPECT/CT Ga was performed in all patients. Diagnosis of spondylodiskitis was made by microbiology and/or on the basis of clinical and laboratory findings and imaging follow-up. RESULTS: Spondylodiskitis was confirmed in 18 of 34 patients. In the other 16 patients, spondylodiskitis was finally excluded, and the most frequent findings observed were degenerative spondyloarthropathy (n = 7), vertebral fracture (n = 3), endocarditis (n = 2), and other processes (n = 4). The sensitivity and specificity of combined bone scan and Ga were 78% and 81%, with a positive predictive value of 82%, a negative predictive value of 76%, and an overall accuracy of 79%. SPECT/CT with Ga helped identify soft tissue involvement in 10 of 18 patients. The sensitivity and specificity of PET/CT were 89% and 88%, with a positive predictive value of 89%, a negative predictive value of 87%, and an overall accuracy of 88%. Concordance between Ga and PET/CT was good (κ = 0.71; 95% confidence interval, 0.48-0.94). PET/CT was able to detect soft tissue involvement in 12 of 18 patients. In 2 patients, a multifocality was found, which was only diagnosed by PET/CT. CONCLUSIONS: PET/CT is useful in the diagnosis of spondylodiskitis, with more accurate results than combined bone scan and Ga. SPECT/CT with Ga is recommended, especially when planar bone scan and Ga pattern is suggestive of spondylodiskitis.