Assessment of Therapeutic Response in Pyogenic Vertebral Osteomyelitis Using F-FDG-PET/MRI.

Purpose: There is still no definite method to determine therapeutic response in pyogenic vertebral osteomyelitis (PVO). We analyzed the value of F-fluorodeoxyglucose positron emission tomography (FDG-PET) for assessing therapeutic response in PVO.

Methods: This retrospective study included 53 patients (32 men and 21 women) with lumbar PVO. The results of clinical assessments for therapeutic response were divided into "Cured" (group C) and "Non-cured" (group NC). The differences in clinical and radiological features of PVO lesions between the two groups were analyzed using clinical data and simultaneous FDG-PET/magnetic resonance imaging (MRI) obtained at each clinical assessment.

Results: Clinical assessments and FDG-PET/MRIs were performed at 41.89 ± 16.08 (21-91) days of parenteral antibiotic therapy. There were 39 patients in group C and 14 in group NC. Diagnostic accuracies (DAs) of FDG uptake intensity-based interpretation and C-reactive protein (CRP) for residual PVO were as follows ( < 0.01): 84.9% of the maximum standardized uptake value of PVO lesion (PvoSUV), 86.8% of ΔPvoSUV-NmlSUV (SUV of normal vertebra), 86.8% of ΔPvoSUV-NmlSUV (SUV of normal vertebra), and 71.7% of CRP. DAs were better (92.5-94.3%) when applying FDG uptake intensity-based interpretation and CRP together. Under the FDG uptake distribution-based interpretation, FDG uptake was significantly limited to intervertebral structures in group C ( = 0.026).

Conclusion: The interpretations of intensity and distribution of FDG uptake on FDG-PET are useful for detecting residual PVO in the assessment of therapeutic response of PVO. The combination of FDG-PET and CRP is expected to increase DA for detecting residual PVO.