The role of 18F-FDG PET/CT in spinal infections: A comprehensive diagnostic tool

Introduction: F-fluorodeoxyglucose positron emission tomography (FDG-PET) has emerged as complementary tool to MRI, enabling detection of metabolically active infectious processes. Research question: This study evaluates the diagnostic accuracy of FDG-PET/CT in patients with suspected spondylodiscitis and its ability to identify additional infectious foci. Material and methods: A retrospective analysis included 191 patients who underwent FDG-PET/CT for suspected spondylodiscitis between 01.01.2016 and 31.12.2023. PET findings were compared with MRI, pathological, and microbiological and clinical data. Results: Spinal infection was confirmed in 160 of 191 patients. In patients with inconclusive MRI findings (n = 46), FDG-PET/CT led to diagnostic reclassification in 21 cases (45.7%). In the subgroup analyzed for diagnostic accuracy (n = 56), sensitivity was 56% for FDG-PET/CT and 62% for MRI, increasing to 74% when both modalities were combined (p = 0.002). Specificity was 96% for FDG-PET/CT and 86% for MRI. FDG-PET/CT identified 23 previously unknown extraspinal infectious foci and confirmed 23 suspected foci, resulting in detection of infectious sources in 73% of patients. Infectious foci were detected more frequently in cervical infections (33.3% vs. 9.5%, p = 0.001). Patients undergoing FDG-PET/CT showed higher clinical resolution rates at follow-up (p = 0.045). Discussion and conclusion: FDG-PET/CT provides complementary value in suspected spondylodiscitis, particularly in cases with inconclusive MRI and for detecting additional infectious foci, supporting its role in multimodal diagnostic strategies.