The Role of ¹⁸F-FDG PET/CT in the Diagnosis of Infectious and Inflammatory Diseases.

ABSTRACT: ¹⁸F-FDG PET/CT has established itself as a sensitive whole-body imaging modality used in the diagnosis of infectious and inflammatory diseases. The technique provides critical diagnostic information in complex or atypical clinical presentations. For fever of unknown origin and systemic infections, ¹⁸F-FDG PET/CT can yield clinically relevant information in approximately 50-79% of cases, even after inconclusive conventional diagnostic workup, and the diagnostic scan enables targeted therapeutic decisions. In the diagnosis of prosthetic and implant-related infections, including pacemaker, LVAD, and vascular graft infections, ¹⁸F-FDG PET/CT represents a valuable adjunct to CT and MRI; meta-analyses report sensitivity and specificity of approximately 86% for periprosthetic infections. In prosthetic valve endocarditis, it substantially improves diagnostic confidence compared to echocardiography, which is limited in the setting of prosthetic valves; the technique is recommended as an adjunct modality in the ESC endocarditis guidelines (2023), and it achieves sensitivity and specificity of 80-87%. In native valve endocarditis, ¹⁸F-FDG PET/CT demonstrates lower sensitivity. In spondylodiscitis and osteomyelitis, meta-analytic data report sensitivities and specificities of approximately 95% and 88-91%, respectively; observational data suggest an association with lower in-hospital mortality rates, without implying a causal relationship.These findings have substantially contributed to the revision of international guidelines and procedural standards. The joint guidelines of the EANM and SNMMI (2024/2025) confirm the evidence base and provide practice-oriented recommendations regarding indications, acquisition protocols, and interpretation of ¹⁸F-FDG PET/CT in infectious and inflammatory imaging.

KEY POINTS: · High sensitivity of ¹⁸F-FDG PET/CT for infection focus detection after inconclusive prior workup. · Particularly valuable in fever of unknown origin, sepsis, and implant-associated infections. · Superior performance in prosthetic valve endocarditis and detection of extracardiac complications. · Supported by standardized EANM/SNMMI protocols (2024/2025).

KEY POINTS: · Wachenfeld E, Weiß J, Schwarzenböck S et al. The Role of ¹⁸F-FDG PET/CT in the Diagnosis of Infectious and Inflammatory Diseases. Rofo 2026; DOI 10.1055/a-2913-6380.