Systematic Review of [18F]FDG-PET/CT Imaging in Pulmonary Sarcoidosis

Overview

This systematic review evaluates the diagnostic performance and prognostic value of [18F]FDG-PET/CT imaging in pulmonary sarcoidosis. It highlights the role of FDG-PET/CT in detecting active inflammation and correlating metabolic activity with clinical markers of lung function and treatment response.

Background

Sarcoidosis is a multisystem inflammatory disease characterized by non-necrotising granulomas, commonly affecting the lungs and mediastinal lymph nodes. Diagnosis is challenging due to variable clinical presentations and often inconclusive conventional markers. CT imaging is standard but may require histological confirmation. FDG-PET/CT has emerged as a sensitive tool for detecting inflammatory activity, with an established role in cardiac sarcoidosis, but its utility in pulmonary sarcoidosis remains to be fully defined.

Data Highlights

The review included studies assessing histologically or clinically confirmed pulmonary sarcoidosis patients undergoing FDG-PET/CT imaging. Diagnostic accuracy data such as sensitivity, specificity, true/false positive and negative rates were extracted. Prognostic studies correlated SUVmax values with lung function parameters (FVC, DLCO) and treatment outcomes. Risk of bias was assessed using QUADAS-2, ensuring quality and reliability of included studies.

Key Findings

• FDG-PET/CT demonstrates high sensitivity in detecting active pulmonary sarcoidosis inflammation, sometimes preceding morphological changes on CT.
• Metabolic activity measured by SUVmax correlates with clinical markers of lung function, such as forced vital capacity (FVC) and diffusing capacity for carbon monoxide (DLCO).
• FDG-PET/CT can aid in identifying subclinical disease activity, potentially guiding timely therapeutic interventions.
• Serial FDG-PET/CT imaging shows promise in monitoring treatment response and disease progression in pulmonary sarcoidosis.
• There is variability in study methodologies and patient populations, highlighting the need for standardized protocols in future research.

Clinical Implications

FDG-PET/CT imaging offers a valuable adjunct to conventional diagnostic methods by detecting active inflammation in pulmonary sarcoidosis, which may not be apparent on CT alone. Incorporating FDG-PET/CT can improve disease staging, guide biopsy sites, and monitor treatment efficacy, ultimately aiding personalized patient management.

Conclusion

FDG-PET/CT is a sensitive imaging modality for assessing pulmonary sarcoidosis activity and correlates with functional lung impairment. Further standardized studies are warranted to optimize its clinical application in diagnosis and management.

References

1. ATS/ERS/WASOG 2023 -- Diagnostic Criteria for Sarcoidosis
2. QUADAS-2 Tool 2011 -- Quality Assessment of Diagnostic Accuracy Studies
3. RobVis Software 2020 -- Risk of Bias Visualization