Abstract
2014
Objectives: 1)Discuss the role of FDG-PET in sarcoidosis 2)Identify the position of FDG-PET/CT in the cascade of management of sarcoidosis. Methods: The utility of FDG-PET in diagnosis and management of variable inflammatory disorders has been long established owing to their high uptake of FDG, due to their high glycolysis rate and thus appearing as hot spots on FDG-PET imaging. Besides the superior sensitivity of PET to target inflammatory activity on a molecular level before morphological changes can be observed by conventional imaging techniques as CT or MRI. However, the crown jewel of FDG-PET in the recent years have been its unique ability for quantitative assessment of the global disease burden, through through implementation of Region of interest Visualization, Evaluation, and Image Registration (ROVER) method (ABX GmbH, Germany). It enablescalculation of total lesion glycolysis (TLG) and metabolic tumor volume (MTV), that are used to determine global disease burden. Numerous studies have investigated and established the role of FDG-PET in multiple inflammatory disorders as fever of unknown origin (FUO), vasculitis, atherosclerosis and sarcoidosis.
Results: Studies and scientific analysis have shown the great role of hybrid PET/CT systems utilizing the radiotracer FDG. By incorporating the functional imaging of PET that assesses the metabolic activity of different tissues with the anatomical localization capabilities of CT. Sarcoidosis is a multisystem disease characterized by formation of non-caseating granulomas, with the lung and intrathoracic lymph nodes being the classic sites of affection, although, it can affect any site as cardiac, head and neck, or musculoskeletal systems. FDG PET/CT has shown great utility in the diagnosis, staging and diagnosis of cardiac sarcoidosis, and with the implementation of quantitative assessment rather than the classical visualized assessment of the FDG uptake, global disease burden is estimated and provides vital information regarding all manifestations of sarcoidosis including pulmonary, extra-pulmonary manifestations of sarcoidosis as cardiac, and lymph node involvement. Conclusion: FDG-PET/CT shows great promise as a diagnostic tool for sarcoidosis as it presents vital information regarding staging, re-staging and monitoring therapy response in cardiac sarcoidosis as well as classic presentation as pulmonary and intrathoracic lymph node involvement, and extra-pulmonary manifestations of sarcoidosis, with crucial role of global assessment of the disease using quantitative techniques.