Functional imaging in extrapulmonary sarcoidosis: FDG-PET/CT and MR features

Area of Science:

• Radiology
• Nuclear Medicine
• Immunology

Background:

• Sarcoidosis is a multisystem granulomatous disease with frequent extrapulmonary involvement (30-50% of patients).
• Accurate diagnosis and characterization of extrapulmonary sarcoidosis are essential for effective management.

Purpose of the Study:

• To review the utility of F-FDG PET/CT and MR imaging in diagnosing and managing extrapulmonary sarcoidosis.
• To highlight characteristic imaging patterns for various organ involvements.

Main Methods:

• Review of current literature on FDG-PET/CT and MR imaging in extrapulmonary sarcoidosis.
• Description of specific imaging findings in cardiac, central nervous system, bone marrow, muscular, and nodal sarcoidosis.

Main Results:

• FDG-PET/CT and MR enhance diagnostic accuracy, differentiate active inflammation from fibrosis, and guide biopsies and therapy.
• Characteristic imaging signs include T2 hypointensity in CNS sarcoidosis, "dark star" and "tiger man" signs in muscular sarcoidosis.
• FDG-PET/CT effectively detects lymphadenopathy, though differentiation from other pathologies can be challenging.

Conclusions:

• FDG-PET/CT and MR imaging are invaluable tools for diagnosing and managing extrapulmonary sarcoidosis.
• Familiarity with specific imaging patterns improves lesion characterization and patient care.