Nuclear Imaging in Sarcoidosis

Sarcoidosis is a multisystem granulomatosis which may result in a wide variety of clinical and biological presentations. Symptoms are often nonspecific, and incidental abnormal findings on chest radiography is rather common. Although sarcoidosis resolves favorably in most cases, some localizations can provoke functional impairment or even impact on patients' prognosis. The diagnosis is based on a pathological hallmark which is the non-necrotizing epithelioid-cell rich granuloma. Owing to the ability to detect inflammation throughout the body with a high sensibility, FDG-PET/CT gained a central role in sarcoidosis because it can suggest the diagnosis in certain clinical context, guide biopsy, evaluate the extent of the disease, help assess the prognosis, and monitor immunosuppressive therapy. This review will briefly describe clinical and typical findings of conventional imaging according to organ involvement, in order to highlight the additional information provided by nuclear imaging. In the future, we can expect to further improve diagnostic performance of imaging in some indications through the availability of more specific radiopharmaceuticals and the wider use of combined PET/MRI.