18F-FDG PET/CT in sarcoidosis management: review and report of 20 cases

To evaluate the interest of 18F-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) for diagnosis and therapeutic follow-up of patients with sarcoidosis. Twenty consecutive patients with biopsy-proven sarcoidosis were retrospectively included, in particular, 13 and seven cases of thoracic and extra-thoracic sarcoidosis, respectively. All patients underwent 18F-FDG PET/CT, and 12 of them also 67Ga scintigraphy. Five patients were re-examined by 18F-FDG PET/CT to assess response to corticosteroid (CS) treatment. Sensitivity of 18F-FDG PET/CT in detecting active sarcoidosis localizations was determined considering only biopsy-proven sites. For thoracic, sinonasal, and pharyngo-laryngeal localizations, 18F-FDG PET/CT sensitivity was 100%, 100%, and 80%, respectively. Overall sensitivity for all 36 biopsy-proven localizations improved from 78% to 87% after excluding skin involvement. Considering only the 12 patients who underwent both scintigraphic examinations, overall sensitivity of 67Ga scintigraphy and 18F-FDG PET/CT was 58% and 79%, respectively and improved to 67% and 86% after excluding all sites of skin involvement. To evaluate the efficacy of CS treatment, five enrolled patients underwent second 18F-FDG PET/CT. Complete regression of all foci of pathological tracer uptake was showed in two cases, permitting CS withdrawal after 2 and 6 months. Improvement but incomplete regression of mediastino-pulmonary disease occurred in two patients treated with CS for 19 and 21 months. Disease progression was assessed in one patient treated with decreasing doses of CS during 16 months. 18F-FDG PET/CT allows to obtain a complete morpho-functional cartography of inflammatory active localizations and to follow treatment efficacy in patients with sarcoidosis, particularly in atypical, complex, and multisystemic forms. (orig.)