Utility of [18F]FDG PET/CT in sarcoidosis management: A retrospective case series.

Background: Sarcoidosis is a granulomatosis of variable manifestation and evolution. It is crucial to assess the disease's extent, activity, and severity to effectively manage and monitor patients with sarcoidosis. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG PET/CT) is a nuclear medicine technique that proved to be of great use in oncology. Its role in extra-oncological indications, including sarcoidosis, has been reported.

Methods: Twenty-five patients with sarcoidosis were retrospectively included. All patients underwent at least one [18F]FDG PET/CT scan. Five patients underwent a second [18F]FDG PET/CT to assess their response to corticosteroid treatment. Clinical data were gathered from medical records. Radiological and PET data were obtained from reports and digital imaging and communications in medicine (DICOM) archives.

Results: [18F]FDG PET/CT revealed active inflammation in 76% of patients. All had intrathoracic activity, including 76% mediastinal and 44% pulmonary lesions. Additionally, 60% of patients displayed associated extrathoracic activity, mainly in peripheral lymph nodes, spleen, and bone. Cardiac activity was reported in two patients. [18F]FDG PET/CT prompted a diagnostic biopsy in 32% of patients. [18F]FDG PET/CT had an impact on therapeutic decision-making in 60% of patients. Follow-up [18F]FDG PET/CT showed a complete metabolic response in two cases and an incomplete metabolic response in one patient. Disease progression was noted in two patients.

Conclusions: Providing a complete functional map of the extent of inflammatory active disease, [18F]FDG PET/CT proves to be particularly useful in the management of sarcoidosis patients, by explaining persistent disabling symptoms, revealing suitable sites for biopsy, guiding therapeutic decisions and assessing treatment response.