Objective:

The purpose of this study was to compare the performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) versus contrasted CT in identifying viable biopsy targets to aid in the diagnosis of sarcoidosis in a rural neuroimmunology clinic serving both Vermont and upstate NY. 

Background:

Sarcoidosis is a multisystem inflammatory disease characterized by granulomatous inflammation. Diagnosis of neurologic involvement (neurosarcoidosis) is considered “definite”, “probable”, or “possible”, based on the presence of histopathologic confirmation within or outside the nervous system. Identification of systemic biopsy targets is therefore essential. Typically, structural imaging through CT with contrast is obtained first, and if a target is not identified, metabolic imaging through FDG-PET/CT is recommended. However, data directly comparing the relative yield of these modalities remain limited.

Design/Methods:

Patients with possible, probable, or definite neurosarcoidosis seen at a Vermont neuroimmunology clinic between 2016 and 2025 were identified by retrospective chart review. Of those with probable and definite neurosarcoidosis, the imaging modality (contrasted CT or FDG-PET/CT) that identified the systemic biopsy target leading to diagnosis was recorded. 

Results:

All 18 patients with probable neurosarcoidosis underwent contrasted CT, which identified lymphadenopathy or another viable biopsy target in 15/18 cases. FDG-PET/CT was performed in 11/18 cases and identified biopsy targets in 10/11 cases. In patients with probable neurosarcoidosis who underwent both studies, CT was positive in 7/11 (64%) and FDG-PET/CT was positive in 10/11 (91%). CT was negative and FDG-PET/CT was positive in 3/11 (27%), while CT was positive and FDG-PET/CT was negative in 1/11 (9%). 

Conclusions:

FDG-PET/CT demonstrated greater sensitivity than contrasted CT in identifying systemic biopsy targets in patients with suspected neurosarcoidosis. Neurologists should strongly consider follow up metabolic imaging in cases of suspected sarcoidosis when initial structural imaging is negative, as in our small cohort FDG-PET/CT led to definitive diagnosis in 27% of cases.