The efficacy of brain ¹⁸F-fluorodeoxyglucose positron emission tomography in neuropsychiatric lupus patients with normal brain magnetic resonance imaging findings

Brain involvement in systemic lupus erythematosus (SLE) is a significant source of morbidity and mortality. Therefore, the early detection and treatment of brain involvement in SLE is of utmost importance; however, a confirmative diagnostic tool for neuropsychiatric SLE is yet to be developed. In this study, we investigated the efficacy of ¹⁸F-FDG-PET for detection of brain involvement in patients with SLE with normal magnetic resonance imaging (MRI) findings. Twenty patients with SLE, who presented with neuropsychiatric symptoms despite normal brain MRI findings and who underwent brain ¹⁸F-FDG- PET, were enrolled. The most common neuropsychiatric manifestation was headache (45%), followed by seizure (20%) and mood disorder (20%). ¹⁸F-FDG-PET revealed significant glucose metabolic abnormalities in 15 of 20 patients (75%). The temporal (55%) and the occipital (55%) lobes were the most susceptible brain regions, followed by the frontal lobe (50%). However, neuropsychiatric symptoms were not geographically correlated to ¹⁸F-FDG-PET findings. Two patients with abnormal ¹⁸F-FDG- PET findings underwent follow-up brain ¹⁸F-FDG-PET after remission, which showed complete resolution of abnormal glucose metabolism. Our data suggest that ¹⁸F-FDG-PET may be an additional diagnostic modality complementary to MRI, when MRI is unable to provide evidence of brain involvement in patients with SLE.