Abnormal brain metabolism on FDG-PET/CT is a common early finding in autoimmune encephalitis. Issue 4 (July 2017)

• Record Type: Journal Article
• Authors: Probasco, John C.; Solnes, Lilja; Nalluri, Abhinav; Cohen, Jesse; Jones, Krystyna M.; Zan, Elcin; Javadi, Mehrbod S.; Venkatesan, Arun
• Is Part Of: Neurology. Volume 4:Issue 4(2017)
• Publication Date: 2017-07
• Subjects: Neuroimmunology -- Periodicals; Neurology -- Periodicals; 616.8
• DOI: 10.1212/NXI.0000000000000352
• Languages: English
• ISSNs: 2332-7812

Abstract

Abstract : Objective: To compare the rate of abnormal brain metabolism by FDG-PET/CT to other paraclinical findings and to describe brain metabolism patterns in autoimmune encephalitis (AE). Methods: A retrospective review of clinical data and initial dedicated brain FDG-PET/CT studies for neurology inpatients with AE, per consensus criteria, treated at a single tertiary center over 123 months. Z-score maps of FDG-PET/CT were made using 3-dimensional stereotactic surface projections with comparison to age group–matched controls. Brain region mean Z-scores with magnitudes ≥2.00 were interpreted as significant. Comparisons were made to rates of abnormal initial brain MRI, abnormal initial EEG, and presence of intrathecal inflammation. Results: Sixty-one patients with AE (32 seropositive) underwent brain FDG-PET/CT at median 4 weeks of symptoms (interquartile range [IQR] 9 weeks) and median 4 days from MRI (IQR 8.5 days). FDG-PET/CT was abnormal in 52 (85%) patients, with 42 (69%) demonstrating only hypometabolism. Isolated hypermetabolism was demonstrated in 2 (3%) patients. Both hypermetabolic and hypometabolic brain regions were noted in 8 (13%) patients. Nine (15%) patients had normal FDG-PET/CT studies. CSF inflammation was evident in 34/55 (62%) patients, whereas initial EEG (17/56, 30%) and MRI (23/57, 40%) were abnormal in fewer. Detection of 2 or more of these paraclinical findings was in weak agreement with abnormal brain FDG-PET/CT (κ = 0.16, p = 0.02). Conclusions: FDG-PET/CT was more often abnormal than initial EEG, MRI, and CSF studies in neurology inpatients with AE, with brain region hypometabolism the most frequently observed.