title: Diagnostic Value of18F-FDG PET/CT Versus MRI in the Setting of Antibody-Specific Autoimmune Encephalitis.
abstract: Diagnosis of autoimmune encephalitis presents some challenges in the clinical setting because of varied clinical presentations and delay in obtaining antibody panel results. We examined the role of neuroimaging in the setting of autoimmune encephalitides, comparing the utility of18F-FDG PET/CT versus conventional brain imaging with MRI.Methods:A retrospective study was performed assessing the positivity rate of MRI versus18F-FDG PET/CT during the initial workup of 23 patients proven to have antibody-positive autoimmune encephalitis.18F-FDG PET/CT studies were analyzed both qualitatively and semiquantitatively. Areas of cortical lobar hypo (hyper)-metabolism in the cerebrum that were 2 SDx from the mean were recorded as abnormal.Results:On visual inspection, all patients were identified as having an abnormal pattern of18F-FDG uptake. In semiquantitative analysis, at least 1 region of interest with metabolic change was identified in 22 of 23 (95.6%) patients using a discriminatingzscore of 2. Overall,18F-FDG PET/CT was more often abnormal during the diagnostic period than MRI (10/23, 43% of patients). The predominant finding on brain18F-FDG PET/CT imaging was lobar hypometabolism, being observed in 21 of 23 (91.3%) patients. Hypometabolism was most commonly observed in the parietal lobe followed by the occipital lobe. An entire subset of antibody-positive patients, anti-N-methyl-d-aspartate receptor (5 patients), had normal MRI results and abnormal18F-FDG PET/CT findings whereas the other subsets demonstrated a greater heterogeneity.Conclusion:Brain18F-FDG PET/CT may play a significant role in the initial evaluation of patients with clinically suspected antibody-mediated autoimmune encephalitis. Given that it is more often abnormal when compared with MRI in the acute setting, this molecular imaging technique may be better positioned as an early biomarker of disease so that treatment may be initiated earlier, resulting in improved patient outcomes.
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Lilja B
authors.initials: LB
authors.lastname: Solnes
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Krystyna M
authors.initials: KM
authors.lastname: Jones
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Rowe
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Puskar
authors.initials: P
authors.lastname: Pattanayak
authors.affiliation: The Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Abhinav
authors.initials: A
authors.lastname: Nalluri
authors.affiliation: The Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Arun
authors.initials: A
authors.lastname: Venkatesan
authors.affiliation: The Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: John C
authors.initials: JC
authors.lastname: Probasco
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Mehrbod S
authors.initials: MS
authors.lastname: Javadi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D004660:Encephalitis / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D050031:Hashimoto Disease / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG PET/CT; MRI; altered mental status; antibody specific encephalitis; autoimmune encephalitis