18F‐FDG PET/CT Reveals Characteristic Prefrontal‐Posterior Cingulate Hypometabolism in anti‐AMPAR Encephalitis to Understand Cerebral Function: Insights From an Eight‐Patient Cohort

• Published in: CNS neuroscience & therapeutics Vol. 31; no. 10
• Main Authors: Cong, Hengri, yuan, Leilei, Zheng, Pei, Xu, Xuan, Dong, Wenyue, Tian, DeCai, Yin, Linlin, Ma, Yueta, Song, Tian, Zhao, Yanxue, Xu, Yun, Zhang, Mengting, Liu, Baitao, Chang, Guoqiang, Sun, Ke, Ma, Wenping, Ai, Lin, Xu, Wangshu
• Format: Journal Article
• Language: English
• Published: Oxford John Wiley & Sons, Inc 01.10.2025
• Subjects: 18F‐FDG PET/CT; Acids; Antibodies; Antigens; anti‐AMPAR encephalitis; Autoantibodies; Autoimmune diseases; Basal ganglia; Blood flow; cerebral function; Cerebrospinal fluid; Cognitive ability; Coronaviruses; COVID-19; Electroencephalography; Encephalitis; Glioma; Hemodynamics; Hepatocellular carcinoma; Hospitals; Immunoglobulins; Intensive care; Liver cancer; Lung carcinoma; Magnetic resonance imaging; Malignancy; metabolic patterns; Metabolism; Patients; Proteins; Standard scores; Temporal lobe; Thymoma; Tomography; Work stations; α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors
• ISSN: 1755-5930; 1755-5949; 1755-5949
• DOI: 10.1111/cns.70633

ABSTRACT Purpose Anti‐AMPAR encephalitis is a rare antibody‐mediated disorder, and its clinicoradiological profile is incompletely defined. We aimed to characterize the clinical presentation and cerebral metabolic patterns of Chinese adults with anti‐AMPAR encephalitis using 18F‐FDG PET/CT. Methods From August 2016 to August 2022, we retrospectively identified patients from two neurology centers who were positive for anti‐AMPAR antibodies in serum and/or cerebrospinal fluid. Demographic data, presenting symptoms, MRI and 18F‐FDG PET/CT findings (Discovery Elite, GE Healthcare), treatment regimens, and outcomes were extracted and analyzed. Results Eight patients (four women) were included; median age was 53 years (range 37–63). Anti‐AMPA2R antibodies were detected in seven cases and anti‐AMPA1R antibodies in one. Limbic manifestations dominated, particularly cognitive decline and abnormal behavior; severe disease necessitated intensive care support in one patient, who nonetheless achieved a good outcome. Malignancy was documented in three individuals (lung carcinoma, hepatocellular carcinoma, and thymoma), and three harbored additional neural autoantibodies. MRI was abnormal in five patients (62.5%). All five subjects who underwent 18F‐FDG PET/CT displayed prefrontal hypometabolism; three also showed posterior cingulate hypometabolism. Focal hypermetabolism was observed in the right temporal lobe (one case) and in the left thalamus (one case). Conclusion Anti‐AMPAR encephalitis usually presents as limbic encephalitis and is marked by prefrontal and posterior cingulate hypometabolism on 18F‐FDG PET/CT. In some instances, hypermetabolism was observed in the basal ganglia or temporal lobes, possibly reflecting the local blood flow. Anti‐AMPAR encephalitis is an extremely rare form of antibody‐mediated encephalitis. Understanding the brain tissue hemodynamics is crucial for assessing the disease progression and guiding treatment. The metabolic status of brain tissue can serve as an objective indicator of the hemodynamics in extracranial blood vessels via 18F‐FDG PET/CT imaging.