Analysis of 18F-FDG PET metabolic characteristics in anti-glutamate decarboxylase 65 antibody-associated encephalitis based on cluster analysis
SUN Yue-qian
WANG Ning
GE Shi-hao
WANG Qun
Abstract：Objective To investigate the metabolic patterns of anti-glutamate decarboxylase 65(GAD65)antibody-associated encephalitis using 18F-FDG PET,and to analyze the correlations between these patterns and clinical or neuroimaging features.Methods A total of 25 patients with anti-GAD65 antibody-associated encephalitis admitted to Beijing Tiantan Hospital,Capital Medical University,from January 2018 to July 2024 were enrolled.All patients underwent 18F-FDG PET imaging.The whole brain of each patient was segmented into 116 brain regions,and cerebellum-normalized standard uptake value ratio(SUVRc)was calculated for each region.Principal component analysis(PCA)was used to reduce the dimensionality of SUVRc,and k-means clustering algorithm was applied to divide the patients into 2 clusters.Pearson and partial correlation analyses were performed to explore the correlations between metabolic activity of key brain regions and clinical indicators or MRI volumes.Results PCA showed that the top 5 brain regions contributing most to Principal Component 1 were all located in the occipital lobe,in order of left cuneus,right cuneus,right lingual gyrus,left inferior occipital gyrus and right inferior occipital gyrus.The k-means clustering algorithm divided the patients into 2 clusters(14 cases in Cluster 1,11 cases in Cluster 2).There were statistically significant differences in SUVRc of the left cuneus(F=7.946,P=0.000),right cuneus(F=8.406,P=0.000),right lingual gyrus(F=9.447,P=0.000),left inferior occipital gyrus(F=17.036,P=0.000),and right inferior occipital gyrus(F=18.312,P=0.000)between the 2 clusters and healthy controls.Further pairwise comparisons revealed that compared with the health controls,Cluster 2 had increased SUVRc in the left cuneus(t=3.809,P=0.000),right cuneus(t=2.959,P=0.000),right lingual gyrus(t=3.726,P=0.000),left inferior occipital gyrus(t=3.948,P=0.000),and right inferior occipital gyrus(t=3.846,P=0.000),so it was defined as the occipital lobe hypermetabolism cluster;Cluster 1 showed a decreasing trend in metabolic activity of these regions,thus defined as the non-occipital lobe hypermetabolism cluster.MRI volume analysis revealed that the brain regions with significant volume differences between the non-occipital lobe hypermetabolism cluster and occipital lobe hypermetabolism cluster were the cuneus(t=-2.214,P=0.038),superior occipital gyrus(t=-2.213,P=0.038),orbital gyrus(t=-2.829,P=0.010),lateral part of the superior temporal gyrus(t=-2.246,P=0.035),occipito-temporal medial sulcus(collateral sulcus),and lingual gyrus sulcus(t=-2.160,P=0.042).Conclusions Different metabolic patterns of anti-GAD65 antibody-associated encephalitis were identified by 18F-FDG PET combined with cluster analysis,and their associations with clinical and neuroimaging features were revealed,which deepens the understanding of the pathophysiological mechanisms of this disease.
Keywords：EncephalitisAutoimmune diseasesGlutamate decarboxylasePositron-emission tomographyCluster analysis
Publication Date：2025-12-25
Online Publishing Date：2026-01-23(First online date of this platform, not the publication date of the document)
Pages：8( 1113-1120 )