Changing Brain Metabolism Patterns in Patients With ANMDARE: Serial 18F-FDG PET/CT Findings

The aim of this study was to describe brain metabolic changing patterns demonstrated by serial brain FDG PET/CT scans and their relationship with the clinical course in patients with anti-N-methyl-d-aspartate receptor encephalitis (ANMDARE).

Eighteen serial PET scans of 8 patients with ANMDARE were reviewed. All the 18 PET scans were divided into 4 groups according to studies timing in different clinical course: group A, the acute and subacute phase; group B, early recovery phase; group C, recovery phase; and group D, relapsing phase. Antibody levels of ANMDARE of all these patients were tested at the same time. The PET images of each group were analyzed visually and also compared with 10 age- and sex-matched normal controls using voxel-wise statistical parametric mapping analysis (SPM5).

Variable brain metabolic patterns and its association with the clinical course and the levels of NMDA antibody were demonstrated by FDG PET images. First, severe hypometabolism in bilateral occipital lobes and relatively mild hypermetabolism in the partial frontal and basal ganglia in acute and subacute phase, the level of antibody was high. Second, in early recovery phase when the symptoms was partially improved, extensive cortical hypometabolism was observed, and the level of antibody was low. Third, the patients in the recovery phase have no obvious neurological and psychiatric symptoms; PET images were nearly normal, and the antibodies tests were all negative, correspondingly. Fourth, 3 scans of relapsing phase presented heterogeneous brain metabolic abnormalities.

There existed a specific serial brain metabolic changing pattern that correlated with the clinical course and antibody level in ANMDARE.