FDG-PET in patients with autoimmune encephalitis: a review of findings and new perspectives

PurposeThe present review aims to discuss the role of the brain F-18-FDG-PET and F-18-FDG-PET/CT (FDG-PET) in diagnosis and follow-up of the autoimmune encephalitis (AE) patients, highlighting the main findings and the new perspectives on use of these methods in the study of the disease.MethodsThe literature search was performed in the following databases: PubMed/MEDLINE, Scopus, Web of Science, Embase, and Google Scholar, according to the PRISMA statement. The main terms of search were: autoimmune encephalitis AND F-18-FDG-PET OR F-18-FDG-PET/CT, or the combination between the term F-18-FDG-PET OR F-18-FDG-PET/CT AND the antibodies receptors abbreviations (e.g., NMDA, VGKC, etc.). The methodological quality of the publications was assessed according to the QUADAS-2 criteria.ResultsThe search of the articles found 56 main articles. These articles encompassed 1,462 patients with AE positive antibodies, from which 808 had brain FDG-PET images with 714 (88.67%) showing alterations. Furthermore, some AE antibodies have specific metabolic signatures, detected in the images, which are discussed in the text. Moreover, patients at different stages of the disease may present different brain metabolic patterns. The areas of more common hypermetabolism were basal ganglia, hippocampus, amygdala, and cerebellum. The areas of more common hypometabolism were the visual cortex and a diffuse cortical metabolism.ConclusionsThis extensive literature review shows the high sensitivity of FDG-PET and FDG-PET/CT in patients with AE. FDG-PET detects findings of hyper and hypometabolism which are suggestive of AE. Besides, AE caused by the different antibodies may present specific alterations which may be suggestive of each one. However, more prospective studies are necessary for these images become a standard diagnostic method of AE.

Automated summary

The role of brain F-18-FDG-PET and F-18-FDG-PET/CT in the diagnosis and follow-up of autoimmune encephalitis (AE) patients is discussed in this review. The review highlights the main findings and new perspectives on the use of these methods in studying the disease. The sensitivity of FDG-PET and FDG-PET/CT in detecting hyper and hypometabolism in AE patients is shown in the literature. It is suggested that specific metabolic alterations detected in imaging may be suggestive of the different antibodies causing AE. However, more prospective studies are needed for these imaging techniques to become a standard diagnostic method for AE.