Abstract
1474
Objectives: To evaluate metabolic activity on brain F18 FDG PET CT in patients with Anti-LGI1 encephalitis.
Methods: In this retrospective study, 6 patients with confirmed diagnosis of Anti-LGI1 encephalitis who had total of 16 F18 FDG PET CT scans of the brain were included in the study. Quantitative analysis for PET imaging was done using NeuroQ™ version 3.75. NeuroQ™ provides regional assessment of human brain scans based on automated quantification of mean pixel values lying within standardized regions of interests (ROIs) and compares the brain regional activity to normal activity values of 50 normal controls. 47 areas in the brain were segmented and analyzed. Abnormal regions are determined based on having internally normalized ROI radiotracer uptake values falling more than 1.65 standard deviations below the mean value (in the Hypometabolic operation) and more than 1.65 standard deviations above the mean value (in the Hypermetabolic operation) for asymptomatic control group. Besides each individual scan results (Fig1) we also calculated the SD of average of the first scans of the 6 patients from the normal controls (Fig 2).
Results: The resultant SD of the averages of the first scans from normal controls showed that pons, midbrain, right anterior medial temporal cortex, left anterior medial temporal cortex and right posterior medial temporal cortex show hypermetabolic activity, while left primary visual cortex, right inferior frontal cortex, left inferior frontal cortex, left posterior cingulated cortex, right posterior cingulated cortex, left broca region, left anterior cingulated cortex, right anterior cingulated cortex, left mid frontal cortex, right mid frontal cortex, left medial frontal cortex and right medial frontal cortex showed significant hypometabolic activity (Fig 1). The significant hyper and hypometabolic areas for each scan are shown in Fig 2.
Conclusions: Anti-LGI1 encephalitis is a subtype of autoimmune encephalitis that results from antibodies targeted at leucine rich glioma inactivated 1 (LGI1) protein. This autoantigen is secreted from neuronal proteins and acts as a ligand for ADAM22 and ADAM23 which are epilepsy-related proteins (1). Early intervention improves long term outcomes (2). Patients may show cognitive abnormality and seizures (3). MRI results usually reveal medial temporal hyperintensity (4). Less is known regarding the F18 FDG PET evaluation of the patients. Herein, we present the results of 47 brain clusters based on FDG PET scans compared to 50 normal controls. Considering the abnormal signal in medial temporal areas on MRI, our results show that these areas are hypermetabolic. On the other hand frontal and cingulated areas show hypometabolic activity. These results provide better understanding of the nature of this neurologic disease and may help us diagnose patients at onset of disease which will allow us to intervene earlier.
In this issue
Jump to section
Related Articles
Cited By...
- No citing articles found.