Abstracts

Rationale: Glucose transporter 1 deficiency syndrome (GLUT1-DS) is caused by impaired glucose uptake at the blood?"brain barrier. It is diagnosed by low glucose level in CSF, impaired glucose uptake into erythrocytes, and SLC2A1 gene mutation. Although Neuroimaging findings are considered nonspecific, it has been reported that FDG-PET shows low uptake in thalami and cerebral cortex and relatively high uptake in basal ganglia. We performed FDG-PET study in patients with GLUT1-DS to reveal if the FDG-PET findings are helpful in the diagnosis of GLUT1-DS. Methods: We performed FDG-PET in 7 patients (mean age 10 years, range 2 to 21 years) with GLUT1-DS. PET was compared with those of 30 controls (mean age 10 years, range 2 to 21 years) by statistical parametric mapping (SPM8, Welcome Neurological Institute). The controls had epilepsy of unknown etiology, and MRI and PET were normal on visual inspection. We also measured ratio of mean radioactivity in lenticular nuclei and thalami in each patient and control by using regions of interest generated from WFU PickAtlas. We determined sensitivity and specificity of the ratio for the differential diagnosis of GLUT1-DS and controls. Results: By visual inspection, PET revealed focal cortical hypometabolism in 3 patients, diffuse cortical hypometabolism in 1, bilateral thalamic hypometabolism in 3, and hypermetabolism in bilateral basal ganglia in 4. SPM showed significantly decreased uptake in bilateral thalami and increased uptake in bilateral basal ganglia in patients with GLUT1-DS. The mean of the lenticular nuclei/thalami ratio was 1.60 0.23 in patients and 1.25 0.10 in controls. By setting cut-off value of the lenticular nucleus/thalami ratio to 1.4, patients with Glut1-DS were differentiated from controls with sensitivity 0.85 and specificity 0.93. Conclusions: It is useful to evaluate the lenticular nuclei/thalami ratio on FDG-PET for the diagnosis of GLUT1-DS in patients with epilepsy and unknown etiology. The unique pattern of glucose metabolism on PET is supposed to be caused by expression of glucose transporters and local glucose metabolism in human brain from fetal period, and abnormal thalamo-cortical networks. Funding: None