Figure 1.

The GABA receptor availability in stroke patients seen with [¹⁸F]FMZ PET.

Receptor availability on [¹⁸F]FMZ PET was calculated as the regional uptake ratio, in which the regional uptake is relative to the activity of the pons, where receptor sites are negligible. Then, significant differences in receptor availability in the 1- and 3-month PET were compared with those of age-matched healthy controls using general linear models in a voxel-based manner. (A) The GABA receptor availability in stroke patients was increased in the ipsilesional cortical area (supramarginal cortex, BA 40) and contralateral cerebellum in comparison with age-matched healthy controls at 1 month after stroke. (B) The findings were similar at 3 months after stroke, with a more widespread reduction in GABA receptors in the cortical and subcortical white matter in the contralateral cerebellum. The greater receptor availability in the contralateral cerebellum persisted, but to a lesser extent, and the higher perilesional receptor availability was no longer significant. (C) A comparison of the PET study between 1 month and 3 months after stroke (Δ=3 month−1 month) revealed that the GABA receptor availability generally decreased throughout the cerebral cortex and cerebellum during the functional recovery period, especially in the contralateral hemisphere. The mean uptake ratio of FMZ PET in the brain was also decreased significantly at 3 months as compared to at 1 month after stroke (Kim et al., 2014). This figure has been reproduced with per-mission. GABA: γ-Aminobutyric acid; [¹⁸F]FMZ PET: [¹⁸F]flumazenil positron emission tomography.