Regional heterogeneity in the brain's response to hypoxia measured using BOLD MR imaging.

Blood oxygenation level-dependent (BOLD) magnetic resonance (MR) imaging is sensitive, in part, to the amount of paramagnetic deoxyhemoglobin in a voxel. This project was designed to determine whether there would be differences in the BOLD response between the hippocampus and other brain regions to acute hypoxia. R2* was quantified using a multi-echo gradient-echo sequence. The pyramidal CA1 region of the hippocampus showed a reduced response to changes in arterial oxygenation relative to cortex and basal ganglia and white matter. This difference may relate to the relative hypoxia sensitivity of the hippocampus. It also supports the premise that in functional MR imaging, the magnitude of the MR response to a stimulus may vary with the region of the brain.