Physiologic underpinnings of negative BOLD cerebrovascular reactivity in brain ventricles

摘要: Abstract With a growing need for specific biomarkers in vascular diseases, there has been surging interest mapping cerebrovascular reactivity (CVR) of the brain. This index can be measured by conducting hypercapnia challenge while acquiring blood-oxygenation-level-dependent (BOLD) signals. A BOLD signal increase with is expected outcome and represents majority literature reports; this work we report an intriguing observation apparently negative CVR response at 3 T, during inhalation 5% CO 2 balance medical air. These “negative-CVR” clusters were specifically located ventricular regions brain, where CSF abundant results intense baseline signal. The amplitude was − 0.51 ± 0.44% (N = 14, age 26 ± 4 years). We hypothesized that might not due to decrease oxygenation but rather volume effect which bright replaced less intensive blood as result vasodilation. To test this, performed inversion-recovery (IR) experiment suppress (N = 10, 27 ± 5 years). maneuver imaging sequence reversed sign (to 0.66 ± 0.25%), suggesting change predominant reason experiment. Further support hypothesis provided hyperoxia experiment, no voxels showed response, presumably because vasodilation usually associated challenge. Absolute CBF new group subjects (N = 8, 29 ± 7 years) it found increased 48% upon inhalation, most likely than decreased. findings from study suggest dilation vessels accompanied shrinkage space, responsible brain ventricles.