The voxel-wise analysis of false negative fMRI activation in regions of provoked impaired cerebrovascular reactivity
Fig 2
Schematic overview of the analysis pipeline.
1) Representation of the raw BOLD-fMRI data obtained from the MRI system. 2) From the raw BOLD-fMRI images t-value maps are then calculatedusing a mass-univariate general linear model within SPM12. 3) By using a predetermined t-value threshold of 3.43, all significant voxels of each t-value map are combined into a significant-t-value binary mask, i.e. a combined T-map. 4)This map is then overlaid onto the predefined ROIsto determine the significant t-values within each ROI. 5)The BOLD-CVR and fMRI Δ%signal maps for the normocapnic condition are calculated and the values of the combined significant t-value voxels for each region of interest are scatter-plotted. 6)The BOLD-CVR and fMRI Δ%signal maps for the hypercapnic condition are calculated and the values of the combined significant t-value voxels for each region of interest are scatter-plotted. Abbreviations: Blood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR, defined as %signal change/mmHg CO2 change). Functional MRI (fMRI, defined as %signal change).