Examining the resting-state vascular connectivity using fMRA in comparison with fMRI: a preliminary study

Abstract

This study examined resting-state functional connectivity in the vascular system of the brain using functional magnetic resonance angiography (fMRA) with an ultra-high-field 7T MRI. Four healthy individuals participated in the functional imaging study using fMRA and functional MRI (fMRI) for determination of vascular and blood oxygenation level-dependent (BOLD) connectivity, respectively. We calculated voxel-wise connectivity maps and measured the correlation coefficients of the region of interest (ROI)-wise connectivity in the resting-state human brain. Z-map in the posterior cingulate cortex showed more correlated voxels in fMRA than fMRI. There was little or weak interhemispheric vascular connectivity using fMRA in the lateral parietal cortex and the lateral temporal cortex. In contrast, both vascular and BOLD interhemispheric correlations in the precentral gyrus were strong. Correlation coefficients for ROI-wise connectivity analysis were statistically different between fMRA and fMRI in the left and right lateral parietal cortex and lateral temporal cortex (P=0.029). Unlike BOLD connectivity, vascular connectivity showed little interhemispheric correlation in the default mode network. These results could provide the vascular connectivity on the basis of arterial response that can only be obtained by fMRA with an ultra-high-field environment along with further studies. Therefore, this method could provide additional and supplementary information for investigating the vascular effect in patients with cerebrovascular disease. Copyright (C) 2015 Wolters Kluwer Health, Inc. All rights reserved.