Iterative analysis of cerebrovascular reactivity dynamic response by temporal decomposition

Brain Behav. 2017 Jul 26;7(9):e00705. doi: 10.1002/brb3.705. eCollection 2017 Sep.

Abstract

Objective: To improve quantitative cerebrovascular reactivity (CVR) measurements and CO 2 arrival times, we present an iterative analysis capable of decomposing different temporal components of the dynamic carbon dioxide- Blood Oxygen-Level Dependent (CO 2-BOLD) relationship.

Experimental design: Decomposition of the dynamic parameters included a redefinition of the voxel-wise CO 2 arrival time, and a separation from the vascular response to a stepwise increase in CO 2 (Delay to signal Plateau - DTP) and a decrease in CO 2 (Delay to signal Baseline -DTB). Twenty-five (normal) datasets, obtained from BOLD MRI combined with a standardized pseudo-square wave CO 2 change, were co-registered to generate reference atlases for the aforementioned dynamic processes to score the voxel-by-voxel deviation probability from normal range. This analysis is further illustrated in two subjects with unilateral carotid artery occlusion using these reference atlases.

Principal observations: We have found that our redefined CO 2 arrival time resulted in the best data fit. Additionally, excluding both dynamic BOLD phases (DTP and DTB) resulted in a static CVR, that is maximal response, defined as CVR calculated only over a normocapnic and hypercapnic calibrated plateau.

Conclusion: Decomposition and novel iterative modeling of different temporal components of the dynamic CO 2-BOLD relationship improves quantitative CVR measurements.

Keywords: blood‐oxygen‐level‐dependent; carbon dioxide; cerebrovascular reactivity; functional magnetic resonance imaging; humans.

MeSH terms

  • Brain / blood supply*
  • Brain / diagnostic imaging
  • Cerebrovascular Circulation / physiology*
  • Humans
  • Hypercapnia / diagnostic imaging*
  • Magnetic Resonance Imaging / methods*
  • Oxygen / metabolism*

Substances

  • Oxygen