Elsevier

NeuroImage: Clinical

Volume 12, February 2016, Pages 173-179
NeuroImage: Clinical

Hypercapnic evaluation of vascular reactivity in healthy aging and acute stroke via functional MRI

https://doi.org/10.1016/j.nicl.2016.06.016Get rights and content
Under a Creative Commons license
open access

Highlights

  • Breath-holding can be used to assess the validity of fMRI in stroke patients.

  • Vascular reactivity, estimated by breath-hold fMRI, was greatest in young controls.

  • Acute stroke patients and age-matched controls had similar vascular reactivity.

  • Modeling the breath-hold response on an individual basis can improve results.

Abstract

Functional MRI (fMRI) is well-established for the study of brain function in healthy populations, although its clinical application has proven more challenging. Specifically, cerebrovascular reactivity (CVR), which allows the assessment of the vascular response that serves as the basis for fMRI, has been shown to be reduced in healthy aging as well as in a range of diseases, including chronic stroke. However, the timing of when this occurs relative to the stroke event is unclear. We used a breath-hold fMRI task to evaluate CVR across gray matter in a group of acute stroke patients (< 10 days from stroke; N = 22) to address this question. These estimates were compared with those from both age-matched (N = 22) and younger (N = 22) healthy controls. As expected, young controls had the greatest mean CVR, as indicated by magnitude and extent of fMRI activation; however, stroke patients did not differ from age-matched controls. Moreover, the ipsilesional and contralesional hemispheres of stroke patients did not differ with respect to any of these measures. These findings suggest that fMRI remains a valid tool within the first few days of a stroke, particularly for group fMRI studies in which findings are compared with healthy subjects of similar age. However, given the relatively high variability in CVR observed in our stroke sample, caution is warranted when interpreting fMRI data from individual patients or a small cohort. We conclude that a breath-hold task can be a useful addition to functional imaging protocols for stroke patients.

Keywords

fMRI
Vascular reactivity
Stroke
Breath-hold
Neurovascular uncoupling

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