PMC4440418_01
Statistical parametric map of cerebrovascular reactivity (CVR) for a patient with mTBI at the initial scan two months post mTBI (upper panel) and the follow scan one year later (lower panel). Upper panel: Negative CVR indicated by cool colors was observed in both gray and white matter in the frontal and parietal areas, more on the left hemisphere, in the initial scan of the mTBI patient. MRI signal time series were extracted from the selected regions of interest in the left dorsolateral frontal area (blue circle) and in the right dorsolateral frontal area (red circle). The shaded columns in the time series plots indicate breath-hold epochs. The time series from the left medial parietal area was not in synchronous with the breath-hold epochs. Lower panel: Positive CVR indicated by warm colors was observed in the left parietal areas in the follow-up scan of the mTBI patient. The MRI signal time series from the tissues in left (blue circle) and right (red circle) dorsolateral frontal areas were in synchronous with the breath-hold epochs. a.u., arbitrary units.
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F1
The initial breath-hold fMRI scan at two months post concussion demonstrated hemispheric asymmetry of CVR extending from the frontal gray matter to parietal white matter (Figure 1).
Statistical parametric maps of cerebrovascular reactivity (CVR) for five healthy subjects (HC1-HC5). Positive CVR indicated by warm colors was observed in most of the brain regions. The MRI signal time series from the tissues in left (blue circle) and right (red circle) dorsolateral frontal areas of the healthy controls follow closely the breath-hold epochs. The shaded columns in the time series plots indicate breath-hold epochs. a.u., arbitrary units.
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F2
In contrast, the MRI signal response time series of healthy control subjects in both gray and white matter followed closely the referenced hypercapnic stimulus time epochs in breath-hold challenges (Figure 2).