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Impact of baseline CO on Blood-Oxygenation-Level-Dependent MRI measurements of cerebrovascular reactivity and task-evoked signal activation


van Niftrik, Christiaan Hendrik Bas; Piccirelli, Marco; Bozinov, Oliver; Maldaner, Nicolai; Strittmatter, Catherine; Pangalu, Athina; Valavanis, Antonios; Regli, Luca; Fierstra, Jorn (2018). Impact of baseline CO on Blood-Oxygenation-Level-Dependent MRI measurements of cerebrovascular reactivity and task-evoked signal activation. Magnetic Resonance Imaging, 49:123-130.

Abstract

Neurovascular coupling describes the cascade between neuronal activity and subsequent Blood-Oxygenation-Level-Dependent (BOLD) signal increase. Based on this premise, the correlation of this BOLD signal increase with a particular task, such as finger-tapping, is used to map neuronal activation. This signal increase may be dampened in brain areas exhibiting impaired cerebrovascular reactivity (BOLD-CVR), leading to false negative activation. Blood-oxygenation-level-dependent (BOLD) cerebrovascular reactivity (CVR) has also been used to optimize task evoked BOLD signal changes. To measure BOLD-CVR, controlled BOLD-CVR studies have commonly been performed using a preset isocapnic carbon dioxide (CO ~40 mmHg) baseline, independent of subjects' resting CO. This arbitrary baseline, however, may influence BOLD-CVR measurements. We therefore performed BOLD-CVR, as well as BOLD fMRI during a controlled bilateral finger-tapping task in two groups of ten subjects: group A at subject's resting CO and group B at a preset isocapnic CO baseline (40 mmHg). Whole brain BOLD-CVR was significantly decreased for group B (group A 0.26 (SD 0.05) vs group B 0.16 (SD 0.05), p < 0.001). For the predefined hand area in the precentral cortex, BOLD-CVR and BOLD fMRI signal changes were significantly lower for group B (group A 0.20 (SD 0.04) vs group B 0.13 (SD 0.05), p < 0.01; 1.19 (SD 0.31) vs 0.62 (SD 0.37), p < 0.01).CO levels significantly influence both BOLD-CVR and BOLD fMRI measurements. Hence, for an accurate interpretation, baseline CO levels and BOLD CVR should be considered complementary to task evoked BOLD fMRI.

Abstract

Neurovascular coupling describes the cascade between neuronal activity and subsequent Blood-Oxygenation-Level-Dependent (BOLD) signal increase. Based on this premise, the correlation of this BOLD signal increase with a particular task, such as finger-tapping, is used to map neuronal activation. This signal increase may be dampened in brain areas exhibiting impaired cerebrovascular reactivity (BOLD-CVR), leading to false negative activation. Blood-oxygenation-level-dependent (BOLD) cerebrovascular reactivity (CVR) has also been used to optimize task evoked BOLD signal changes. To measure BOLD-CVR, controlled BOLD-CVR studies have commonly been performed using a preset isocapnic carbon dioxide (CO ~40 mmHg) baseline, independent of subjects' resting CO. This arbitrary baseline, however, may influence BOLD-CVR measurements. We therefore performed BOLD-CVR, as well as BOLD fMRI during a controlled bilateral finger-tapping task in two groups of ten subjects: group A at subject's resting CO and group B at a preset isocapnic CO baseline (40 mmHg). Whole brain BOLD-CVR was significantly decreased for group B (group A 0.26 (SD 0.05) vs group B 0.16 (SD 0.05), p < 0.001). For the predefined hand area in the precentral cortex, BOLD-CVR and BOLD fMRI signal changes were significantly lower for group B (group A 0.20 (SD 0.04) vs group B 0.13 (SD 0.05), p < 0.01; 1.19 (SD 0.31) vs 0.62 (SD 0.37), p < 0.01).CO levels significantly influence both BOLD-CVR and BOLD fMRI measurements. Hence, for an accurate interpretation, baseline CO levels and BOLD CVR should be considered complementary to task evoked BOLD fMRI.

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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Neuroradiology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:June 2018
Deposited On:31 Oct 2018 15:03
Last Modified:31 Oct 2018 15:13
Publisher:Elsevier
ISSN:0730-725X
OA Status:Closed
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1016/j.mri.2018.02.002
PubMed ID:29447850

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