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Fine tuning breath-hold-based cerebrovascular reactivity analysis models.

van Niftrik CH, Piccirelli M, Bozinov O, Pangalu A, Valavanis A, Regli L, Fierstra J - Brain Behav (2016)

Bottom Line: All models showed significant differences in CVR and coherence between the affected-hemodynamic impaired-and unaffected hemisphere.Voxel-wise phase determination significantly increases CVR (0.60 ± 0.18 vs. 0.82 ± 0.27; P < 0.05).Our CVR analysis demonstrates an improved CVR and coherence after implementation of voxel-wise phase and frequency adjustment.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery University Hospital Zurich University of Zurich Clinical Neuroscience Center Frauenklinikstrasse 10 8091 Zurich Switzerland.

ABSTRACT

Introduction: We elaborate on existing analysis methods for breath-hold (BH)-derived cerebrovascular reactivity (CVR) measurements and describe novel insights and models toward more exact CVR interpretation.

Methods: Five blood-oxygen-level-dependent (BOLD) fMRI datasets of neurovascular patients with unilateral hemispheric hemodynamic impairment were used to test various BH CVR analysis methods. Temporal lag (phase), percent BOLD signal change (CVR), and explained variance (coherence) maps were calculated using three different sine models and two novel "Optimal Signal" model-free methods based on the unaffected hemisphere and the sagittal sinus fMRI signal time series, respectively.

Results: All models showed significant differences in CVR and coherence between the affected-hemodynamic impaired-and unaffected hemisphere. Voxel-wise phase determination significantly increases CVR (0.60 ± 0.18 vs. 0.82 ± 0.27; P < 0.05). Incorporating different durations of breath hold and resting period in one sine model (two-task) did increase coherence in the unaffected hemisphere, as well as eliminating negative phase commonly obtained by one-task frequency models. The novel model-free "optimal signal" methods both explained the BOLD MR data similar to the two task sine model.

Conclusions: Our CVR analysis demonstrates an improved CVR and coherence after implementation of voxel-wise phase and frequency adjustment. The novel "optimal signal" methods provide a robust and feasible alternative to the sine models, as both are model-free and independent of compliance. Here, the sagittal sinus model may be advantageous, as it is independent of hemispheric CVR impairment.

No MeSH data available.


Related in: MedlinePlus

Illustrative models and phase, CVR, and coherence maps of one subject (male: 65 years old) with right ICA occlusion and right‐sided unilateral hemodynamic impairment on H2O‐PET imaging. The color scales are displayed below the maps. For the phase maps, the scale ranges from 0 to 60 sec. The CVR maps of the sine models display the % BOLD signal change and are ranged from −2 and 2%, whereas the “Optimal Signal” models represent the % BOLD signal change per percent optimal BOLD time series and are also ranged from −2 to 2%. The coherence maps show the measurement of the amount of variance explained with the given model between 0–1. Abbreviations: CVR, cerebrovascular reactivity; ICA, internal carotid artery; PET, positron emission tomography; TR, repetition time.
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brb3426-fig-0002: Illustrative models and phase, CVR, and coherence maps of one subject (male: 65 years old) with right ICA occlusion and right‐sided unilateral hemodynamic impairment on H2O‐PET imaging. The color scales are displayed below the maps. For the phase maps, the scale ranges from 0 to 60 sec. The CVR maps of the sine models display the % BOLD signal change and are ranged from −2 and 2%, whereas the “Optimal Signal” models represent the % BOLD signal change per percent optimal BOLD time series and are also ranged from −2 to 2%. The coherence maps show the measurement of the amount of variance explained with the given model between 0–1. Abbreviations: CVR, cerebrovascular reactivity; ICA, internal carotid artery; PET, positron emission tomography; TR, repetition time.

Mentions: Sine with the task frequency of f = 1/132 Hz and a phase shift (Fig. 2A+B).Figure 2


Fine tuning breath-hold-based cerebrovascular reactivity analysis models.

van Niftrik CH, Piccirelli M, Bozinov O, Pangalu A, Valavanis A, Regli L, Fierstra J - Brain Behav (2016)

Illustrative models and phase, CVR, and coherence maps of one subject (male: 65 years old) with right ICA occlusion and right‐sided unilateral hemodynamic impairment on H2O‐PET imaging. The color scales are displayed below the maps. For the phase maps, the scale ranges from 0 to 60 sec. The CVR maps of the sine models display the % BOLD signal change and are ranged from −2 and 2%, whereas the “Optimal Signal” models represent the % BOLD signal change per percent optimal BOLD time series and are also ranged from −2 to 2%. The coherence maps show the measurement of the amount of variance explained with the given model between 0–1. Abbreviations: CVR, cerebrovascular reactivity; ICA, internal carotid artery; PET, positron emission tomography; TR, repetition time.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834934&req=5

brb3426-fig-0002: Illustrative models and phase, CVR, and coherence maps of one subject (male: 65 years old) with right ICA occlusion and right‐sided unilateral hemodynamic impairment on H2O‐PET imaging. The color scales are displayed below the maps. For the phase maps, the scale ranges from 0 to 60 sec. The CVR maps of the sine models display the % BOLD signal change and are ranged from −2 and 2%, whereas the “Optimal Signal” models represent the % BOLD signal change per percent optimal BOLD time series and are also ranged from −2 to 2%. The coherence maps show the measurement of the amount of variance explained with the given model between 0–1. Abbreviations: CVR, cerebrovascular reactivity; ICA, internal carotid artery; PET, positron emission tomography; TR, repetition time.
Mentions: Sine with the task frequency of f = 1/132 Hz and a phase shift (Fig. 2A+B).Figure 2

Bottom Line: All models showed significant differences in CVR and coherence between the affected-hemodynamic impaired-and unaffected hemisphere.Voxel-wise phase determination significantly increases CVR (0.60 ± 0.18 vs. 0.82 ± 0.27; P < 0.05).Our CVR analysis demonstrates an improved CVR and coherence after implementation of voxel-wise phase and frequency adjustment.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery University Hospital Zurich University of Zurich Clinical Neuroscience Center Frauenklinikstrasse 10 8091 Zurich Switzerland.

ABSTRACT

Introduction: We elaborate on existing analysis methods for breath-hold (BH)-derived cerebrovascular reactivity (CVR) measurements and describe novel insights and models toward more exact CVR interpretation.

Methods: Five blood-oxygen-level-dependent (BOLD) fMRI datasets of neurovascular patients with unilateral hemispheric hemodynamic impairment were used to test various BH CVR analysis methods. Temporal lag (phase), percent BOLD signal change (CVR), and explained variance (coherence) maps were calculated using three different sine models and two novel "Optimal Signal" model-free methods based on the unaffected hemisphere and the sagittal sinus fMRI signal time series, respectively.

Results: All models showed significant differences in CVR and coherence between the affected-hemodynamic impaired-and unaffected hemisphere. Voxel-wise phase determination significantly increases CVR (0.60 ± 0.18 vs. 0.82 ± 0.27; P < 0.05). Incorporating different durations of breath hold and resting period in one sine model (two-task) did increase coherence in the unaffected hemisphere, as well as eliminating negative phase commonly obtained by one-task frequency models. The novel model-free "optimal signal" methods both explained the BOLD MR data similar to the two task sine model.

Conclusions: Our CVR analysis demonstrates an improved CVR and coherence after implementation of voxel-wise phase and frequency adjustment. The novel "optimal signal" methods provide a robust and feasible alternative to the sine models, as both are model-free and independent of compliance. Here, the sagittal sinus model may be advantageous, as it is independent of hemispheric CVR impairment.

No MeSH data available.


Related in: MedlinePlus