Cerebrovascular reactivity mapping using intermittent breath modulation

Cerebrovascular reactivity (CVR), an index of brain vessel’s dilatory capacity, is typically measured using hypercapnic gas inhalation or breath-holding as a vasoactive challenge. However, these methods require considerable subject cooperation and could be challenging in clinical studies. More recen...

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Main Authors: Peiying Liu, Cuimei Xu, Zixuan Lin, Sandeepa Sur, Yang Li, Sevil Yasar, Paul Rosenberg, Marilyn Albert, Hanzhang Lu
Format: Article
Language:English
Published: Elsevier 2020-07-01
Series:NeuroImage
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S1053811920302743
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author Peiying Liu
Cuimei Xu
Zixuan Lin
Sandeepa Sur
Yang Li
Sevil Yasar
Paul Rosenberg
Marilyn Albert
Hanzhang Lu
author_facet Peiying Liu
Cuimei Xu
Zixuan Lin
Sandeepa Sur
Yang Li
Sevil Yasar
Paul Rosenberg
Marilyn Albert
Hanzhang Lu
author_sort Peiying Liu
collection DOAJ
description Cerebrovascular reactivity (CVR), an index of brain vessel’s dilatory capacity, is typically measured using hypercapnic gas inhalation or breath-holding as a vasoactive challenge. However, these methods require considerable subject cooperation and could be challenging in clinical studies. More recently, there have been attempts to use resting-state BOLD data to map CVR by utilizing spontaneous changes in breathing pattern. However, in subjects who have small fluctuations in their spontaneous breathing pattern, the CVR results could be noisy and unreliable. In this study, we aim to develop a new method for CVR mapping that does not require gas-inhalation yet provides substantially higher sensitivity than resting-state CVR mapping. This new method is largely based on resting-state scan, but introduces intermittent modulation of breathing pattern in the subject to enhance fluctuations in their end-tidal CO2 (EtCO2) level. Here we examined the comfort level, sensitivity, and accuracy of this method in two studies. First, in 8 healthy young subjects, we developed the intermittent breath-modulation method using two different modulation frequencies, 6 ​s per breath and 12 ​s per breath, respectively, and compared the results to three existing CVR methods, specifically hypercapnic gas inhalation, breath-holding, and resting-state. Our results showed that the comfort level of the 6-s breath-modulation method was significantly higher than breath-holding (p ​= ​0.007) and CO2-inhalation (p ​= ​0.015) methods, while not different from the resting-state, i.e. free breathing method (p ​= ​0.52). When comparing the sensitivity of CVR methods, the breath-modulation methods revealed higher Z-statistics compared to the resting-state scan (p ​< ​0.008) and was comparable to breath-holding results. Next, we tested the feasibility of breath-modulation CVR mapping (6 ​s per breath) in 21 cognitively normal elderly participants and compared quantitative CVR values to that obtained with the CO2-inhalation method. Whole-brain CVR was found to be 0.150 ​± ​0.055 and 0.154 ​± ​0.032 %ΔBOLD/mmHg for the breath-modulation and CO2-inhalation method, respectively, with a significant correlation between them (y ​= ​0.97x, p ​= ​0.007). CVR mapping with intermittent breath modulation may be a useful method that combines the advantages of resting-state and CO2-inhalation based approaches.
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spelling doaj.art-aac60e7eb12e4e58bbcef6780c54c7e62022-12-21T23:36:32ZengElsevierNeuroImage1095-95722020-07-01215116787Cerebrovascular reactivity mapping using intermittent breath modulationPeiying Liu0Cuimei Xu1Zixuan Lin2Sandeepa Sur3Yang Li4Sevil Yasar5Paul Rosenberg6Marilyn Albert7Hanzhang Lu8Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Corresponding author. Department of Radiology, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Park 324, Baltimore, MD, 21287, USA.Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USADepartment of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USADepartment of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USADepartment of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USADepartment of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USADepartment of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USADepartment of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USADepartment of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USACerebrovascular reactivity (CVR), an index of brain vessel’s dilatory capacity, is typically measured using hypercapnic gas inhalation or breath-holding as a vasoactive challenge. However, these methods require considerable subject cooperation and could be challenging in clinical studies. More recently, there have been attempts to use resting-state BOLD data to map CVR by utilizing spontaneous changes in breathing pattern. However, in subjects who have small fluctuations in their spontaneous breathing pattern, the CVR results could be noisy and unreliable. In this study, we aim to develop a new method for CVR mapping that does not require gas-inhalation yet provides substantially higher sensitivity than resting-state CVR mapping. This new method is largely based on resting-state scan, but introduces intermittent modulation of breathing pattern in the subject to enhance fluctuations in their end-tidal CO2 (EtCO2) level. Here we examined the comfort level, sensitivity, and accuracy of this method in two studies. First, in 8 healthy young subjects, we developed the intermittent breath-modulation method using two different modulation frequencies, 6 ​s per breath and 12 ​s per breath, respectively, and compared the results to three existing CVR methods, specifically hypercapnic gas inhalation, breath-holding, and resting-state. Our results showed that the comfort level of the 6-s breath-modulation method was significantly higher than breath-holding (p ​= ​0.007) and CO2-inhalation (p ​= ​0.015) methods, while not different from the resting-state, i.e. free breathing method (p ​= ​0.52). When comparing the sensitivity of CVR methods, the breath-modulation methods revealed higher Z-statistics compared to the resting-state scan (p ​< ​0.008) and was comparable to breath-holding results. Next, we tested the feasibility of breath-modulation CVR mapping (6 ​s per breath) in 21 cognitively normal elderly participants and compared quantitative CVR values to that obtained with the CO2-inhalation method. Whole-brain CVR was found to be 0.150 ​± ​0.055 and 0.154 ​± ​0.032 %ΔBOLD/mmHg for the breath-modulation and CO2-inhalation method, respectively, with a significant correlation between them (y ​= ​0.97x, p ​= ​0.007). CVR mapping with intermittent breath modulation may be a useful method that combines the advantages of resting-state and CO2-inhalation based approaches.http://www.sciencedirect.com/science/article/pii/S1053811920302743Cerebrovascular reactivityResting-state BOLD fMRIBreath modulationEnd-tidal CO2Hypercapnia
spellingShingle Peiying Liu
Cuimei Xu
Zixuan Lin
Sandeepa Sur
Yang Li
Sevil Yasar
Paul Rosenberg
Marilyn Albert
Hanzhang Lu
Cerebrovascular reactivity mapping using intermittent breath modulation
NeuroImage
Cerebrovascular reactivity
Resting-state BOLD fMRI
Breath modulation
End-tidal CO2
Hypercapnia
title Cerebrovascular reactivity mapping using intermittent breath modulation
title_full Cerebrovascular reactivity mapping using intermittent breath modulation
title_fullStr Cerebrovascular reactivity mapping using intermittent breath modulation
title_full_unstemmed Cerebrovascular reactivity mapping using intermittent breath modulation
title_short Cerebrovascular reactivity mapping using intermittent breath modulation
title_sort cerebrovascular reactivity mapping using intermittent breath modulation
topic Cerebrovascular reactivity
Resting-state BOLD fMRI
Breath modulation
End-tidal CO2
Hypercapnia
url http://www.sciencedirect.com/science/article/pii/S1053811920302743
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