Cerebrovascular reactivity mapping without hypercapnic challenge in patients with carotid artery stenosis

Secchinato, Kaio Felippe; Silva, Pedro Henrique Rodrigues da; Camargo, Ana; Pontes-Neto, Octávio M.; Leoni, Renata Ferranti

doi:10.29384/rbfm.2019.v13.n2.p62-65

Cited by 4 publications

(7 citation statements)

References 13 publications

(15 reference statements)

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“…This may be favored in clinical studies where subject compliance with breathing tasks is hard to achieve. The utility of this resting-state CVR approach has also been demonstrated in clinical cohorts [32], [34]–[37].…”

Section: Introductionmentioning

confidence: 99%

A practical modification to a resting state fMRI protocol for improved characterization of cerebrovascular function

Stickland

Zvolanek

Moia

et al. 2021

Preprint

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Cerebrovascular reactivity (CVR), defined here as the Blood Oxygenation Level Dependent (BOLD) response to a CO2 pressure change, is a useful metric of cerebrovascular function. Both the amplitude and the timing (hemodynamic lag) of the CVR response can bring insight into the nature of a cerebrovascular pathology and aid in understanding noise confounds when using functional Magnetic Resonance Imaging (fMRI) to study neural activity. This research assessed a practical modification to a typical resting state fMRI protocol, to improve the characterization of cerebrovascular function. In 9 healthy subjects, we modelled CVR and lag in three resting state data segments, and in data segments which added a 2 to 3 minute breathing task to the start of a resting state segment. Two different breathing tasks were used to induce fluctuations in arterial CO2 pressure: a breath hold task to induce hypercapnia (CO2 increase) and a cued deep breathing task to induce hypocapnia (CO2 decrease). Our analysis produced voxelwise estimates of the amplitude (CVR) and timing (lag) of the BOLD fMRI response to CO2 by systematically shifting the CO2 regressor in time to optimize the model fit. This optimization inherently increases grey matter CVR values and fit statistics. The inclusion of a simple breathing task, compared to a resting state scan only, increases the number of voxels in the brain that have a significant relationship between CO2 and BOLD fMRI signals, and improves our confidence in the plausibility of voxelwise CVR and hemodynamic lag estimates. We demonstrate the clinical utility and feasibility of this protocol in an incidental finding of Moyamoya disease, and explore the possibilities and challenges of using this protocol in younger populations. This hybrid protocol has direct applications for CVR mapping in both research and clinical settings and wider applications for fMRI denoising and interpretation.

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Section: Introductionmentioning

confidence: 99%

A practical modification to a resting state fMRI protocol for improved characterization of cerebrovascular function

Stickland

Zvolanek

Moia

et al. 2021

Preprint

View full text Add to dashboard Cite

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“…(*p < 0.05; **p < 0.01; ***p < 0.001). Figura adaptada de Secchinato e colaboradores (SECCHINATO et al, 2019) A Figura 11 mostra os resultados para quatro pacientes representativos. Os coeficientes de correlação de Pearson entre os valores de rs-CVR e CVR com CO 2 foram superiores a 0,60 para todos os participantes.…”

Section: Resultsunclassified

“…Na primeira parte do estudo, buscamos verificar a banda de frequência mais adequada para filtrar o sinal BOLD em estado de repouso a fim de obter mapas de rs-CVR similares aqueles obtidos sob hipercapnia (pausa respiratória e inalação de CO 2 ). Nos últimos anos, estudos têm mostrado que o sinal BOLD em estado de repouso em baixas frequências possui informações relacionadas às mudanças de PETCO 2 (LIU et al, 2017;TANEJA et al, 2019;JAHANIAN et al, 2014;WISE et al, 2004;SECCHINATO et al, 2019), sugerindo uma alternativa para a avaliação de CVR. Entretanto, esses estudos não fizeram essa avaliação em idosos, como realizado no presente estudo.…”

Section: Discussionunclassified

“…Porém, visualmente, a filtragem na frequência de 0,02-0,04 Hz forneceu os mapas de CVR mais similares com o mapa de pausa repsiratória, do que as outras bandas analisadas. Essa mesma faixa de frequências foi utilizada em estudos anteriores (LIU et al, 2017;TANEJA et al, 2019;SECCHINATO et al, 2019).…”

Section: Discussionunclassified

“…Adaptada de Lu e colaboradores(LU et al, 2014).Para experimentos de inalação de CO 2 , a entrega do estímulo pode acontecer de várias formas diferentes, mas o mais utilizado é o paradigma em bloco. Nessa metodologia os blocos de ar ambiente e gás hipercápnico são fornecidos ao sujeito de maneira intercalada, onde a duração do bloco hipercápnico pode variar de 14 segundos(SECCHINATO et al, 2019) até 2-3 minutos (TANCREDI; HOGE, 2013), e a duração dos blocos de ar ambiente pode…”

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Mapeamento da vasorreatividade cerebral sem estímulo vasoativo: um estudo de imagens em estado de repouso

Secchinato¹

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Cerebrovascular reactivity (CVR) represents the ability of the vascular smooth muscle to dilate or contract in response to changes in metabolic demand changes or vasoactive stimuli to regulate cerebral blood flow when necessary. This response can be affected in several neurological diseases, mainly cerebrovascular diseases, both in magnitude and in time delay. The latter is observed as a temporal shift (TS) of the response. Such measures are valuable to report the hemodynamic state of the brain and are of interest in several studies trying to predict the risk of stroke, such as in patients with carotid artery stenosis. However, standard methods require specific conditions, such as administering acetazolamide or inhalation of CO 2 while magnetic resonance images (MRI) are acquired. In the present study, we evaluated CVR and TS from fluctuations in the MRI signal based on the blood oxygenation-dependent contrast (BOLD) at rest, without performing hypercapnia challenges. In the first part of the study, we identified an adequate frequency range for temporal filtering of the resting-state signal to obtain CVR maps, based on the spatial correlation with standard CVR maps obtained with CO 2 inhalation and breath-holding. Five patients with unilateral severe asymptomatic carotid stenosis (70 ± 3 years) and five controls (65 ± 3 years) performed the experiment with CO 2 inhalation, and 23 healthy elderly (67 ± 6 years) performed the experiment with breath-holding. CVR maps obtained through the general linear regression model showed a more significant spatial correlation when using the regressor of the global signal filtered at 0.02 to 0.04 Hz when compared with reference maps. Thus, this frequency band was used for the second part of the study, in which we evaluated CVR and TS in 20 patients with unilateral severe asymptomatic carotid stenosis (12 women; 8 men; mean age = 67 ± 10 years) comparing with a group of healthy control (8 women; 12 men; mean age = 68 ± seven years). In patients, reduced CVR values were observed bilaterally in regions irrigated by the intermediary portion of the anterior cerebral artery (ACA) when compared to the proximal portion and for the proximal, middle cerebral artery (MCA) when compared to the distal (p < 0.05). TS values were higher in patients in the three portions of the MCA territory and the distal portion of the posterior cerebral artery (PCA) territory, in the hemisphere ipsilateral to the stenosis, when compared to the corresponding regions of the control group (p < 0.04 ). In addition, in patients, TS was higher in the distal MCA ipsilateral to the stenosis compared to the same region in the contralateral hemisphere (p = 0.0025). Similar regional changes in CVR and TS were observed when visually analyzing individual maps suggesting that the methodologies are complementary. These parameters may reflect subclinical hemodynamic changes and help investigate areas with a higher risk of neuronal damage or ischemic stroke at an individual level. Therefore, the study of cerebral hemodynamic...

show abstract

A practical modification to a resting state fMRI protocol for improved characterization of cerebrovascular function

et al. 2021

View full text Add to dashboard Cite

Cerebrovascular reactivity (CVR), defined here as the Blood Oxygenation Level Dependent (BOLD) response to a CO 2 pressure change, is a useful metric of cerebrovascular function. Both the amplitude and the timing (hemodynamic lag) of the CVR response can bring insight into the nature of a cerebrovascular pathology and aid in understanding noise confounds when using functional Magnetic Resonance Imaging (fMRI) to study neural activity. This research assessed a practical modification to a typical resting-state fMRI protocol, to improve the characterization of cerebrovascular function. In 9 healthy subjects, we modelled CVR and lag in three resting-state data segments, and in data segments which added a 2–3 minute breathing task to the start of a resting-state segment. Two different breathing tasks were used to induce fluctuations in arterial CO 2 pressure: a breath-hold task to induce hypercapnia (CO 2 increase) and a cued deep breathing task to induce hypocapnia (CO 2 decrease). Our analysis produced voxel-wise estimates of the amplitude (CVR) and timing (lag) of the BOLD-fMRI response to CO 2 by systematically shifting the CO 2 regressor in time to optimize the model fit. This optimization inherently increases gray matter CVR values and fit statistics. The inclusion of a simple breathing task, compared to a resting-state scan only, increases the number of voxels in the brain that have a significant relationship between CO 2 and BOLD-fMRI signals, and improves our confidence in the plausibility of voxel-wise CVR and hemodynamic lag estimates. We demonstrate the clinical utility and feasibility of this protocol in an incidental finding of Moyamoya disease, and explore the possibilities and challenges of using this protocol in younger populations. This hybrid protocol has direct applications for CVR mapping in both research and clinical settings and wider applications for fMRI denoising and interpretation.

show abstract

Cerebrovascular reactivity mapping without hypercapnic challenge in patients with carotid artery stenosis

Cited by 4 publications

References 13 publications

A practical modification to a resting state fMRI protocol for improved characterization of cerebrovascular function

A practical modification to a resting state fMRI protocol for improved characterization of cerebrovascular function

Mapeamento da vasorreatividade cerebral sem estímulo vasoativo: um estudo de imagens em estado de repouso

A practical modification to a resting state fMRI protocol for improved characterization of cerebrovascular function

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