Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis
In patients with carotid artery stenosis (CAS), the risk of stroke, its severity, and response to revascularization are strongly related to the availability of collateral blood flow. Unfortunately, there is poor agreement between observers in assessing collateral flow using flow-based imaging. We us...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2020-09-01
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| Series: | Frontiers in Physiology |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fphys.2020.01031/full |
| _version_ | 1818851157651488768 |
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| author | Olivia Sobczyk Olivia Sobczyk Kevin Sam Daniel M. Mandell Adrian P. Crawley Lakshmikumar Venkatraghavan Larissa McKetton Julien Poublanc James Duffin James Duffin Joseph A. Fisher Joseph A. Fisher Joseph A. Fisher David J. Mikulis David J. Mikulis |
| author_facet | Olivia Sobczyk Olivia Sobczyk Kevin Sam Daniel M. Mandell Adrian P. Crawley Lakshmikumar Venkatraghavan Larissa McKetton Julien Poublanc James Duffin James Duffin Joseph A. Fisher Joseph A. Fisher Joseph A. Fisher David J. Mikulis David J. Mikulis |
| author_sort | Olivia Sobczyk |
| collection | DOAJ |
| description | In patients with carotid artery stenosis (CAS), the risk of stroke, its severity, and response to revascularization are strongly related to the availability of collateral blood flow. Unfortunately, there is poor agreement between observers in assessing collateral flow using flow-based imaging. We used changes in blood-oxygen-level-dependent (BOLD) MRI as a surrogate of changes in regional cerebral blood flow in response to a hypercapnic stimulus [i.e., cerebrovascular reactivity (CVR)] as indicating flow reserve ipsilateral to CAS. We hypothesized that some patients with hemodynamically significant CAS develop functional collateral flow as indicated by normalization of ipsilateral CVR. We identified 55 patients in our CVR database with various degrees of CAS assessed by angiography and classed them as <50% stenosis, 50–69% stenosis, 70–90% stenosis, >90% stenosis, and full occlusion. CVR was measured as the change in BOLD signal in response to changes in end-tidal partial pressure of CO2 (Δ BOLD/Δ PETCO2) and normalized voxel-wise relative to the mean and standard deviation of the CVR in the corresponding voxels of an atlas of 46 healthy controls (CVR z scores). CVR and z scores were then averaged over gray matter (GM) and white matter (WM) on each side of the middle cerebral artery (MCA) territory. As hypothesized, CVR varied for each severity of CAS. Ipsilateral MCA territory CVR was less than normal in each class, including that with <50% stenosis (Student t-test, two-tailed; p = 0.0014 for GM and p = 0.030 for WM), with a trend of decreasing average CVR with increasing stenosis. Remarkably, the considerable individual variability in MCA CVR included some patients with normal CVR in each class – including that with complete occlusion. We conclude that, in general, CAS depresses downstream vascular reserve, but the extent of collateralization is highly variable and not predictable from the degree of stenosis, including both <50% stenosis and complete occlusion. CVR may be the more reliable marker for recruitable collateral blood flow than degree of CAS. |
| first_indexed | 2024-12-19T07:00:34Z |
| format | Article |
| id | doaj.art-d79da084ea81443bb51f37ad6c45723e |
| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-12-19T07:00:34Z |
| publishDate | 2020-09-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Physiology |
| spelling | doaj.art-d79da084ea81443bb51f37ad6c45723e2022-12-21T20:31:26ZengFrontiers Media S.A.Frontiers in Physiology1664-042X2020-09-011110.3389/fphys.2020.01031569390Cerebrovascular Reactivity Assays Collateral Function in Carotid StenosisOlivia Sobczyk0Olivia Sobczyk1Kevin Sam2Daniel M. Mandell3Adrian P. Crawley4Lakshmikumar Venkatraghavan5Larissa McKetton6Julien Poublanc7James Duffin8James Duffin9Joseph A. Fisher10Joseph A. Fisher11Joseph A. Fisher12David J. Mikulis13David J. Mikulis14Institute of Medical Science, University of Toronto, Toronto, ON, CanadaJoint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, CanadaJoint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, CanadaJoint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, CanadaJoint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, CanadaDepartment of Anaesthesia and Pain Management, University Health Network, Toronto, ON, CanadaJoint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, CanadaJoint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, CanadaDepartment of Anaesthesia and Pain Management, University Health Network, Toronto, ON, CanadaDepartment of Physiology, University of Toronto, Toronto, ON, CanadaInstitute of Medical Science, University of Toronto, Toronto, ON, CanadaDepartment of Anaesthesia and Pain Management, University Health Network, Toronto, ON, CanadaDepartment of Physiology, University of Toronto, Toronto, ON, CanadaInstitute of Medical Science, University of Toronto, Toronto, ON, CanadaJoint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, CanadaIn patients with carotid artery stenosis (CAS), the risk of stroke, its severity, and response to revascularization are strongly related to the availability of collateral blood flow. Unfortunately, there is poor agreement between observers in assessing collateral flow using flow-based imaging. We used changes in blood-oxygen-level-dependent (BOLD) MRI as a surrogate of changes in regional cerebral blood flow in response to a hypercapnic stimulus [i.e., cerebrovascular reactivity (CVR)] as indicating flow reserve ipsilateral to CAS. We hypothesized that some patients with hemodynamically significant CAS develop functional collateral flow as indicated by normalization of ipsilateral CVR. We identified 55 patients in our CVR database with various degrees of CAS assessed by angiography and classed them as <50% stenosis, 50–69% stenosis, 70–90% stenosis, >90% stenosis, and full occlusion. CVR was measured as the change in BOLD signal in response to changes in end-tidal partial pressure of CO2 (Δ BOLD/Δ PETCO2) and normalized voxel-wise relative to the mean and standard deviation of the CVR in the corresponding voxels of an atlas of 46 healthy controls (CVR z scores). CVR and z scores were then averaged over gray matter (GM) and white matter (WM) on each side of the middle cerebral artery (MCA) territory. As hypothesized, CVR varied for each severity of CAS. Ipsilateral MCA territory CVR was less than normal in each class, including that with <50% stenosis (Student t-test, two-tailed; p = 0.0014 for GM and p = 0.030 for WM), with a trend of decreasing average CVR with increasing stenosis. Remarkably, the considerable individual variability in MCA CVR included some patients with normal CVR in each class – including that with complete occlusion. We conclude that, in general, CAS depresses downstream vascular reserve, but the extent of collateralization is highly variable and not predictable from the degree of stenosis, including both <50% stenosis and complete occlusion. CVR may be the more reliable marker for recruitable collateral blood flow than degree of CAS.https://www.frontiersin.org/article/10.3389/fphys.2020.01031/fullcerebrovascular reactivitycollateralscerebral blood flowcerebrovascular diseasestrokeMRI |
| spellingShingle | Olivia Sobczyk Olivia Sobczyk Kevin Sam Daniel M. Mandell Adrian P. Crawley Lakshmikumar Venkatraghavan Larissa McKetton Julien Poublanc James Duffin James Duffin Joseph A. Fisher Joseph A. Fisher Joseph A. Fisher David J. Mikulis David J. Mikulis Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis Frontiers in Physiology cerebrovascular reactivity collaterals cerebral blood flow cerebrovascular disease stroke MRI |
| title | Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis |
| title_full | Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis |
| title_fullStr | Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis |
| title_full_unstemmed | Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis |
| title_short | Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis |
| title_sort | cerebrovascular reactivity assays collateral function in carotid stenosis |
| topic | cerebrovascular reactivity collaterals cerebral blood flow cerebrovascular disease stroke MRI |
| url | https://www.frontiersin.org/article/10.3389/fphys.2020.01031/full |
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