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Raghavan V, Sobczyk O, Sayin ES, Poublanc J, Skanda A, Duffin J, Venkatraghavan L, Fisher JA, Mikulis DJ. Assessment of Cerebrovascular Reactivity Using CO 2-BOLD MRI: A 15-Year, Single Center Experience. J Magn Reson Imaging 2024; 60:954-961. [PMID: 38135486 DOI: 10.1002/jmri.29176] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/21/2023] [Accepted: 11/22/2023] [Indexed: 12/24/2023] Open
Abstract
BACKGROUND Cerebrovascular reactivity (CVR) is a measure of the change in cerebral blood flow (CBF) in response to a vasoactive challenge. It is a useful indicator of the brain's vascular health. PURPOSE To evaluate the factors that influence successful and unsuccessful CVR examinations using precise arterial and end-tidal partial pressure of CO2 control during blood oxygen level-dependent (BOLD) MRI. STUDY TYPE Retrospective. SUBJECTS Patients that underwent a CVR between October 2005 and May 2021 were studied (total of 1162 CVR examinations). The mean (±SD) age was 46.1 (±18.8) years, and 352 patients (43%) were female. FIELD STRENGTH/SEQUENCE 3 T; T1-weighted images, T2*-weighed two-dimensional gradient-echo sequence with standard echo-planar readout. ASSESSMENT Measurements were obtained following precise hypercapnic stimuli using BOLD MRI as a surrogate of CBF. Successful CVR examinations were defined as those where: 1) patients were able to complete CVR testing, and 2) a clinically useful CVR map was generated. Unsuccessful examinations were defined as those where patients were not able to complete the CVR examination or the CVR maps were judged to be unreliable due to, for example, excessive head motion, and poor PETCO2 targeting. STATISTICAL ANALYSIS Successful and unsuccessful CVR examinations between hypercapnic stimuli, and between different patterns of stimulus were compared with Chi-Square tests. Interobserver variability was determined by using the intraclass correlation coefficient (P < 0.05 is significant). RESULTS In total 1115 CVR tests in 662 patients were included in the final analysis. The success rate of generating CVR maps was 90.8% (1012 of 1115). Among the different hypercapnic stimuli, those containing a step plus a ramp protocol was the most successful (95.18%). Among the unsuccessful examinations (9.23%), most were patient related (89.3%), the most common of which was difficulty breathing. DATA CONCLUSION CO2-BOLD MRI CVR studies are well tolerated with a high success rate. EVIDENCE LEVEL 4 TECHNICAL EFFICACY: Stage 3.
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Affiliation(s)
- Vishvak Raghavan
- School of Computer Science, McGill University, Montreal, Quebec, Canada
| | - Olivia Sobczyk
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Ontario, Canada
| | - Ece Su Sayin
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Ontario, Canada
| | - Abby Skanda
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Ontario, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Lashmi Venkatraghavan
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Joseph A Fisher
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Ontario, Canada
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Duffin J, Sayin ES, Sobczyk O, Poublanc J, Mikulis DJ, Fisher JA. Cerebral perfusion metrics calculated directly from a hypoxia-induced step change in deoxyhemoglobin. Sci Rep 2024; 14:17121. [PMID: 39054379 PMCID: PMC11272773 DOI: 10.1038/s41598-024-68047-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 07/18/2024] [Indexed: 07/27/2024] Open
Abstract
Resting cerebral perfusion metrics can be calculated from the MRI ΔR2* signal during the first passage of an intravascular bolus of a Gadolinium-based contrast agent (GBCA), or more recently, a transient hypoxia-induced change in the concentration of deoxyhemoglobin ([dOHb]). Conventional analysis follows a proxy process that includes deconvolution of an arterial input function (AIF) in a tracer kinetic model. We hypothesized that the step reduction in magnetic susceptibility accompanying a step decrease in [dOHb] that occurs when a single breath of oxygen terminates a brief episode of lung hypoxia permits direct calculation of relative perfusion metrics. The time course of the ΔR2* signal response enables both the discrimination of blood arrival times and the time course of voxel filling. We calculated the perfusion metrics implied by this step signal change in seven healthy volunteers and compared them to those from conventional analyses of GBCA and dOHb using their AIF and indicator dilution theory. Voxel-wise maps of relative cerebral blood flow and relative cerebral blood volume had a high spatial and magnitude congruence for all three analyses (r > 0.9) and were similar in appearance to published maps. The mean (SD) transit times (s) in grey and white matter respectively for the step response (7.4 (1.1), 8.05 (1.71)) were greater than those for GBCA (2.6 (0.45), 3.54 (0.83)) attributable to the nature of their respective calculation models. In conclusion we believe these calculations of perfusion metrics derived directly from ΔR2* have superior merit to calculations via AIF by virtue of being calculated from a direct signal rather than through a proxy model which encompasses errors inherent in designating an AIF and performing deconvolution calculations.
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Affiliation(s)
- James Duffin
- Department of Physiology, University of Toronto, Toronto, ON, Canada.
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, Canada.
| | - Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Olivia Sobczyk
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, Canada
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Canada
| | - Joseph A Fisher
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, Canada
- Toronto General Hospital Research Institute, University Health Network, University of Toronto, Toronto, Canada
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Caldwell HG, Hoiland RL, Bain AR, Howe CA, Carr JMJR, Gibbons TD, Durrer CG, Tymko MM, Stacey BS, Bailey DM, Sekhon MS, MacLeod DB, Ainslie PN. Evidence for direct CO 2-mediated alterations in cerebral oxidative metabolism in humans. Acta Physiol (Oxf) 2024:e14197. [PMID: 38958262 DOI: 10.1111/apha.14197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/04/2024]
Abstract
AIM How the cerebral metabolic rates of oxygen and glucose utilization (CMRO2 and CMRGlc, respectively) are affected by alterations in arterial PCO2 (PaCO2) is equivocal and therefore was the primary question of this study. METHODS This retrospective analysis involved pooled data from four separate studies, involving 41 healthy adults (35 males/6 females). Participants completed stepwise steady-state alterations in PaCO2 ranging between 30 and 60 mmHg. The CMRO2 and CMRGlc were assessed via the Fick approach (CBF × arterial-internal jugular venous difference of oxygen or glucose content, respectively) utilizing duplex ultrasound of the internal carotid artery and vertebral artery to calculate cerebral blood flow (CBF). RESULTS The CMRO2 was altered by 0.5 mL × min-1 (95% CI: -0.6 to -0.3) per mmHg change in PaCO2 (p < 0.001) which corresponded to a 9.8% (95% CI: -13.2 to -6.5) change in CMRO2 with a 9 mmHg change in PaCO2 (inclusive of hypo- and hypercapnia). The CMRGlc was reduced by 7.7% (95% CI: -15.4 to -0.08, p = 0.045; i.e., reduction in net glucose uptake) and the oxidative glucose index (ratio of oxygen to glucose uptake) was reduced by 5.6% (95% CI: -11.2 to 0.06, p = 0.049) with a + 9 mmHg increase in PaCO2. CONCLUSION Collectively, the CMRO2 is altered by approximately 1% per mmHg change in PaCO2. Further, glucose is incompletely oxidized during hypercapnia, indicating reductions in CMRO2 are either met by compensatory increases in nonoxidative glucose metabolism or explained by a reduction in total energy production.
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Affiliation(s)
- Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
| | - Anthony R Bain
- Department of Kinesiology, Faculty of Human Kinetics, University of Windsor, Windsor, Ontario, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Travis D Gibbons
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Cody G Durrer
- Centre for Physical Activity Research, Rigshospitalet, Copenhagen, Denmark
| | - Michael M Tymko
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Human Cerebrovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario, Canada
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Mypinder S Sekhon
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - David B MacLeod
- Human Pharmacology and Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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Wegener S, Baron JC, Derdeyn CP, Fierstra J, Fromm A, Klijn CJM, van Niftrik CHB, Schaafsma JD. Hemodynamic Stroke: Emerging Concepts, Risk Estimation, and Treatment. Stroke 2024; 55:1940-1950. [PMID: 38864227 DOI: 10.1161/strokeaha.123.044386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
Ischemic stroke can arise from the sudden occlusion of a brain-feeding artery by a clot (embolic), or local thrombosis. Hemodynamic stroke occurs when blood flow does not sufficiently meet the metabolic demand of a brain region at a certain time. This discrepancy between demand and supply can occur with cerebropetal arterial occlusion or high-grade stenosis but also arises with systemic conditions reducing blood pressure. Treatment of hemodynamic stroke is targeted toward increasing blood flow to the affected area by either systemically or locally enhancing perfusion. Thus, blood pressure is often maintained above normal values, and extra-intracranial flow augmentation bypass surgery is increasingly considered. Still, current evidence supporting the superiority of pressure or flow increase over conservative measures is limited. However, methods assessing hemodynamic impairment and identifying patients at risk of hemodynamic stroke are rapidly evolving. Sophisticated models incorporating clinical and imaging factors have been suggested to aid patient selection. In this narrative review, we provide current state-of-the-art knowledge about hemodynamic stroke, tools for assessment, and treatment options.
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Affiliation(s)
- Susanne Wegener
- Department of Neurology (S.W.), University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland
- Clinical Neurocenter Zurich and Neuroscience Center Zurich (ZNZ), Switzerland (S.W., J.F., C.H.B.v.N.)
| | - Jean Claude Baron
- Department of Neurology, GHU Paris Psychiatrie et Neurosciences, Hôpital Sainte-Anne, Université Paris Cité, Inserm U1266, FHU NeuroVasc, France (J.C.B.)
| | - Colin P Derdeyn
- Department of Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville (C.P.D.)
| | - Jorn Fierstra
- Department of Neurosurgery (J.F., C.H.B.v.N.), University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland
- Clinical Neurocenter Zurich and Neuroscience Center Zurich (ZNZ), Switzerland (S.W., J.F., C.H.B.v.N.)
| | - Annette Fromm
- Department of Neurology, Haukeland University Hospital, Bergen, Norway (A.F.)
| | - Catharina J M Klijn
- Department of Neurology at Radboud University Nijmegen, the Netherlands (C.J.M.K.)
| | - Christiaan Hendrik Bas van Niftrik
- Department of Neurosurgery (J.F., C.H.B.v.N.), University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland
- Clinical Neurocenter Zurich and Neuroscience Center Zurich (ZNZ), Switzerland (S.W., J.F., C.H.B.v.N.)
| | - Joanna D Schaafsma
- Division of Neurology, Department of Medicine (JDS) and Division of Neuroradiology, Department of Medical Imaging, University Health Network, Toronto, Canada (DJM, DMM) (J.D.S.)
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Weber AM, Nightingale TE, Jarrett M, Lee AHX, Campbell OL, Walter M, Lucas SJE, Phillips A, Rauscher A, Krassioukov AV. Cerebrovascular Reactivity Following Spinal Cord Injury. Top Spinal Cord Inj Rehabil 2024; 30:78-95. [PMID: 38799609 PMCID: PMC11123610 DOI: 10.46292/sci23-00068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Background Spinal cord injuries (SCI) often result in cardiovascular issues, increasing the risk of stroke and cognitive deficits. Objectives This study assessed cerebrovascular reactivity (CVR) using functional magnetic resonance imaging (fMRI) during a hypercapnic challenge in SCI participants compared to noninjured controls. Methods Fourteen participants were analyzed (n = 8 with SCI [unless otherwise noted], median age = 44 years; n = 6 controls, median age = 33 years). CVR was calculated through fMRI signal changes. Results The results showed a longer CVR component (tau) in the grey matter of SCI participants (n = 7) compared to controls (median difference = 3.0 s; p < .05). Time since injury (TSI) correlated negatively with steady-state CVR in the grey matter and brainstem of SCI participants (RS = -0.81, p = .014; RS = -0.84, p = .009, respectively). Lower steady-state CVR in the brainstem of the SCI group (n = 7) correlated with lower diastolic blood pressure (RS = 0.76, p = .046). Higher frequency of hypotensive episodes (n = 7) was linked to lower CVR outcomes in the grey matter (RS = -0.86, p = .014) and brainstem (RS = -0.89, p = .007). Conclusion Preliminary findings suggest a difference in the dynamic CVR component, tau, between the SCI and noninjured control groups, potentially explaining the higher cerebrovascular health burden in SCI individuals. Exploratory associations indicate that longer TSI, lower diastolic blood pressure, and more hypotensive episodes may lead to poorer CVR outcomes. However, further research is necessary to establish causality and support these observations.
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Affiliation(s)
- Alexander Mark Weber
- Division of Neurology, Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
- BC Children's Hospital Research Institute, Vancouver, BC, Canada
- School of Biomedical Engineering, University of British Columbia, British Columbia, Canada
- Department of Neuroscience, University of British Columbia, Vancouver, BC, Canada
| | - Tom E. Nightingale
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
- Centre for Trauma Sciences Research, University of Birmingham, Edgbaston, Birmingham, UK
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
| | - Michael Jarrett
- MRI Research Centre, University of British Columbia, Vancouver, Canada
| | - Amanda H. X. Lee
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
| | - Olivia Lauren Campbell
- BC Children's Hospital Research Institute, Vancouver, BC, Canada
- School of Biomedical Engineering, University of British Columbia, British Columbia, Canada
| | - Matthias Walter
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
- Department of Urology, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Samuel J. E. Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
- Centre for Human Brain Health, University of Birmingham, UK
| | - Aaron Phillips
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- RestoreNetwork, Hotchkiss Brain Institute, Libin Cardiovascular Institute, McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Alexander Rauscher
- Division of Neurology, Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
- BC Children's Hospital Research Institute, Vancouver, BC, Canada
- MRI Research Centre, University of British Columbia, Vancouver, Canada
- Department of Astronomy and Physics, University of British Columbia, Vancouver, BC, Canada
| | - Andrei V. Krassioukov
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
- G.F. Strong Rehabilitation Centre, Vancouver, BC, Canada
- Division of Physical Medicine and Rehabilitation, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
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van Niftrik CHB, Sebök M, Germans MR, Halter M, Pokorny T, Stumpo V, Bellomo J, Piccirelli M, Pangalu A, Katan M, Wegener S, Tymianski M, Kulcsár Z, Luft AR, Fisher JA, Mikulis DJ, Regli L, Fierstra J. Increased Risk of Recurrent Stroke in Symptomatic Large Vessel Disease With Impaired BOLD Cerebrovascular Reactivity. Stroke 2024; 55:613-621. [PMID: 38328926 DOI: 10.1161/strokeaha.123.044259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 12/11/2023] [Indexed: 02/09/2024]
Abstract
BACKGROUND Impaired cerebrovascular reactivity (CVR) has been correlated with recurrent ischemic stroke. However, for clinical purposes, most CVR techniques are rather complex, time-consuming, and lack validation for quantitative measurements. The recent adaptation of a standardized hypercapnic stimulus in combination with a blood-oxygenation-level-dependent (BOLD) magnetic resonance imaging signal as a surrogate for cerebral blood flow offers a potential universally comparable CVR assessment. We investigated the association between impaired BOLD-CVR and risk for recurrent ischemic events. METHODS We conducted a retrospective analysis of patients with symptomatic cerebrovascular large vessel disease who had undergone a prospective hypercapnic-challenged BOLD-CVR protocol at a single tertiary stroke referral center between June 2014 and April 2020. These patients were followed up for recurrent acute ischemic events for up to 3 years. BOLD-CVR (%BOLD signal change per mm Hg CO2) was calculated on a voxel-by-voxel basis. Impaired BOLD-CVR of the affected (ipsilateral to the vascular pathology) hemisphere was defined as an average BOLD-CVR, falling 2 SD below the mean BOLD-CVR of the right hemisphere in a healthy age-matched reference cohort (n=20). Using a multivariate Cox proportional hazards model, the association between impaired BOLD-CVR and ischemic stroke recurrence was assessed and Kaplan-Meier survival curves to visualize the acute ischemic stroke event rate. RESULTS Of 130 eligible patients, 28 experienced recurrent strokes (median, 85 days, interquartile range, 5-166 days). Risk factors associated with an increased recurrent stroke rate included impaired BOLD-CVR, a history of atrial fibrillation, and heart insufficiency. After adjusting for sex, age group, and atrial fibrillation, impaired BOLD-CVR exhibited a hazard ratio of 10.73 (95% CI, 4.14-27.81; P<0.001) for recurrent ischemic stroke. CONCLUSIONS Among patients with symptomatic cerebrovascular large vessel disease, those exhibiting impaired BOLD-CVR in the affected hemisphere had a 10.7-fold higher risk of recurrent ischemic stroke events compared with individuals with nonimpaired BOLD-CVR.
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Affiliation(s)
- Christiaan H B van Niftrik
- Department of Neurosurgery (C.H.B.v.N., M.S., M.R.G., M.H., V.S., J.B., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Martina Sebök
- Department of Neurosurgery (C.H.B.v.N., M.S., M.R.G., M.H., V.S., J.B., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Menno R Germans
- Department of Neurosurgery (C.H.B.v.N., M.S., M.R.G., M.H., V.S., J.B., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Matthias Halter
- Department of Neurosurgery (C.H.B.v.N., M.S., M.R.G., M.H., V.S., J.B., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Thomas Pokorny
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Department of Neurology (T.P., M.K., S.W., A.R.L.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Vittorio Stumpo
- Department of Neurosurgery (C.H.B.v.N., M.S., M.R.G., M.H., V.S., J.B., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Jacopo Bellomo
- Department of Neurosurgery (C.H.B.v.N., M.S., M.R.G., M.H., V.S., J.B., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Marco Piccirelli
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Department of Neurology (M.P., A.P., Z.K.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Athina Pangalu
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Department of Neurology (M.P., A.P., Z.K.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Mira Katan
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Department of Neurology (T.P., M.K., S.W., A.R.L.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Susanne Wegener
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Department of Neurology (T.P., M.K., S.W., A.R.L.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Michael Tymianski
- Division of Neurosurgery, Toronto Western Hospital (M.T., J.F.), University of Toronto, ON, Canada
| | - Zsolt Kulcsár
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Department of Neurology (M.P., A.P., Z.K.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Andreas R Luft
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Department of Neurology (T.P., M.K., S.W., A.R.L.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Joseph A Fisher
- Institute of Medical Science (J.A.F.), University of Toronto, ON, Canada
- Department of Anesthesia and Pain Management (J.A.F.), University Health Network, Toronto, ON, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and Functional Neuroimaging Laboratory (D.J.M.), University Health Network, Toronto, ON, Canada
| | - Luca Regli
- Department of Neurosurgery (C.H.B.v.N., M.S., M.R.G., M.H., V.S., J.B., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
| | - Jorn Fierstra
- Department of Neurosurgery (C.H.B.v.N., M.S., M.R.G., M.H., V.S., J.B., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Clinical Neuroscience Center (C.H.B.v.N., M.S., M.R.G., M.H., T.P., V.S., J.B., M.P., A.P., M.K., S.W., Z.K., A.R.L., L.R., J.F.), University Hospital of Zürich, University of Zürich, Switzerland
- Division of Neurosurgery, Toronto Western Hospital (M.T., J.F.), University of Toronto, ON, Canada
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7
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Mikulis DJ. Cerebrovascular Reserve Imaging: Problems and Solutions. Magn Reson Imaging Clin N Am 2024; 32:93-109. [PMID: 38007286 DOI: 10.1016/j.mric.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
The current standard of practice for assessing patients with cerebrovascular steno-occlusive disease is based on measuring resting blood flow metrics using MR imaging and CT perfusion imaging. However, the reliability of these methods decreases as the degree and number of stenoses increase. The reason for this is that measures of adequate baseline blood flow in highly collateralized circulations do not account for possible shortfalls in recruitable blood flow or increased metabolic demand. The following offers a clinically tested solution for this purpose using cerebrovascular reactivity methodology that applies a quantifiable vasodilatory stimulus improving reproducibility and repeatability essential for optimizing patient management.
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Affiliation(s)
- David J Mikulis
- The Krembil Brain Institute, Institute of Medcial Science, Department of Medical Imaging, The University of Toronto, The University Health Network, The Toronto Western Hospital, 399 Bathurst Street, Room 3MC-431, Toronto, ON M5T 2S8, Canada.
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8
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Sebök M, van der Wouden F, Mader C, Pangalu A, Treyer V, Fisher JA, Mikulis DJ, Hüllner M, Regli L, Fierstra J, van Niftrik CHB. Hemodynamic Failure Staging With Blood Oxygenation Level-Dependent Cerebrovascular Reactivity and Acetazolamide-Challenged ( 15O-)H 2O-Positron Emission Tomography Across Individual Cerebrovascular Territories. J Am Heart Assoc 2023; 12:e029491. [PMID: 38084716 PMCID: PMC10863778 DOI: 10.1161/jaha.123.029491] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 09/11/2023] [Indexed: 12/20/2023]
Abstract
BACKGROUND Staging of hemodynamic failure (HF) in symptomatic patients with cerebrovascular steno-occlusive disease is required to assess the risk of ischemic stroke. Since the gold standard positron emission tomography-based perfusion reserve is unsuitable as a routine clinical imaging tool, blood oxygenation level-dependent cerebrovascular reactivity (BOLD-CVR) with CO2 is a promising surrogate imaging approach. We investigated the accuracy of standardized BOLD-CVR to classify the extent of HF. METHODS AND RESULTS Patients with symptomatic unilateral cerebrovascular steno-occlusive disease, who underwent both an acetazolamide challenge (15O-)H2O-positron emission tomography and BOLD-CVR examination, were included. HF staging of vascular territories was assessed using qualitative inspection of the positron emission tomography perfusion reserve images. The optimum BOLD-CVR cutoff points between HF stages 0-1-2 were determined by comparing the quantitative BOLD-CVR data to the qualitative (15O-)H2O-positron emission tomography classification using the 3-dimensional accuracy index to the randomly assigned training and test data sets with the following determination of a single cutoff for clinical application. In the 2-case scenario, classifying data points as HF 0 or 1-2 and HF 0-1 or 2, BOLD-CVR showed an accuracy of >0.7 for all vascular territories for HF 1 and HF 2 cutoff points. In particular, the middle cerebral artery territory had an accuracy of 0.79 for HF 1 and 0.83 for HF 2, whereas the anterior cerebral artery had an accuracy of 0.78 for HF 1 and 0.82 for HF 2. CONCLUSIONS Standardized and clinically accessible BOLD-CVR examinations harbor sufficient data to provide specific cerebrovascular reactivity cutoff points for HF staging across individual vascular territories in symptomatic patients with unilateral cerebrovascular steno-occlusive disease.
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Affiliation(s)
- Martina Sebök
- Department of NeurosurgeryUniversity Hospital Zurich, University of ZurichSwitzerland
- Clinical Neuroscience CenterUniversity Hospital Zurich, University of ZurichSwitzerland
| | | | - Cäcilia Mader
- Department of Nuclear MedicineUniversity Hospital Zurich, University of ZurichSwitzerland
| | - Athina Pangalu
- Clinical Neuroscience CenterUniversity Hospital Zurich, University of ZurichSwitzerland
- Department of NeuroradiologyUniversity Hospital Zurich, University of ZurichSwitzerland
| | - Valerie Treyer
- Department of Nuclear MedicineUniversity Hospital Zurich, University of ZurichSwitzerland
| | - Joseph Arnold Fisher
- Department of Anesthesia and Pain ManagementUniversity Health NetworkTorontoOntarioCanada
- Institute of Medical ScienceUniversity of TorontoTorontoOntarioCanada
| | - David John Mikulis
- Institute of Medical ScienceUniversity of TorontoTorontoOntarioCanada
- Joint Department of Medical Imaging and the Functional Neuroimaging LaboratoryUniversity Health NetworkTorontoOntarioCanada
| | - Martin Hüllner
- Department of Nuclear MedicineUniversity Hospital Zurich, University of ZurichSwitzerland
| | - Luca Regli
- Department of NeurosurgeryUniversity Hospital Zurich, University of ZurichSwitzerland
- Clinical Neuroscience CenterUniversity Hospital Zurich, University of ZurichSwitzerland
| | - Jorn Fierstra
- Department of NeurosurgeryUniversity Hospital Zurich, University of ZurichSwitzerland
- Clinical Neuroscience CenterUniversity Hospital Zurich, University of ZurichSwitzerland
| | - Christiaan Hendrik Bas van Niftrik
- Department of NeurosurgeryUniversity Hospital Zurich, University of ZurichSwitzerland
- Clinical Neuroscience CenterUniversity Hospital Zurich, University of ZurichSwitzerland
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9
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Sayin ES, Duffin J, Poublanc J, Venkatraghavan L, Mikulis DJ, Fisher JA, Sobczyk O. Determining the effects of elevated partial pressure of oxygen on hypercapnia-induced cerebrovascular reactivity. J Cereb Blood Flow Metab 2023; 43:2085-2095. [PMID: 37632334 PMCID: PMC10925865 DOI: 10.1177/0271678x231197000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/28/2023]
Abstract
Evaluation of cerebrovascular reactivity (CVR) to hypo- and hypercapnia is a valuable test for the assessment of vasodilatory reserve. While hypercapnia-induced CVR testing is usually performed at normoxia, mild hyperoxia may increase tolerability of hypercapnia by reducing the ventilatory distress. However, the effects of mild hyperoxia on CVR was unknown. We therefore recruited 21 patients with a range of steno-occlusive diseases and 12 healthy participants who underwent a standardized 13-minute step plus ramp CVR test with a carbon dioxide gas challenge at the subject's resting end-tidal partial pressure of oxygen or at mild hyperoxia (PetO2 = 150 mmHg) depending on to which group they were assigned. In 11 patients, the second CVR test was at normoxia to examine test-retest differences. CVR was defined as % Δ Signal/ΔPetCO2. We found that there was no significant difference between CVR test results conducted at normoxia and at mild hyperoxia for participants in Groups 1 and 2 for the step and ramp portion. We also found no difference between test and retest CVR at normoxia for patients with cerebrovascular pathology (Group 3) for step and ramp portion. We concluded normoxic CVR is repeatable, and that mild hyperoxia does not affect CVR.
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Affiliation(s)
- Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Lashmikumar Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - David John Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Joseph Arnold Fisher
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Olivia Sobczyk
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
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10
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Dasari Y, Duffin J, Sayin ES, Levine HT, Poublanc J, Para AE, Mikulis DJ, Fisher JA, Sobczyk O, Khamesee MB. Convolutional Neural Networks to Assess Steno-Occlusive Disease Using Cerebrovascular Reactivity. Healthcare (Basel) 2023; 11:2231. [PMID: 37628429 PMCID: PMC10454585 DOI: 10.3390/healthcare11162231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/31/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023] Open
Abstract
Cerebrovascular Reactivity (CVR) is a provocative test used with Blood oxygenation level-dependent (BOLD) Magnetic Resonance Imaging (MRI) studies, where a vasoactive stimulus is applied and the corresponding changes in the cerebral blood flow (CBF) are measured. The most common clinical application is the assessment of cerebral perfusion insufficiency in patients with steno-occlusive disease (SOD). Globally, millions of people suffer from cerebrovascular diseases, and SOD is the most common cause of ischemic stroke. Therefore, CVR analyses can play a vital role in early diagnosis and guiding clinical treatment. This study develops a convolutional neural network (CNN)-based clinical decision support system to facilitate the screening of SOD patients by discriminating between healthy and unhealthy CVR maps. The networks were trained on a confidential CVR dataset with two classes: 68 healthy control subjects, and 163 SOD patients. This original dataset was distributed in a ratio of 80%-10%-10% for training, validation, and testing, respectively, and image augmentations were applied to the training and validation sets. Additionally, some popular pre-trained networks were imported and customized for the objective classification task to conduct transfer learning experiments. Results indicate that a customized CNN with a double-stacked convolution layer architecture produces the best results, consistent with expert clinical readings.
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Affiliation(s)
- Yashesh Dasari
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Anesthesia and Pain Management, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Anesthesia and Pain Management, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Harrison T. Levine
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Anesthesia and Pain Management, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Andrea E. Para
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON M5G 2C4, Canada
| | - David J. Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON M5G 2C4, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Joseph A. Fisher
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Anesthesia and Pain Management, University Health Network, Toronto, ON M5G 2C4, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Olivia Sobczyk
- Department of Anesthesia and Pain Management, University Health Network, Toronto, ON M5G 2C4, Canada
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Mir Behrad Khamesee
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
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11
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Ivanova MV, Pappas I. Understanding recovery of language after stroke: insights from neurovascular MRI studies. FRONTIERS IN LANGUAGE SCIENCES 2023; 2:1163547. [PMID: 38162928 PMCID: PMC10757818 DOI: 10.3389/flang.2023.1163547] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Stroke causes a disruption in blood flow to the brain that can lead to profound language impairments. Understanding the mechanisms of language recovery after stroke is crucial for the prognosis and effective rehabilitation of people with aphasia. While the role of injured brain structures and disruptions in functional connectivity have been extensively explored, the relationship between neurovascular measures and language recovery in both early and later stages has not received sufficient attention in the field. Fully functioning healthy brain tissue requires oxygen and nutrients to be delivered promptly via its blood supply. Persistent decreases in blood flow after a stroke to the remaining non-lesioned tissue have been shown to contribute to poor language recovery. The goal of the current paper is to critically examine stroke studies looking at the relationship between different neurovascular measures and language deficits and mechanisms of language recovery via changes in neurovascular metrics. Measures of perfusion or cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) provide complementary approaches to understanding neurovascular mechanisms post stroke by capturing both cerebral metabolic demands and mechanical vascular properties. While CBF measures indicate the amount of blood delivered to a certain region and serve as a proxy for metabolic demands of that area, CVR indices reflect the ability of the vasculature to recruit blood flow in response to a shortage of oxygen, such as when one is holding their breath. Increases in CBF during recovery beyond the site of the lesion have been shown to promote language gains. Similarly, CVR changes, when collateral vessels are recruited to help reorganize the flow of blood in hypoperfused regions, have been related to functional recovery post stroke. In the current review, we highlight the main findings in the literature investigating neurovascular changes in stroke recovery with a particular emphasis on how language abilities can be affected by changes in CBF and CVR. We conclude by summarizing existing methodological challenges and knowledge gaps that need to be addressed in future work in this area, outlining a promising avenue of research.
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Affiliation(s)
- Maria V. Ivanova
- Department of Psychology, University of California, Berkeley, Berkeley, CA, United States
| | - Ioannis Pappas
- USC Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, CA, United States
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12
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Sayin ES, Sobczyk O, Poublanc J, Mikulis DJ, Fisher JA, Duffin J. Transfer function analysis assesses resting cerebral perfusion metrics using hypoxia-induced deoxyhemoglobin as a contrast agent. Front Physiol 2023; 14:1167857. [PMID: 37250139 PMCID: PMC10213962 DOI: 10.3389/fphys.2023.1167857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 04/07/2023] [Indexed: 05/31/2023] Open
Abstract
Introduction: Use of contrast in determining hemodynamic measures requires the deconvolution of an arterial input function (AIF) selected over a voxel in the middle cerebral artery to calculate voxel wise perfusion metrics. Transfer function analysis (TFA) offers an alternative analytic approach that does not require identifying an AIF. We hypothesised that TFA metrics Gain, Lag, and their ratio, Gain/Lag, correspond to conventional AIF resting perfusion metrics relative cerebral blood volume (rCBV), mean transit time (MTT) and relative cerebral blood flow (rCBF), respectively. Methods: 24 healthy participants (17 M) and 1 patient with steno-occlusive disease were recruited. We used non-invasive transient hypoxia-induced deoxyhemoglobin as an MRI contrast. TFA and conventional AIF analyses were used to calculate averages of whole brain and smaller regions of interest. Results: Maps of these average metrics had colour scales adjusted to enhance contrast and identify areas of high congruence. Regional gray matter/white matter (GM/WM) ratios for MTT and Lag, rCBF and Gain/Lag, and rCBV and Gain were compared. The GM/WM ratios were greater for TFA metrics compared to those from AIF analysis indicating an improved regional discrimination. Discussion: Resting perfusion measures generated by The BOLD analysis resulting from a transient hypoxia induced variations in deoxyhemoglobin analyzed by TFA are congruent with those analyzed by conventional AIF analysis.
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Affiliation(s)
- Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Departments of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
| | - Olivia Sobczyk
- Departments of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - David J. Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - Joseph A. Fisher
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Departments of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
- Toronto General Hospital Research Institute, University Health Network, University of Toronto, Toronto, ON, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Departments of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
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13
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Sayin ES, Sobczyk O, Poublanc J, Mikulis DJ, Fisher JA, Kuo KHM, Duffin J. Assessment of cerebrovascular function in patients with sickle cell disease using transfer function analysis. Physiol Rep 2022; 10:e15472. [PMID: 36200271 PMCID: PMC9535348 DOI: 10.14814/phy2.15472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/29/2022] [Accepted: 09/01/2022] [Indexed: 11/07/2022] Open
Abstract
In patients with sickle cell disease (SCD), the delivery of oxygen to the brain is compromised by anemia, abnormal rheology, and steno‐occlusive vascular disease. Successful compensation depends on an increase in oxygen supply such as that provided by an increase in cerebral blood flow (CBF). We used magnetic resonance imaging to provide a high‐resolution assessment of the ability of SCD patients to respond to a vasoactive stimulus in middle, anterior, and posterior cerebral artery territories for both white and gray matter. Cerebrovascular reactivity (CVR) was measured as the blood oxygen level dependent signal (a surrogate for CBF) response to an increase in the end tidal partial pressure of CO2 (PETCO2). The dynamic aspect of the response was measured as the time constant of the first order response kinetics (tau). To confirm and support these findings we used an alternative examination of the response, transfer function analysis (TFA), to measure the responsiveness (gain), the speed of response (phase), and the consistency of the response over time (coherence). We tested 34 patients with SCD and compared the results to those of 24 healthy controls participants. The results from a three‐way ANOVA showed that patients with SCD have reduced CVR (p < 0.001) and lower coherence (p < 0.001) in gray matter and white matter and reduced gain in gray matter only (p < 0.001). In terms of the speed of the response to CO2, tau (p < 0.001) and TFA phase (p < 0.001) were increased in SCD patients compared to healthy control subjects. These findings show that the cerebrovascular responsiveness to CO2 in patients with SCD is both decreased and slowed compared to healthy controls.
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Affiliation(s)
- Ece Su Sayin
- Department of PhysiologyUniversity of TorontoTorontoCanada,Departments of Anaesthesia and Pain ManagementUniversity Health NetworkTorontoCanada
| | - Olivia Sobczyk
- Department of PhysiologyUniversity of TorontoTorontoCanada,Departments of Anaesthesia and Pain ManagementUniversity Health NetworkTorontoCanada,Joint Department of Medical Imaging and the Functional Neuroimaging LaboratoryUniversity Health NetworkTorontoCanada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging LaboratoryUniversity Health NetworkTorontoCanada
| | - David J. Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging LaboratoryUniversity Health NetworkTorontoCanada,Institute of Medical SciencesUniversity of TorontoTorontoCanada
| | - Joseph A. Fisher
- Department of PhysiologyUniversity of TorontoTorontoCanada,Departments of Anaesthesia and Pain ManagementUniversity Health NetworkTorontoCanada
| | - Kevin H. M. Kuo
- Division of Medical Oncology and Hematology, Department of MedicineUniversity of TorontoTorontoOntarioCanada
| | - James Duffin
- Department of PhysiologyUniversity of TorontoTorontoCanada,Departments of Anaesthesia and Pain ManagementUniversity Health NetworkTorontoCanada
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14
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Pan Y, Wan W, Xiang M, Guan Y. Transcranial Doppler Ultrasonography as a Diagnostic Tool for Cerebrovascular Disorders. Front Hum Neurosci 2022; 16:841809. [PMID: 35572008 PMCID: PMC9101315 DOI: 10.3389/fnhum.2022.841809] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 03/04/2022] [Indexed: 01/08/2023] Open
Abstract
Imaging techniques including transcranial Doppler (TCD), magnetic resonance imaging (MRI), computed tomography (CT), and cerebral angiography are available for cerebrovascular disease diagnosis. TCD is a less expensive, non-invasive, and practically simpler approach to diagnosing cerebrovascular disorders than the others. TCD is a commonly available and inexpensive diagnostic tool. However, owing to its large operator dependency, it has a narrow application area. Cerebrovascular disease indicates a group of disorders that alter the flow of blood in the brain. The brain’s functions can be temporarily or permanently impaired as a result of this change in blood flow. Timely diagnosis and treatment can restore the brain-impaired functions, resulting in a much-improved prognosis for the patients. This review summarizes the basic principles underlying the TCD imaging technique and its utility as a diagnostic tool for cerebrovascular disease.
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