1
|
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.
Collapse
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
| |
Collapse
|
2
|
Marchena-Romero KJ, Ji X, Sommer R, Centen A, Ramirez J, Poulin JM, Mikulis D, Thrippleton M, Wardlaw J, Lim A, Black SE, MacIntosh BJ. Examining temporal features of BOLD-based cerebrovascular reactivity in clinical populations. Front Neurol 2023; 14:1199805. [PMID: 37396759 PMCID: PMC10310960 DOI: 10.3389/fneur.2023.1199805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 05/25/2023] [Indexed: 07/04/2023] Open
Abstract
Background Conventional cerebrovascular reactivity (CVR) estimation has demonstrated that many brain diseases and/or conditions are associated with altered CVR. Despite the clinical potential of CVR, characterization of temporal features of a CVR challenge remains uncommon. This work is motivated by the need to develop CVR parameters that characterize individual temporal features of a CVR challenge. Methods Data were collected from 54 adults and recruited based on these criteria: (1) Alzheimer's disease diagnosis or subcortical Vascular Cognitive Impairment, (2) sleep apnea, and (3) subjective cognitive impairment concerns. We investigated signal changes in blood oxygenation level dependent (BOLD) contrast images with respect to hypercapnic and normocapnic CVR transition periods during a gas manipulation paradigm. We developed a model-free, non-parametric CVR metric after considering a range of responses through simulations to characterize BOLD signal changes that occur when transitioning from normocapnia to hypercapnia. The non-parametric CVR measure was used to examine regional differences across the insula, hippocampus, thalamus, and centrum semiovale. We also examined the BOLD signal transition from hypercapnia back to normocapnia. Results We found a linear association between isolated temporal features of successive CO2 challenges. Our study concluded that the transition rate from hypercapnia to normocapnia was significantly associated with the second CVR response across all regions of interest (p < 0.001), and this association was highest in the hippocampus (R2 = 0.57, p < 0.0125). Conclusion This study demonstrates that it is feasible to examine individual responses associated with normocapnic and hypercapnic transition periods of a BOLD-based CVR experiment. Studying these features can provide insight on between-subject differences in CVR.
Collapse
Affiliation(s)
- Kayley-Jasmin Marchena-Romero
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Xiang Ji
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
| | - Rosa Sommer
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Andrew Centen
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Joel Ramirez
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
| | - Joshua M. Poulin
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
| | - David Mikulis
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
- Division of Neuroradiology, Joint Department of Medical Imaging, University Health Network, Toronto, ON, Canada
- Department of Medical Imaging, University of Toronto, Toronto, ON, Canada
| | - Michael Thrippleton
- Brain Research Imaging Centre, Centre for Clinical Brain Sciences, UK Dementia Research Institute Centre, The University of Edinburgh, Edinburgh, United Kingdom
| | - Joanna Wardlaw
- Brain Research Imaging Centre, Centre for Clinical Brain Sciences, UK Dementia Research Institute Centre, The University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew Lim
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Sandra E. Black
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
| | - Bradley J. MacIntosh
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
| |
Collapse
|
3
|
Fitzgerald B, Yao JF, Hocke LM, Frederick BD, van Niftrik CHB, Tong Y. Using carpet plots to analyze blood transit times in the brain during hypercapnic challenge magnetic resonance imaging. Front Physiol 2023; 14:1134804. [PMID: 36875021 PMCID: PMC9975721 DOI: 10.3389/fphys.2023.1134804] [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: 12/30/2022] [Accepted: 02/01/2023] [Indexed: 02/17/2023] Open
Abstract
Blood arrival time and blood transit time are useful metrics in characterizing hemodynamic behaviors in the brain. Functional magnetic resonance imaging in combination with a hypercapnic challenge has been proposed as a non-invasive imaging tool to determine blood arrival time and replace dynamic susceptibility contrast (DSC) magnetic resonance imaging, a current gold-standard imaging tool with the downsides of invasiveness and limited repeatability. Using a hypercapnic challenge, blood arrival times can be computed by cross-correlating the administered CO2 signal with the fMRI signal, which increases during elevated CO2 due to vasodilation. However, whole-brain transit times derived from this method can be significantly longer than the known cerebral transit time for healthy subjects (nearing 20 s vs. the expected 5-6 s). To address this unrealistic measurement, we here propose a novel carpet plot-based method to compute improved blood transit times derived from hypercapnic blood oxygen level dependent fMRI, demonstrating that the method reduces estimated blood transit times to an average of 5.32 s. We also investigate the use of hypercapnic fMRI with cross-correlation to compute the venous blood arrival times in healthy subjects and compare the computed delay maps with DSC-MRI time to peak maps using the structural similarity index measure (SSIM). The strongest delay differences between the two methods, indicated by low structural similarity index measure, were found in areas of deep white matter and the periventricular region. SSIM measures throughout the remainder of the brain reflected a similar arrival sequence derived from the two methods despite the exaggerated spread of voxel delays computed using CO2 fMRI.
Collapse
Affiliation(s)
- Bradley Fitzgerald
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, United States
| | - Jinxia Fiona Yao
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Lia M Hocke
- McLean Imaging Center, McLean Hospital, Belmont, MA, United States.,Department of Psychiatry, Harvard Medical School, Boston, MA, , United States
| | - Blaise deB Frederick
- McLean Imaging Center, McLean Hospital, Belmont, MA, United States.,Department of Psychiatry, Harvard Medical School, Boston, MA, , United States
| | | | - Yunjie Tong
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| |
Collapse
|
4
|
Shams S, Prokopiou P, Esmaelbeigi A, Mitsis GD, Chen JJ. Modeling the dynamics of cerebrovascular reactivity to carbon dioxide in fMRI under task and resting-state conditions. Neuroimage 2023; 265:119758. [PMID: 36442732 DOI: 10.1016/j.neuroimage.2022.119758] [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: 07/06/2022] [Revised: 11/11/2022] [Accepted: 11/18/2022] [Indexed: 11/26/2022] Open
Abstract
Conventionally, cerebrovascular reactivity (CVR) is estimated as the amplitude of the hemodynamic response to vascular stimuli, most commonly carbon dioxide (CO2). While the CVR amplitude has established clinical utility, the temporal characteristics of CVR (dCVR) have been increasingly explored and may yield even more pathology-sensitive parameters. This work is motivated by the current need to evaluate the feasibility of dCVR modeling in various experimental conditions. In this work, we present a comparison of several recently published/utilized model-based deconvolution (response estimation) approaches for estimating the CO2 response function h(t), including maximum a posteriori likelihood (MAP), inverse logit (IL), canonical correlation analysis (CCA), and basis expansion (using Gamma and Laguerre basis sets). To aid the comparison, we devised a novel simulation framework that incorporates a wide range of SNRs, ranging from 10 to -7 dB, representative of both task and resting-state CO2 changes. In addition, we built ground-truth h(t) into our simulation framework, overcoming the conventional limitation that the true h(t) is unknown. Moreover, to best represent realistic noise found in fMRI scans, we extracted noise from in-vivo resting-state scans. Furthermore, we introduce a simple optimization of the CCA method (CCAopt) and compare its performance to these existing methods. Our findings suggest that model-based methods can accurately estimate dCVR even amidst high noise (i.e. resting-state), and in a manner that is largely independent of the underlying model assumptions for each method. We also provide a quantitative basis for making methodological choices, based on the desired dCVR parameters, the estimation accuracy and computation time. The BEL method provided the highest accuracy and robustness, followed by the CCAopt and IL methods. Of the three, the CCAopt method has the lowest computational requirements. These findings lay the foundation for wider adoption of dCVR estimation in CVR mapping.
Collapse
Affiliation(s)
- Seyedmohammad Shams
- Rotman Research Institute, Baycrest Health Sciences, Canada; Department of Neurology, Henry Ford Health, USA
| | - Prokopis Prokopiou
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | | | | | - J Jean Chen
- Rotman Research Institute, Baycrest Health Sciences, Canada; Department of Bioengineering, McGill University, Canada; Department of Medical Biophysics, University of Toronto, Canada; Institute of Biomedical Engineering, University of Toronto, Canada.
| |
Collapse
|
5
|
Sayin ES, Sobczyk O, Poublanc J, Mikulis DJ, Fisher JA, Kuo KHM, Duffin J. Assessing Cerebrovascular Resistance in Patients With Sickle Cell Disease. Front Physiol 2022; 13:847969. [PMID: 35422710 PMCID: PMC9002264 DOI: 10.3389/fphys.2022.847969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/08/2022] [Indexed: 02/05/2023] 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. Meeting demands for oxygen delivery requires compensatory features of brain perfusion. The cerebral vasculature’s regulatory function and reserves can be assessed by observing the flow response to a vasoactive stimulus. In a traditional approach we measured voxel-wise change in Blood Oxygen-Level Dependent (BOLD) MRI signal as a surrogate of cerebral blood flow (CBF) in response to a linear progressive ramping of end-tidal partial pressure of carbon dioxide (PETCO2). Cerebrovascular reactivity (CVR) was defined as ΔBOLD/ΔPETCO2. We used a computer model to fit a virtual sigmoid resistance curve to the progressive CBF response to the stimulus, enabling the calculation of resistance parameters: amplitude, midpoint, range response, resistance sensitivity and vasodilatory reserve. The quality of the resistance sigmoid fit was expressed as the r2 of the fit. We tested 35 patients with SCD, as well as 24 healthy subjects to provide an indication of the normal ranges of the resistance parameters. We found that gray matter CVR and resistance amplitude, range, reserve, and sensitivity are reduced in patients with SCD compared to healthy controls, while resistance midpoint was increased. This study is the first to document resistance measures in adult patients with SCD. It is also the first to score these vascular resistance measures in comparison to the normal range. We anticipate these data will complement the current understanding of the cerebral vascular pathophysiology of SCD, identify paths for therapeutic interventions, and provide biomarkers for monitoring the progress of the disease.
Collapse
Affiliation(s)
- Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
| | - Olivia Sobczyk
- Department 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
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Joseph A. Fisher
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Kevin H. M. Kuo
- Division of Hematology, Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
- *Correspondence: James Duffin,
| |
Collapse
|
6
|
Wang R, Poublanc J, Crawley AP, Sobczyk O, Kneepkens S, Mcketton L, Tator C, Wu R, Mikulis DJ. Cerebrovascular reactivity changes in acute concussion: a controlled cohort study. Quant Imaging Med Surg 2021; 11:4530-4542. [PMID: 34737921 DOI: 10.21037/qims-20-1296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 06/18/2021] [Indexed: 11/06/2022]
Abstract
Background Evidence suggests that cerebrovascular reactivity (CVR) increases within the first week after the incidence of concussion, indicating a disruption of normal autoregulation. We sought to extend these findings by investigating the effects of acute concussion on the speed of CVR response and by visualizing global and regional impairments in individual patients with acute concussion. Methods Twelve patients aged 18-40 years who experienced concussion less than a week before this prospective study were included. Twelve age and sex-matched healthy subjects constituted the control group. In all subjects, CVR was assessed using blood oxygenation level-dependent (BOLD) echo-planar imaging with a 3.0T MRI scanner, in combination with changes in end-tidal partial pressure of CO2 (PETCO2). In each subject, we calculated the CVR amplitude and CVR response time in the gray and white matter using a step and ramp PETCO2 challenge. In addition, a separate group of 39 healthy controls who underwent the same evaluation was used to create atlases with voxel-wise mean and standard deviation of CVR amplitude and CVR response time. This allowed us to convert each metric of the 12 patients with concussion and the 12 healthy controls into z-score maps. These maps were then used to generate and compare z-scores for each of the two groups. Group differences were calculated using an unpaired t-test. Results All studies were well tolerated without any serious adverse events. Anatomical MRI was normal in all study subjects. No differences in CO2 stimulus and O2 targeting were observed between the two participant groups during BOLD MRI. With regard to the gray matter, the CVR magnitude step (P=0.117) and ramp + 10 (P=0.085) were not significantly different between patients with concussion and healthy controls. However, the tau value was significantly lower in patients with concussion than in the healthy controls (P=0.04). With regard to the white matter, the CVR magnitude step (P=0.003) and ramp + 10 (P=0.031) were significantly higher and the tau value (P=0.024) was significantly shorter in patients with concussion than in healthy controls. After z-score transformation, the z tau value was significantly lower in patients with concussion than in healthy controls (Grey matter P=0.021, White matter P=0.003). Comparison of the three parameters, z ramp + 10, z step, and z tau, between the two groups showed that z step (Grey matter P=0.035, White matter P=0.005) was the most sensitive parameter and that z ramp + 10 (Grey matter P=0.073, White matter P=0.126) was the least sensitive parameter. Conclusions Concussion is associated with patient-specific abnormalities in BOLD cerebrovascular responsiveness that occur in the setting of normal global CVR. This study demonstrates that the measurement of CVR using BOLD MRI and precise CO2 control is a safe, reliable, reproducible, and clinically useful method for evaluating the state of patients with concussion. It has the potential to be an important tool for assessing the severity and duration of symptoms after concussion.
Collapse
Affiliation(s)
- Runrun Wang
- Joint Department of Medical Imaging, University Health Network, The Toronto Western Hospital, The University of Toronto, Toronto, Ontario, Canada.,Department of Neurology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan, China.,Department of Medical Imaging, the Second Affiliated Hospital, Medical College of Shantou University, Shantou, China
| | - Julien Poublanc
- Joint Department of Medical Imaging, University Health Network, The Toronto Western Hospital, The University of Toronto, Toronto, Ontario, Canada
| | - Adrian P Crawley
- Joint Department of Medical Imaging, University Health Network, The Toronto Western Hospital, The University of Toronto, Toronto, Ontario, Canada
| | - Olivia Sobczyk
- Joint Department of Medical Imaging, University Health Network, The Toronto Western Hospital, The University of Toronto, Toronto, Ontario, Canada
| | - Sander Kneepkens
- Joint Department of Medical Imaging, University Health Network, The Toronto Western Hospital, The University of Toronto, Toronto, Ontario, Canada
| | - Larissa Mcketton
- Joint Department of Medical Imaging, University Health Network, The Toronto Western Hospital, The University of Toronto, Toronto, Ontario, Canada
| | - Charles Tator
- Department of Surgery, Division of Neurosurgery, University Health Network, The Toronto Western Hospital, The University of Toronto, Toronto, Ontario, Canada
| | - Renhua Wu
- Department of Medical Imaging, the Second Affiliated Hospital, Medical College of Shantou University, Shantou, China
| | - David J Mikulis
- Joint Department of Medical Imaging, University Health Network, The Toronto Western Hospital, The University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
7
|
Sobczyk O, Fierstra J, Venkatraghavan L, Poublanc J, Duffin J, Fisher JA, Mikulis DJ. Measuring Cerebrovascular Reactivity: Sixteen Avoidable Pitfalls. Front Physiol 2021; 12:665049. [PMID: 34305634 PMCID: PMC8294324 DOI: 10.3389/fphys.2021.665049] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 06/07/2021] [Indexed: 12/04/2022] Open
Abstract
An increase in arterial PCO2 is the most common stressor used to increase cerebral blood flow for assessing cerebral vascular reactivity (CVR). That CO2 is readily obtained, inexpensive, easy to administer, and safe to inhale belies the difficulties in extracting scientifically and clinically relevant information from the resulting flow responses. Over the past two decades, we have studied more than 2,000 individuals, most with cervical and cerebral vascular pathology using CO2 as the vasoactive agent and blood oxygen-level-dependent magnetic resonance imaging signal as the flow surrogate. The ability to deliver different forms of precise hypercapnic stimuli enabled systematic exploration of the blood flow-related signal changes. We learned the effect on CVR of particular aspects of the stimulus such as the arterial partial pressure of oxygen, the baseline PCO2, and the magnitude, rate, and pattern of its change. Similarly, we learned to interpret aspects of the flow response such as its magnitude, and the speed and direction of change. Finally, we were able to test whether the response falls into a normal range. Here, we present a review of our accumulated insight as 16 “lessons learned.” We hope many of these insights are sufficiently general to apply to a range of types of CO2-based vasoactive stimuli and perfusion metrics used for CVR.
Collapse
Affiliation(s)
- 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 Laboratory, University Health Network, Toronto, ON, Canada
| | - Jorn Fierstra
- Department of Neurosurgery, University Hospital Zurich, Zürich, Switzerland
| | - Lakshmikumar Venkatraghavan
- 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 Laboratory, University Health Network, Toronto, ON, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Joseph A Fisher
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
8
|
Al-Khazraji BK, Buch S, Kadem M, Matushewski BJ, Norozi K, Menon RS, Shoemaker JK. Protocol-dependence of middle cerebral artery dilation to modest hypercapnia. Appl Physiol Nutr Metab 2021; 46:1038-1046. [PMID: 34139129 DOI: 10.1139/apnm-2021-0220] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is a need for improved understanding of how different cerebrovascular reactivity (CVR) protocols affect vascular cross-sectional area (CSA) to reduce error in CVR calculations when measures of vascular CSA are not feasible. In human participants, we delivered ∼±4 mm Hg end-tidal partial pressure of CO2 (PETCO2) relative to baseline through controlled delivery, and measured changes in middle cerebral artery (MCA) CSA (7 Tesla magnetic resonance imaging (MRI)), blood velocity (transcranial Doppler and Phase contrast MRI), and calculated CVR based on a 3-minute steady-state (+4 mm Hg PETCO2) and a ramp (-3 to +4 mm Hg of PETCO2). We observed that (1) the MCA did not dilate during the ramp protocol (slope for CSA across time P > 0.05; R2 = 0.006), but did dilate by ∼7% during steady-state hypercapnia (P < 0.05); and (2) MCA blood velocity CVR was not different between ramp and steady-state hypercapnia protocols (ramp: 3.8 ± 1.7 vs. steady-state: 4.0 ± 1.6 cm/s/mm Hg), although calculated MCA blood flow CVR was ∼40% greater during steady-state hypercapnia than during ramp (P < 0.05) with the discrepancy due to MCA CSA changes during steady-state hypercapnia. We propose that a ramp model, across a delta of -3 to +4 mm Hg PETCO2, may provide an alternative approach to collecting CVR measures in young adults with transcranial Doppler when CSA measures are not feasible. Novelty: We optimized a magnetic resonance imaging sequence to measure dynamic middle cerebral artery (MCA) cross-sectional area (CSA). A ramp model of hypercapnia elicited similar MCA blood velocity reactivity as the steady-state model while maintaining MCA CSA.
Collapse
Affiliation(s)
- Baraa K Al-Khazraji
- Department of Kinesiology, Faculty of Science, McMaster University, Hamilton, ON, Canada
| | - Sagar Buch
- Centre for Functional and Metabolic Mapping, Robarts Research Institute, London, ON, Canada
| | - Mason Kadem
- School of Biomedical Engineering, McMaster University, Hamilton, ON, Canada
| | - Brad J Matushewski
- School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada
| | - Kambiz Norozi
- Department of Pediatrics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Department of Pediatric Cardiology, Hannover Medical School, Hannover, Germany
| | - Ravi S Menon
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Centre for Functional and Metabolic Mapping, Robarts Research Institute
| | - J Kevin Shoemaker
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,School of Kinesiology, Faculty of Health Sciences
| |
Collapse
|
9
|
Sobczyk O, Sayin ES, Sam K, Poublanc J, Duffin J, Fisher JA, Mikulis DJ. The Reproducibility of Cerebrovascular Reactivity Across MRI Scanners. Front Physiol 2021; 12:668662. [PMID: 34025455 PMCID: PMC8134667 DOI: 10.3389/fphys.2021.668662] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/12/2021] [Indexed: 11/13/2022] Open
Abstract
Cerebrovascular reactivity (CVR) is defined as the ratio of the cerebral blood flow (CBF) response to an increase in a vasoactive stimulus. We used changes in blood oxygenation level-dependent (BOLD) MRI as surrogates for changes of CBF, and standardized quantitative changes in arterial partial pressure of carbon dioxide as the stimulus. Despite uniform stimulus and test conditions, differences in voxel-wise BOLD changes between testing sites may remain, attributable to physiologic and machine variability. We generated a reference atlas of normal CVR metrics (voxel-wise mean and SD) for each of two sites. We hypothesized that there would be no significant differences in CVR between the two atlases enabling each atlas to be used at any site. A total of 69 healthy subjects were tested to create site-specific atlases, with 20 of those individuals tested at both sites. 38 subjects were scanned at Site 1 (17F, 37.5 ± 16.8 y) and 51 subjects were tested at Site 2 (22F, 40.9 ± 17.4 y). MRI platforms were: Site 1, 3T Magnetom Skyra Siemens scanner with 20-channel head and neck coil; and Site 2, 3T HDx Signa GE scanner with 8-channel head coil. To construct the atlases, test results of individual subjects were co-registered into a standard space and voxel-wise mean and SD CVR metrics were calculated. Map comparisons of z scores found no significant differences between white matter or gray matter in the 20 subjects scanned at both sites when analyzed with either atlas. We conclude that individual CVR testing, and atlas generation are compatible across sites provided that standardized respiratory stimuli and BOLD MRI scan parameters are used. This enables the use of a single atlas to score the normality of CVR metrics across multiple sites.
Collapse
Affiliation(s)
- Olivia Sobczyk
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada.,Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
| | - Ece Su Sayin
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Kevin Sam
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Joseph A Fisher
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
10
|
Fisher JA, Mikulis DJ. Cerebrovascular Reactivity: Purpose, Optimizing Methods, and Limitations to Interpretation - A Personal 20-Year Odyssey of (Re)searching. Front Physiol 2021; 12:629651. [PMID: 33868001 PMCID: PMC8047146 DOI: 10.3389/fphys.2021.629651] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 03/10/2021] [Indexed: 11/18/2022] Open
Abstract
The brain is a neurovascular organ. A stimulus-response approach is effective in interrogating the physiology of its vasculature. Ideally, the stimulus is standardized across patients, and in a single patient over time. We developed a standard stimulus and attempted to measure, classify, and interpret the many forms of responses. Over the past 20 years, our work has delivered nuanced insights into normal cerebral vascular physiology, as well as adaptive physiological responses in the presence of disease. The trajectory of our understanding did not follow a logical linear progression; rather, it emerged as a coalescence of new, old, and previously dismissed, ideas that had accumulated over time. In this essay, we review what we believe were our most valuable - and sometimes controversial insights during our two decades-long journey.
Collapse
Affiliation(s)
- Joseph A. Fisher
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - David J. Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
- The Joint Department of Medical Imaging, Toronto Western Hospital, University of Toronto, Toronto, ON, Canada
- Techna Institute & Koerner Scientist in MR Imaging, University Health Network, Toronto, ON, Canada
| |
Collapse
|
11
|
Sleight E, Stringer MS, Marshall I, Wardlaw JM, Thrippleton MJ. Cerebrovascular Reactivity Measurement Using Magnetic Resonance Imaging: A Systematic Review. Front Physiol 2021; 12:643468. [PMID: 33716793 PMCID: PMC7947694 DOI: 10.3389/fphys.2021.643468] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/01/2021] [Indexed: 12/27/2022] Open
Abstract
Cerebrovascular reactivity (CVR) magnetic resonance imaging (MRI) probes cerebral haemodynamic changes in response to a vasodilatory stimulus. CVR closely relates to the health of the vasculature and is therefore a key parameter for studying cerebrovascular diseases such as stroke, small vessel disease and dementias. MRI allows in vivo measurement of CVR but several different methods have been presented in the literature, differing in pulse sequence, hardware requirements, stimulus and image processing technique. We systematically reviewed publications measuring CVR using MRI up to June 2020, identifying 235 relevant papers. We summarised the acquisition methods, experimental parameters, hardware and CVR quantification approaches used, clinical populations investigated, and corresponding summary CVR measures. CVR was investigated in many pathologies such as steno-occlusive diseases, dementia and small vessel disease and is generally lower in patients than in healthy controls. Blood oxygen level dependent (BOLD) acquisitions with fixed inspired CO2 gas or end-tidal CO2 forcing stimulus are the most commonly used methods. General linear modelling of the MRI signal with end-tidal CO2 as the regressor is the most frequently used method to compute CVR. Our survey of CVR measurement approaches and applications will help researchers to identify good practice and provide objective information to inform the development of future consensus recommendations.
Collapse
Affiliation(s)
- Emilie Sleight
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Michael S. Stringer
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom,*Correspondence: Michael S. Stringer
| | - Ian Marshall
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Joanna M. Wardlaw
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Michael J. Thrippleton
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| |
Collapse
|
12
|
Abstract
The sensation that develops as a long breath hold continues is what this article is about. We term this sensation of an urge to breathe "air hunger." Air hunger, a primal sensation, alerts us to a failure to meet an urgent homeostatic need maintaining gas exchange. Anxiety, frustration, and fear evoked by air hunger motivate behavioral actions to address the failure. The unpleasantness and emotional consequences of air hunger make it the most debilitating component of clinical dyspnea, a symptom associated with respiratory, cardiovascular, and metabolic diseases. In most clinical populations studied, air hunger is the predominant form of dyspnea (colloquially, shortness of breath). Most experimental subjects can reliably quantify air hunger using rating scales, that is, there is a consistent relationship between stimulus and rating. Stimuli that increase air hunger include hypercapnia, hypoxia, exercise, and acidosis; tidal expansion of the lungs reduces air hunger. Thus, the defining experimental paradigm to evoke air hunger is to elevate the drive to breathe while mechanically restricting ventilation. Functional brain imaging studies have shown that air hunger activates the insular cortex (an integration center for perceptions related to homeostasis, including pain, food hunger, and thirst), as well as limbic structures involved with anxiety and fear. Although much has been learned about air hunger in the past few decades, much remains to be discovered, such as an accepted method to quantify air hunger in nonhuman animals, fundamental questions about neural mechanisms, and adequate and safe methods to mitigate air hunger in clinical situations. © 2021 American Physiological Society. Compr Physiol 11:1449-1483, 2021.
Collapse
Affiliation(s)
- Robert B Banzett
- Division of Pulmonary, Critical Care, and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Robert W Lansing
- Division of Pulmonary, Critical Care, and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Andrew P Binks
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, Virginia, USA
| |
Collapse
|
13
|
Pinto J, Bright MG, Bulte DP, Figueiredo P. Cerebrovascular Reactivity Mapping Without Gas Challenges: A Methodological Guide. Front Physiol 2021; 11:608475. [PMID: 33536935 PMCID: PMC7848198 DOI: 10.3389/fphys.2020.608475] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 12/02/2020] [Indexed: 01/08/2023] Open
Abstract
Cerebrovascular reactivity (CVR) is defined as the ability of vessels to alter their caliber in response to vasoactive factors, by means of dilating or constricting, in order to increase or decrease regional cerebral blood flow (CBF). Importantly, CVR may provide a sensitive biomarker for pathologies where vasculature is compromised. Furthermore, the spatiotemporal dynamics of CVR observed in healthy subjects, reflecting regional differences in cerebral vascular tone and response, may also be important in functional MRI studies based on neurovascular coupling mechanisms. Assessment of CVR is usually based on the use of a vasoactive stimulus combined with a CBF measurement technique. Although transcranial Doppler ultrasound has been frequently used to obtain global flow velocity measurements, MRI techniques are being increasingly employed for obtaining CBF maps. For the vasoactive stimulus, vasodilatory hypercapnia is usually induced through the manipulation of respiratory gases, including the inhalation of increased concentrations of carbon dioxide. However, most of these methods require an additional apparatus and complex setups, which not only may not be well-tolerated by some populations but are also not widely available. For these reasons, strategies based on voluntary breathing fluctuations without the need for external gas challenges have been proposed. These include the task-based methodologies of breath holding and paced deep breathing, as well as a new generation of methods based on spontaneous breathing fluctuations during resting-state. Despite the multitude of alternatives to gas challenges, existing literature lacks definitive conclusions regarding the best practices for the vasoactive modulation and associated analysis protocols. In this work, we perform an extensive review of CVR mapping techniques based on MRI and CO2 variations without gas challenges, focusing on the methodological aspects of the breathing protocols and corresponding data analysis. Finally, we outline a set of practical guidelines based on generally accepted practices and available data, extending previous reports and encouraging the wider application of CVR mapping methodologies in both clinical and academic MRI settings.
Collapse
Affiliation(s)
- Joana Pinto
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom
- Institute for Systems and Robotics - Lisboa and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Molly G. Bright
- Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
- Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL, United States
| | - Daniel P. Bulte
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom
| | - Patrícia Figueiredo
- Institute for Systems and Robotics - Lisboa and Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| |
Collapse
|
14
|
Watchmaker JM, Frederick BD, Fusco MR, Davis LT, Juttukonda MR, Lants SK, Kirshner HS, Donahue MJ. Clinical Use of Cerebrovascular Compliance Imaging to Evaluate Revascularization in Patients With Moyamoya. Neurosurgery 2020. [PMID: 29528447 DOI: 10.1093/neuros/nyx635] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Surgical revascularization is often performed in patients with moyamoya, however routine tools for efficacy evaluation are underdeveloped. The gold standard is digital subtraction angiography (DSA); however, DSA requires ionizing radiation and procedural risk, and therefore is suboptimal for routine surveillance of parenchymal health. OBJECTIVE To determine whether parenchymal vascular compliance measures, obtained noninvasively using magnetic resonance imaging (MRI), provide surrogates to revascularization success by comparing measures with DSA before and after surgical revascularization. METHODS Twenty surgical hemispheres with DSA and MRI performed before and after revascularization were evaluated. Cerebrovascular reactivity (CVR)-weighted images were acquired using hypercapnic 3-Tesla gradient echo blood oxygenation level-dependent MRI. Standard and novel analysis algorithms were applied (i) to quantify relative CVR (rCVRRAW), and decompose this response into (ii) relative maximum CVR (rCVRMAX) and (iii) a surrogate measure of the time for parenchyma to respond maximally to the stimulus, CVRDELAY. Measures between time points in patients with good and poor surgical outcomes based on DSA-visualized neoangiogenesis were contrasted (signed-rank test; significance: 2-sided P < .050). RESULTS rCVRRAW increases (P = .010) and CVRDELAY decreases (P = .001) were observed pre- vs post-revascularization in hemispheres with DSA-confirmed collateral formation; no difference was found pre- vs post-revascularization in hemispheres with poor revascularization. No significant change in rCVRMAX post-revascularization was observed in either group, or between any of the MRI measures, in the nonsurgical hemisphere. CONCLUSION Improvement in parenchymal compliance measures post-revascularization, primarily attributed to reductions in microvascular response time, is concurrent with collateral formation visualized on DSA, and may be useful for longitudinal monitoring of surgical outcomes.
Collapse
Affiliation(s)
- Jennifer M Watchmaker
- Vanderbilt University of Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Blaise deB Frederick
- Brain Imaging Center, McLean Hospital, Belmont, Massachusetts.,Consolidated Department of Psychiatry, Harvard Medical School, Boston Massachusetts
| | - Matthew R Fusco
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Larry T Davis
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Meher R Juttukonda
- Vanderbilt University of Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Sarah K Lants
- Vanderbilt University of Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Howard S Kirshner
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Manus J Donahue
- Vanderbilt University of Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Psychiatry, Vanderbilt University Medical Center, Nashville, Tennessee
| |
Collapse
|
15
|
Hoiland RL, Fisher JA, Ainslie PN. Regulation of the Cerebral Circulation by Arterial Carbon Dioxide. Compr Physiol 2019; 9:1101-1154. [DOI: 10.1002/cphy.c180021] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
16
|
McKetton L, Cohn M, Tang-Wai DF, Sobczyk O, Duffin J, Holmes KR, Poublanc J, Sam K, Crawley AP, Venkatraghavan L, Fisher JA, Mikulis DJ. Cerebrovascular Resistance in Healthy Aging and Mild Cognitive Impairment. Front Aging Neurosci 2019; 11:79. [PMID: 31031616 PMCID: PMC6474328 DOI: 10.3389/fnagi.2019.00079] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 03/19/2019] [Indexed: 12/04/2022] Open
Abstract
Measures of cerebrovascular reactivity (CVR) are used to judge the health of the brain vasculature. In this study, we report the use of several different analyses of blood oxygen dependent (BOLD) fMRI responses to CO2 to provide a number of metrics of CVR based on the sigmoidal resistance response to CO2. To assess possible differences in these metrics with age, we compiled atlases reflecting voxel-wise means and standard deviations for four different age ranges and for a group of patients with mild cognitive impairment (MCI) and compared them. Sixty-seven subjects were recruited for this study and scanned at 3T field strength. Of those, 51 healthy control volunteers between the ages of 18–83 were recruited, and 16 (MCI) subjects between the ages of 61–83 were recruited. Testing was carried out using an automated computer-controlled gas blender to induce hypercapnia in a step and ramp paradigm while monitoring end-tidal partial pressures of CO2. Surprisingly, some resistance sigmoid parameters in the oldest control group were increased compared to the youngest control group. Resistance amplitude maps showed increases in clusters within the temporal cortex, thalamus, corpus callosum and brainstem, and resistance reserve maps showed increases in clusters within the cingulate cortex, frontal gyrus, and corpus callosum. These findings suggest that some aspects of vascular reactivity in parts of the brain are initially maintained with age but then may increase in later years. We found significant reductions in all resistance sigmoid parameters (amplitude, reserve, sensitivity, midpoint, and range) when comparing MCI patients to controls. Additionally, in controls and in MCI patients, amplitude, range, reserve, and sensitivity in white matter (WM) was significantly reduced compared to gray matter (GM). WM midpoints were significantly above those of GM. Our general conclusion is that vascular regulation in terms of cerebral blood flow (CBF) responsiveness to CO2 is not significantly affected by age, but is reduced in MCI. These changes in cerebrovascular regulation demonstrate the value of resistance metrics for mapping areas of dysregulated blood flow in individuals with MCI. They may also be of value in the investigation of patients with vascular risk factors at risk for developing vascular dementia.
Collapse
Affiliation(s)
- Larissa McKetton
- Joint Department of Medical Imaging, University Health Network (UHN), Toronto, ON, Canada
| | - Melanie Cohn
- Krembil Brain Institute, University Health Network (UHN), Toronto, ON, Canada.,Department of Psychology, University of Toronto, Toronto, ON, Canada
| | - David F Tang-Wai
- Krembil Brain Institute, University Health Network (UHN), Toronto, ON, Canada.,Department of Medicine, Division of Neurology, University of Toronto and the University Health Network Memory Clinic, Toronto, ON, Canada
| | - Olivia Sobczyk
- Joint Department of Medical Imaging, University Health Network (UHN), Toronto, ON, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Kenneth R Holmes
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging, University Health Network (UHN), Toronto, ON, Canada
| | - Kevin Sam
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Adrian P Crawley
- Joint Department of Medical Imaging, University Health Network (UHN), Toronto, ON, Canada
| | - Lashmi Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network (UHN), Toronto, ON, Canada
| | - Joseph A Fisher
- Joint Department of Medical Imaging, University Health Network (UHN), Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Department of Anaesthesia and Pain Management, University Health Network (UHN), Toronto, ON, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging, University Health Network (UHN), Toronto, ON, Canada.,Krembil Brain Institute, University Health Network (UHN), Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
17
|
Cohen AD, Wang Y. Improving the Assessment of Breath-Holding Induced Cerebral Vascular Reactivity Using a Multiband Multi-echo ASL/BOLD Sequence. Sci Rep 2019; 9:5079. [PMID: 30911056 PMCID: PMC6434035 DOI: 10.1038/s41598-019-41199-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 02/28/2019] [Indexed: 01/18/2023] Open
Abstract
Breath holding (BH) is a viable vasodilatory stimulus for calculating functional MRI-derived cerebral vascular reactivity (CVR). The BH technique suffers from reduced repeatability compared with gas inhalation techniques; however, extra equipment is needed to perform gas inhalation techniques, and this equipment is not available at all institutions. This study aimed to determine the sensitivity and repeatability of BH activation and CVR using a multiband multi-echo simultaneous arterial spin labelling/blood oxygenation level dependent (ASL/BOLD) sequence. Whole-brain images were acquired in 14 volunteers. Ten subjects returned for repeat imaging. Each subject performed four cycles of 16 s BH on expiration interleaved with paced breathing. Following standard preprocessing, the echoes were combined using a T2*-weighted approach. BOLD and ASL BH activation was computed, and CVR was then determined as the percent signal change related to the activation. The "M" parameter from the Davis Model was also computed by incorporating the ASL signal. Our results showed higher BH activation strength, volume, and repeatability for the combined multi-echo (MEC) data compared with the single-echo data. MEC CVR also had higher repeatability, sensitivity, specificity, and reliability compared with the single-echo BOLD data. These data support the usefulness of an MBME ASL/BOLD acquisition for BH CVR and M measurements.
Collapse
Affiliation(s)
- Alexander D Cohen
- Medical College of Wisconsin, Department of Radiology, Milwaukee, WI, USA.
| | - Yang Wang
- Medical College of Wisconsin, Department of Radiology, Milwaukee, WI, USA.
| |
Collapse
|
18
|
Juttukonda MR, Donahue MJ. Neuroimaging of vascular reserve in patients with cerebrovascular diseases. Neuroimage 2019; 187:192-208. [PMID: 29031532 PMCID: PMC5897191 DOI: 10.1016/j.neuroimage.2017.10.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/01/2017] [Accepted: 10/07/2017] [Indexed: 12/21/2022] Open
Abstract
Cerebrovascular reactivity, defined broadly as the ability of brain parenchyma to adjust cerebral blood flow in response to altered metabolic demand or a vasoactive stimulus, is being measured with increasing frequency and may have a use for portending new or recurrent stroke risk in patients with cerebrovascular disease. The purpose of this review is to outline (i) the physiological basis of variations in cerebrovascular reactivity, (ii) available approaches for measuring cerebrovascular reactivity in research and clinical settings, and (iii) clinically-relevant cerebrovascular reactivity findings in the context of patients with cerebrovascular disease, including atherosclerotic arterial steno-occlusion, non-atherosclerotic arterial steno-occlusion, anemia, and aging. Literature references summarizing safety considerations for these procedures and future directions for standardizing protocols and post-processing procedures across centers are presented in the specific context of major unmet needs in the setting of cerebrovascular disease.
Collapse
Affiliation(s)
- Meher R Juttukonda
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Manus J Donahue
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA.
| |
Collapse
|
19
|
McKetton L, Sobczyk O, Duffin J, Poublanc J, Sam K, Crawley AP, Venkatraghavan L, Fisher JA, Mikulis DJ. The aging brain and cerebrovascular reactivity. Neuroimage 2018; 181:132-141. [DOI: 10.1016/j.neuroimage.2018.07.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 07/02/2018] [Accepted: 07/03/2018] [Indexed: 12/24/2022] Open
|
20
|
Duffin J, Sobczyk O, McKetton L, Crawley A, Poublanc J, Venkatraghavan L, Sam K, Mutch WA, Mikulis D, Fisher JA. Cerebrovascular Resistance: The Basis of Cerebrovascular Reactivity. Front Neurosci 2018; 12:409. [PMID: 29973862 PMCID: PMC6020782 DOI: 10.3389/fnins.2018.00409] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/28/2018] [Indexed: 12/20/2022] Open
Abstract
The cerebral vascular network regulates blood flow distribution by adjusting vessel diameters, and consequently resistance to flow, in response to metabolic demands (neurovascular coupling) and changes in perfusion pressure (autoregulation). Deliberate changes in carbon dioxide (CO2) partial pressure may be used to challenge this regulation and assess its performance since CO2 also acts to change vessel diameter. Cerebrovascular reactivity (CVR), the ratio of cerebral blood flow (CBF) response to CO2 stimulus is currently used as a performance metric. However, the ability of CVR to reflect the responsiveness of a particular vascular region is confounded by that region’s inclusion in the cerebral vascular network, where all regions respond to the global CO2 stimulus. Consequently, local CBF responses reflect not only changes in the local vascular resistance but also the effect of changes in local perfusion pressure resulting from redistribution of flow within the network. As a result, the CBF responses to CO2 take on various non-linear patterns that are not well-described by straight lines. We propose a method using a simple model to convert these CBF response patterns to the pattern of resistance responses that underlie them. The model, which has been used previously to explain the steal phenomenon, consists of two vascular branches in parallel fed by a major artery with a fixed resistance unchanging with CO2. One branch has a reference resistance with a sigmoidal response to CO2, representative of a voxel with a robust response. The other branch has a CBF equal to the measured CBF response to CO2 of any voxel under examination. Using the model to calculate resistance response patterns of the examined branch showed sigmoidal patterns of resistance response, regardless of the measured CBF response patterns. The sigmoid parameters of the resistance response pattern of examined voxels may be mapped to their anatomical location. We show an example for a healthy subject and for a patient with steno-occlusive disease to illustrate. We suggest that these maps provide physiological insight into the regulation of CBF distribution.
Collapse
Affiliation(s)
- James Duffin
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Olivia Sobczyk
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Larissa McKetton
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Adrian Crawley
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Lashmi Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Kevin Sam
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - W Alan Mutch
- Department of Anesthesia and Perioperative Medicine, University of Manitoba, Winnipeg, MB, Canada
| | - David Mikulis
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Joseph A Fisher
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
21
|
Chen JJ. Cerebrovascular-Reactivity Mapping Using MRI: Considerations for Alzheimer's Disease. Front Aging Neurosci 2018; 10:170. [PMID: 29922153 PMCID: PMC5996106 DOI: 10.3389/fnagi.2018.00170] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/18/2018] [Indexed: 01/14/2023] Open
Abstract
Alzheimer’s disease (AD) is associated with well-established macrostructural and cellular markers, including localized brain atrophy and deposition of amyloid. However, there is growing recognition of the link between cerebrovascular dysfunction and AD, supported by continuous experimental evidence in the animal and human literature. As a result, neuroimaging studies of AD are increasingly aiming to incorporate vascular measures, exemplified by measures of cerebrovascular reactivity (CVR). CVR is a measure that is rooted in clinical practice, and as non-invasive CVR-mapping techniques become more widely available, routine CVR mapping may open up new avenues of investigation into the development of AD. This review focuses on the use of MRI to map CVR, paying specific attention to recent developments in MRI methodology and on the emerging stimulus-free approaches to CVR mapping. It also summarizes the biological basis for the vascular contribution to AD, and provides critical perspective on the choice of CVR-mapping techniques amongst frail populations.
Collapse
Affiliation(s)
- J J Chen
- Rotman Research Institute, Baycrest, Toronto, ON, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
22
|
van Niftrik CHB, Piccirelli M, Bozinov O, Maldaner N, Strittmatter C, Pangalu A, Valavanis A, Regli L, Fierstra J. Impact of baseline CO 2 on Blood-Oxygenation-Level-Dependent MRI measurements of cerebrovascular reactivity and task-evoked signal activation. Magn Reson Imaging 2018; 49:123-130. [DOI: 10.1016/j.mri.2018.02.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/30/2018] [Accepted: 02/12/2018] [Indexed: 12/25/2022]
|
23
|
Liu P, De Vis JB, Lu H. Cerebrovascular reactivity (CVR) MRI with CO2 challenge: A technical review. Neuroimage 2018; 187:104-115. [PMID: 29574034 DOI: 10.1016/j.neuroimage.2018.03.047] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 02/06/2018] [Accepted: 03/19/2018] [Indexed: 11/16/2022] Open
Abstract
Cerebrovascular reactivity (CVR) is an indicator of cerebrovascular reserve and provides important information about vascular health in a range of brain conditions and diseases. Unlike steady-state vascular parameters, such as cerebral blood flow (CBF) and cerebral blood volume (CBV), CVR measures the ability of cerebral vessels to dilate or constrict in response to challenges or maneuvers. Therefore, CVR mapping requires a physiological challenge while monitoring the corresponding hemodynamic changes in the brain. The present review primarily focuses on methods that use CO2 inhalation as a physiological challenge while monitoring changes in hemodynamic MRI signals. CO2 inhalation has been increasingly used in CVR mapping in recent literature due to its potency in causing vasodilation, rapid onset and cessation of the effect, as well as advances in MRI-compatible gas delivery apparatus. In this review, we first discuss the physiological basis of CVR mapping using CO2 inhalation. We then review the methodological aspects of CVR mapping, including gas delivery apparatus, the timing paradigm of the breathing challenge, the MRI imaging sequence, and data analysis. In addition, we review alternative approaches for CVR mapping that do not require CO2 inhalation.
Collapse
Affiliation(s)
- Peiying Liu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, United States.
| | - Jill B De Vis
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, United States
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, United States; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, 21287, United States; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, 21205, United States
| |
Collapse
|
24
|
Mutch WAC, Ellis MJ, Ryner LN, McDonald PJ, Morissette MP, Pries P, Essig M, Mikulis DJ, Duffin J, Fisher JA. Patient-Specific Alterations in CO 2 Cerebrovascular Responsiveness in Acute and Sub-Acute Sports-Related Concussion. Front Neurol 2018; 9:23. [PMID: 29416525 PMCID: PMC5787575 DOI: 10.3389/fneur.2018.00023] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 01/11/2018] [Indexed: 01/06/2023] Open
Abstract
Background Preliminary studies suggest that sports-related concussion (SRC) is associated with alterations in cerebral blood flow (CBF) regulation. Here, we use advanced magnetic resonance imaging (MRI) techniques to measure CBF and cerebrovascular responsiveness (CVR) in individual SRC patients and healthy control subjects. Methods 15 SRC patients (mean age = 16.3, range 14–20 years) and 27 healthy control subjects (mean age = 17.6, range 13–21 years) underwent anatomical MRI, pseudo-continuous arterial spin labeling (pCASL) MRI and model-based prospective end-tidal targeting (MPET) of CO2 during blood oxygenation level-dependent (BOLD) MRI. Group differences in global mean resting CBF were examined. Voxel-by-voxel group and individual differences in regional CVR were examined using statistical parametric mapping (SPM). Leave-one-out receiver operating characteristic curve analysis was used to evaluate the utility of brain MRI CO2 stress testing biomarkers to correctly discriminate between SRC patients and healthy control subjects. Results All studies were tolerated with no complications. Traumatic structural findings were identified in one SRC patient. No significant group differences in global mean resting CBF were observed. There were no significant differences in the CO2 stimulus and O2 targeting during BOLD MRI. Significant group and patient-specific differences in CVR were observed with SRC patients demonstrating a predominant pattern of increased CVR. Leave-one-out ROC analysis for voxels demonstrating a significant increase in CVR was found to reliably discriminate between SRC patients and healthy control subjects (AUC of 0.879, p = 0.0001). The optimal cutoff for increased CVR declarative for SRC was 1,899 voxels resulting in a sensitivity of 0.867 and a specificity of 0.778 for this specific ROC analysis. There was no correlation between abnormal voxel counts and Postconcussion Symptom Scale scores among SRC patients. Conclusion Acute and subacute SRCs are associated with alterations in CVR that can be reliably detected by brain MRI CO2 stress testing in individual patients.
Collapse
Affiliation(s)
- W Alan C Mutch
- Department of Anesthesia and Perioperative Medicine, University of Manitoba, Winnipeg, MB, Canada.,University of Manitoba, Winnipeg, MB, Canada.,Canada North Concussion Network, University of Manitoba, Winnipeg, MB, Canada
| | - Michael J Ellis
- University of Manitoba, Winnipeg, MB, Canada.,Canada North Concussion Network, University of Manitoba, Winnipeg, MB, Canada.,Department of Surgery and Pediatrics and Child Health, University of Manitoba, Winnipeg, MB, Canada.,Section of Neurosurgery, University of Manitoba, Winnipeg, MB, Canada.,Pan Am Concussion Program, University of Manitoba, Winnipeg, MB, Canada.,Childrens Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada
| | - Lawrence N Ryner
- University of Manitoba, Winnipeg, MB, Canada.,Canada North Concussion Network, University of Manitoba, Winnipeg, MB, Canada.,Department of Radiology Diagnostic Imaging, University of Manitoba, Winnipeg, MB, Canada
| | - Patrick J McDonald
- Canada North Concussion Network, University of Manitoba, Winnipeg, MB, Canada.,Division of Neurosurgery, BC Children's Hospital, National Core for Neuroethics, University of British Columbia, Vancouver, BC, Canada
| | | | - Philip Pries
- Max Rady College of Medicine, University of Manitoba, Winnipeg, MB, Canada
| | - Marco Essig
- University of Manitoba, Winnipeg, MB, Canada.,Canada North Concussion Network, University of Manitoba, Winnipeg, MB, Canada.,Pan Am Concussion Program, University of Manitoba, Winnipeg, MB, Canada.,Department of Radiology Diagnostic Imaging, University of Manitoba, Winnipeg, MB, Canada
| | - David J Mikulis
- Department of Medical Imaging, University of Toronto, Toronto, ON, Canada.,University of Toronto, Toronto, ON, Canada.,University Health Network Cerebrovascular Reactivity Research Group, Toronto, ON, Canada
| | - James Duffin
- University of Toronto, Toronto, ON, Canada.,University Health Network Cerebrovascular Reactivity Research Group, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Department of Anesthesia, University of Toronto, Toronto, ON, Canada
| | - Joseph A Fisher
- University of Toronto, Toronto, ON, Canada.,University Health Network Cerebrovascular Reactivity Research Group, Toronto, ON, Canada.,Department of Anesthesia, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
25
|
Kaczmarz S, Griese V, Preibisch C, Kallmayer M, Helle M, Wustrow I, Petersen ET, Eckstein HH, Zimmer C, Sorg C, Göttler J. Increased variability of watershed areas in patients with high-grade carotid stenosis. Neuroradiology 2018; 60:311-323. [PMID: 29299616 DOI: 10.1007/s00234-017-1970-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 12/19/2017] [Indexed: 12/28/2022]
Abstract
PURPOSE Watershed areas (WSAs) of the brain are most susceptible to acute hypoperfusion due to their peripheral location between vascular territories. Additionally, chronic WSA-related vascular processes underlie cognitive decline especially in patients with cerebral hemodynamic compromise. Despite of high relevance for both clinical diagnostics and research, individual in vivo WSA definition is fairly limited to date. Thus, this study proposes a standardized segmentation approach to delineate individual WSAs by use of time-to-peak (TTP) maps and investigates spatial variability of individual WSAs. METHODS We defined individual watershed masks based on relative TTP increases in 30 healthy elderly persons and 28 patients with unilateral, high-grade carotid stenosis, being at risk for watershed-related hemodynamic impairment. Determined WSA location was confirmed by an arterial transit time atlas and individual super-selective arterial spin labeling. We compared spatial variability of WSA probability maps between groups and assessed TTP differences between hemispheres in individual and group-average watershed locations. RESULTS Patients showed significantly higher spatial variability of WSAs than healthy controls. Perfusion on the side of the stenosis was delayed within individual watershed masks as compared to a watershed template derived from controls, being independent from the grade of the stenosis and collateralization status of the circle of Willis. CONCLUSION Results demonstrate feasibility of individual WSA delineation by TTP maps in healthy elderly and carotid stenosis patients. Data indicate necessity of individual segmentation approaches especially in patients with hemodynamic compromise to detect critical regions of impaired hemodynamics.
Collapse
Affiliation(s)
- Stephan Kaczmarz
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany
- TUM Neuroimaging Center (TUM-NIC), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Vanessa Griese
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany
- TUM Neuroimaging Center (TUM-NIC), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Christine Preibisch
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany
- Clinic for Neurology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Michael Kallmayer
- Department of Vascular and Endovascular Surgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Michael Helle
- Research Laboratories, Philips GmbH Innovative Technologies, Hamburg, Germany
| | - Isabel Wustrow
- I. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Esben Thade Petersen
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Copenhagen, Denmark
- Center for Magnetic Resonance, Department of Electrical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Hans-Henning Eckstein
- Department of Vascular and Endovascular Surgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Claus Zimmer
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany
| | - Christian Sorg
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany
- TUM Neuroimaging Center (TUM-NIC), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Jens Göttler
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany.
- TUM Neuroimaging Center (TUM-NIC), Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
| |
Collapse
|
26
|
Duffin J, Sobczyk O, Crawley A, Poublanc J, Venkatraghavan L, Sam K, Mutch A, Mikulis D, Fisher J. The role of vascular resistance in BOLD responses to progressive hypercapnia. Hum Brain Mapp 2017; 38:5590-5602. [PMID: 28782872 DOI: 10.1002/hbm.23751] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 07/20/2017] [Accepted: 07/20/2017] [Indexed: 12/22/2022] Open
Abstract
The ability of the cerebral vasculature to regulate vascular diameter, hence resistance and cerebral blood flow (CBF), in response to metabolic demands (neurovascular coupling), and perfusion pressure changes (autoregulation) may be assessed by measuring the CBF response to carbon dioxide (CO2 ). In healthy individuals, the CBF response to a ramp CO2 stimulus from hypocapnia to hypercapnia is assumed sigmoidal or linear. However, other response patterns commonly occur, especially in individuals with cerebrovascular disease, and these remain unexplained. CBF responses to CO2 in a vascular region are determined by the combined effects of the innate vascular responses to CO2 and the local perfusion pressure; the latter ensuing from pressure-flow interactions within the cerebral vascular network. We modeled this situation as two vascular beds perfused in parallel from a fixed resistance source. Our premise is that all vascular beds have a sigmoidal reduction of resistance in response to a progressive rise in CO2 . Surrogate CBF data to test the model was provided by magnetic resonance imaging of blood oxygen level-dependent (BOLD) signals. The model successfully generated all the various BOLD-CO2 response patterns, providing a physiological explanation of CBF distribution as relative differences in the network of vascular bed resistance responses to CO2 . Hum Brain Mapp 38:5590-5602, 2017. © 2017 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- James Duffin
- Department of Physiology, University Health Network, Toronto, Canada.,Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, Canada
| | - Olivia Sobczyk
- Institute of Medical Science, University of Toronto, Toronto, Canada
| | - Adrian Crawley
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, Canada
| | - Lashmi Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, Canada
| | - Kevin Sam
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, Canada
| | - Alan Mutch
- Department of Anesthesia and Perioperative Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - David Mikulis
- Institute of Medical Science, University of Toronto, Toronto, Canada.,Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, Canada
| | - Joseph Fisher
- Department of Physiology, University Health Network, Toronto, Canada.,Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, Canada.,Institute of Medical Science, University of Toronto, Toronto, Canada
| |
Collapse
|