scholarly journals Feasibility and safety of intraoperative BOLD functional MRI cerebrovascular reactivity to evaluate extracranial-to-intracranial bypass efficacy

2019 ◽  
Vol 46 (2) ◽  
pp. E7 ◽  
Author(s):  
Giovanni Muscas ◽  
Christiaan Hendrik Bas van Niftrik ◽  
Jorn Fierstra ◽  
Marco Piccirelli ◽  
Martina Sebök ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Functional Mri ◽  
Bypass Graft ◽  
Tissue Level ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Bypass Flow ◽  
Hemodynamic Changes ◽  
Flow Measurements ◽  
Oxygenation Level

Blood oxygenation level–dependent functional MRI cerebrovascular reactivity (BOLD-CVR) is a contemporary technique to assess brain tissue hemodynamic changes after extracranial- intracranial (EC-IC) bypass flow augmentation surgery. The authors conducted a preliminary study to investigate the feasibility and safety of intraoperative 3-T MRI BOLD-CVR after EC-IC bypass flow augmentation surgery. Five consecutive patients selected for EC-IC bypass revascularization underwent an intraoperative BOLD-CVR examination to assess early hemodynamic changes after revascularization and to confirm the safety of this technique. All patients had a normal postoperative course, and none of the patients exhibited complications or radiological alterations related to prolonged anesthesia time. In addition to intraoperative flow measurements of the bypass graft, BOLD-CVR maps added information on the hemodynamic status and changes at the brain tissue level. Intraoperative BOLD-CVR is feasible and safe in patients undergoing EC-IC bypass revascularization. This technique can offer immediate hemodynamic feedback on brain tissue revascularization after bypass flow augmentation surgery.

Abstract 167: Noninvasive MRI Measurement of Cerebrovascular Reactivity Enables Evaluation of Surgical Revascularization Response in Moyamoya

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Travis R Ladner ◽  
Carlos Faraco ◽  
Manus J Donahue ◽  
Daniel Arteaga ◽  
Lori C Jordan ◽  
...  
Keyword(s):  
Tissue Level ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Clinical Severity ◽  
Atmospheric Air ◽  
Bold Mri ◽  
Oxygenation Level ◽  
Hemodynamic Improvement ◽  
Mri Changes ◽  
Mri Measurements

Introduction: Frequent dissociation between clinical severity and angiographic grading of moyamoya supports a role for alternative tissue-level hemodynamic measures. Here, angiography is complemented with noninvasive MRI measurements of parenchymal impairment to assess changes in cerebrovascular reactivity (CVR) after extracranial-intracranial bypass in moyamoya. Hypothesis: CVR is regionally impaired pre-operatively, yet increases after surgery. This can be visualized noninvasively by assessing blood oxygenation level-dependent (BOLD) MRI changes with safe, mildly hypercarbic gas. Methods: Using a block MRI paradigm, carbogen (5% CO 2 ; 95% O 2 3 min) was interleaved with atmospheric air (<1% CO 2 ; 3 min) administration during BOLD MRI in intracranial stenosis patients (n=70), a subset of which (n=9; age=35.7+/-10.8; 7F/2M) underwent indirect (n=8) or direct (n=1) revascularization for moyamoya. Five patients had both pre-operative and post-operative hemodynamic imaging, with post-operative scans performed after 7.3+/-4.1 months. CVR, calculated as a z-statistic in response to hypercarbia vs. atmospheric air, was compared (two-tailed t-test) for each patient between the two time points to correlate CVR changes with surgery. Results: Fig. 1 shows BOLD MRI on a patient scanned before and 2 years after right-sided indirect bypass, with significant (t=79.29, p<0.01) right-sided hemodynamic improvement. Cohort analyses of patients with pre/post-operative scans revealed significant interhemispheric CVR differences prior to surgery (t=3.48, p<0.01), which resolved after bypass (t=0.88, p=0.20). Additionally, CVR increased significantly in the operative hemisphere (t=4.50, p<0.01). Conclusions: CVR-weighted hemodynamic MRI can be implemented into routine clinical protocols, corresponds well with revascularization response, and has potential as a noninvasive complement to angiography for serial monitoring of moyamoya patients.

scholarly journals The Role of Cerebrovascular-Reactivity Mapping in Functional MRI: Calibrated fMRI and Resting-State fMRI

2021 ◽  
Vol 12 ◽  
Author(s):  
J. Jean Chen ◽  
Claudine J. Gauthier
Keyword(s):  
Functional Mri ◽  
Resting State ◽  
Resting State Fmri ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Resting State Functional Connectivity ◽  
Non Invasive ◽  
Oxygenation Level ◽  
Calibrated Fmri

Task and resting-state functional MRI (fMRI) is primarily based on the same blood-oxygenation level-dependent (BOLD) phenomenon that MRI-based cerebrovascular reactivity (CVR) mapping has most commonly relied upon. This technique is finding an ever-increasing role in neuroscience and clinical research as well as treatment planning. The estimation of CVR has unique applications in and associations with fMRI. In particular, CVR estimation is part of a family of techniques called calibrated BOLD fMRI, the purpose of which is to allow the mapping of cerebral oxidative metabolism (CMRO2) using a combination of BOLD and cerebral-blood flow (CBF) measurements. Moreover, CVR has recently been shown to be a major source of vascular bias in computing resting-state functional connectivity, in much the same way that it is used to neutralize the vascular contribution in calibrated fMRI. Furthermore, due to the obvious challenges in estimating CVR using gas challenges, a rapidly growing field of study is the estimation of CVR without any form of challenge, including the use of resting-state fMRI for that purpose. This review addresses all of these aspects in which CVR interacts with fMRI and the role of CVR in calibrated fMRI, provides an overview of the physiological biases and assumptions underlying hypercapnia-based CVR and calibrated fMRI, and provides a view into the future of non-invasive CVR measurement.

scholarly journals Hemodynamic and metabolic changes during hypercapnia with normoxia and hyperoxia using pCASL and TRUST MRI in healthy adults

2021 ◽  
pp. 0271678X2110645
Author(s):  
Pieter T Deckers ◽  
Alex A Bhogal ◽  
Mathijs BJ Dijsselhof ◽  
Carlos C Faraco ◽  
Peiying Liu ◽  
...  
Keyword(s):  
Arterial Spin Labeling ◽  
Oxygen Metabolism ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Oxygen Extraction Fraction ◽  
Mixed Effect ◽  
Cerebral Oxygen Metabolism ◽  
Extraction Fraction ◽  
Oxygenation Level

Blood oxygenation level-dependent (BOLD) or arterial spin labeling (ASL) MRI with hypercapnic stimuli allow for measuring cerebrovascular reactivity (CVR). Hypercapnic stimuli are also employed in calibrated BOLD functional MRI for quantifying neuronally-evoked changes in cerebral oxygen metabolism (CMRO2). It is often assumed that hypercapnic stimuli (with or without hyperoxia) are iso-metabolic; increasing arterial CO2 or O2 does not affect CMRO2. We evaluated the null hypothesis that two common hypercapnic stimuli, ‘CO2 in air’ and carbogen, are iso-metabolic. TRUST and ASL MRI were used to measure the cerebral venous oxygenation and cerebral blood flow (CBF), from which the oxygen extraction fraction (OEF) and CMRO2 were calculated for room-air, ‘CO2 in air’ and carbogen. As expected, CBF significantly increased (9.9% ± 9.3% and 12.1% ± 8.8% for ‘CO2 in air’ and carbogen, respectively). CMRO2 decreased for ‘CO2 in air’ (−13.4% ± 13.0%, p < 0.01) compared to room-air, while the CMRO2 during carbogen did not significantly change. Our findings indicate that ‘CO2 in air’ is not iso-metabolic, while carbogen appears to elicit a mixed effect; the CMRO2 reduction during hypercapnia is mitigated when including hyperoxia. These findings can be important for interpreting measurements using hypercapnic or hypercapnic-hyperoxic (carbogen) stimuli.

scholarly journals Hemodynamic investigation of peritumoral impaired blood oxygenation-level dependent cerebrovascular reactivity in patients with diffuse glioma

2020 ◽  
Vol 70 ◽  
pp. 50-56
Author(s):  
Giovanni Muscas ◽  
Christiaan Hendrik Bas van Niftrik ◽  
Martina Sebök ◽  
Katharina Seystahl ◽  
Marco Piccirelli ◽  
...  
Keyword(s):  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Diffuse Glioma ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

scholarly journals The Cumulative Influence of Hyperoxia and Hypercapnia on Blood Oxygenation and R2*

2015 ◽  
Vol 35 (12) ◽  
pp. 2032-2042 ◽  
Author(s):  
Carlos C Faraco ◽  
Megan K Strother ◽  
Jeroen CW Siero ◽  
Daniel F Arteaga ◽  
Allison O Scott ◽  
...  
Keyword(s):  
Venous Blood ◽  
Quantitative Information ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Resonance Imaging ◽  
Tissue Water ◽  
Bold Mri ◽  
Bold Imaging ◽  
Complex Interactions ◽  
Oxygenation Level

Cerebrovascular reactivity (CVR)-weighted blood-oxygenation-level-dependent magnetic resonance imaging (BOLD-MRI) experiments are frequently used in conjunction with hyperoxia. Owing to complex interactions between hyperoxia and hypercapnia, quantitative effects of these gas mixtures on BOLD responses, blood and tissue R2∗, and blood oxygenation are incompletely understood. Here we performed BOLD imaging (3T; TE/TR = 35/2,000 ms; spatial resolution = 3×3×3.5 mm3) in healthy volunteers ( n = 12; age = 29±4.1 years) breathing (i) room air (RA), (ii) normocapnic-hyperoxia (95% O2/5% N2, HO), (iii) hypercapnic-normoxia (5% CO2/21% O2/74% N2, HC-NO), and (iv) hypercapnic-hyperoxia (5% CO2/95% O2, HC-HO). For HC-HO, experiments were performed with separate RA and HO baselines to control for changes in O2. T2-relaxation-under-spin-tagging MRI was used to calculate basal venous oxygenation. Signal changes were quantified and established hemodynamic models were applied to quantify vasoactive blood oxygenation, blood–water R∗2, and tissue-water R∗2. In the cortex, fractional BOLD changes (stimulus/baseline) were HO/RA = 0.011 ± 0.007; HC-NO/RA = 0.014±0.004; HC-HO/HO = 0.020±0.008; and HC-HO/RA = 0.035 ±0.010; for the measured basal venous oxygenation level of 0.632, this led to venous blood oxygenation levels of 0.660 (HO), 0.665 (HC-NO), and 0.712 (HC-HO). Interleaving a HC-HO stimulus with HO baseline provided a smaller but significantly elevated BOLD response compared with a HC-NO stimulus. Results provide an outline for how blood oxygenation differs for several gas stimuli and provides quantitative information on how hypercapnic BOLD CVR and R∗2 are altered during hyperoxia.

Sex Differences in Blood-Oxygenation-Level-Dependent Functional MRI With Primary Visual Stimulation

1998 ◽  
Vol 155 (3) ◽  
pp. 434-436 ◽  
Author(s):  
Jonathan M. Levin ◽  
Marjorie H. Ross ◽  
Jack H. Mendelson ◽  
Nancy K. Mello ◽  
Bruce M. Cohen ◽  
...  
Keyword(s):  
Sex Differences ◽  
Functional Mri ◽  
Visual Stimulation ◽  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Blood Oxygenation Level ◽  
Oxygenation Level

scholarly journals The Vascular Steal Phenomenon is an Incomplete Contributor to Negative Cerebrovascular Reactivity in Patients with Symptomatic Intracranial Stenosis

2014 ◽  
Vol 34 (9) ◽  
pp. 1453-1462 ◽  
Author(s):  
Daniel F Arteaga ◽  
Megan K Strother ◽  
Carlos C Faraco ◽  
Lori C Jordan ◽  
Travis R Ladner ◽  
...  
Keyword(s):  
Clinical Symptoms ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Intracranial Stenosis ◽  
Compensatory Mechanism ◽  
Ischemic Cerebrovascular Disease ◽  
Oxygenation Level ◽  
Fluid Attenuated Inversion Recovery ◽  
Vascular Steal ◽  
Negative Bold

‘Vascular steal’ has been proposed as a compensatory mechanism in hemodynamically compromised ischemic parenchyma. Here, independent measures of cerebral blood flow (CBF) and blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) responses to a vascular stimulus in patients with ischemic cerebrovascular disease are recorded. Symptomatic intracranial stenosis patients ( n = 40) underwent a multimodal 3.0T MRI protocol including structural (T1-weighted and T2-weighted fluid-attenuated inversion recovery) and hemodynamic (BOLD and CBF-weighted arterial spin labeling) functional MRI during room air and hypercarbic gas administration. CBF changes in regions demonstrating negative BOLD reactivity were recorded, as well as clinical correlates including symptomatic hemisphere by infarct and lateralizing symptoms. Fifteen out of forty participants exhibited negative BOLD reactivity. Of these, a positive relationship was found between BOLD and CBF reactivity in unaffected (stenosis degree <50%) cortex. In negative BOLD cerebrovascular reactivity regions, three patients exhibited significant ( P < 0.01) reductions in CBF consistent with vascular steal; six exhibited increases in CBF; and the remaining exhibited no statistical change in CBF. Secondary findings were that negative BOLD reactivity correlated with symptomatic hemisphere by lateralizing clinical symptoms and prior infarcts(s). These data support the conclusion that negative hypercarbia-induced BOLD responses, frequently assigned to vascular steal, are heterogeneous in origin with possible contributions from autoregulation and/or metabolism.

Impact of baseline CO 2 on Blood-Oxygenation-Level-Dependent MRI measurements of cerebrovascular reactivity and task-evoked signal activation

2018 ◽  
Vol 49 ◽  
pp. 123-130 ◽  
Author(s):  
Christiaan Hendrik Bas van Niftrik ◽  
Marco Piccirelli ◽  
Oliver Bozinov ◽  
Nicolai Maldaner ◽  
Catherine Strittmatter ◽  
...  
Keyword(s):  
Blood Oxygenation Level Dependent ◽  
Blood Oxygenation ◽  
Cerebrovascular Reactivity ◽  
Blood Oxygenation Level ◽  
Oxygenation Level ◽  
Mri Measurements ◽  
Signal Activation ◽  
And Task
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