Cerebrovascular Reactivity Measurement Using Magnetic Resonance Imaging: A Systematic Review

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.

A Comparison of CVR Magnitude and Delay Assessed at 1.5 and 3T in Patients With Cerebral Small Vessel Disease

“…Lastly further methodological work is required to assess comparability and encourage greater consensus on best practice. Although the reported CVR magnitude and delay values are comparable to previously reported values ( Thrippleton et al, 2018 ), wider comparisons are challenging due to heterogeneity in the acquisition and processing methods ( Sleight et al, 2021 ). Additionally, we have not explored reproducibility of CVR measurements using fixed CO 2 inhalation at 3T although we previously tested reproducibility and different durations of CO 2 exposure at 1.5T ( Thrippleton et al, 2018 ).…”

Assessment of microvascular rarefaction in human brain disorders using physiological magnetic resonance imaging

“… 119 Note that CVR can also be measured using other MRI techniques, for instance based on the blood-oxygen-level-dependent (BOLD) effect, which were reviewed elsewehere. 124 …”

“…119 Note that CVR can also be measured using other MRI techniques, for instance based on the bloodoxygen-level-dependent (BOLD) effect, which were reviewed elsewehere. 124 Previous ASL studies in healthy aging and AD have critically been reviewed, whereby it was concluded that ASL is a promising tool to measure hypoperfusion in AD, contributing to early AD diagnosis. 125 The hypoperfusion patterns found with ASL resembled fluorodeoxyglucose positron emission tomography (FDG-PET) derived hypometabolism patterns in AD and mild cognitive impairment.…”

Cerebral Vasoreactivity Changes Over Time in Patients With Different Clinical Manifestations of Cerebral Small Vessel Disease

“…There are no biological markers to accurately assess brain vasoreactivity; however, CVR can be evaluated by various tools, such as single photon emission computed tomography (SPECT), PET, various MRI techniques, and transcranial Doppler ultrasound (TCD) (Terborg et al, 2000). Currently, one of the most widely used methods to measure the CVR is MRI, and it offers advantages over the use of radiolabeled products while maintaining regional specificity (Sleight et al, 2021). Though no direct anatomical information can be obtained, TCD permits for the evaluation of mean flow velocity (MFV) changes in the major cerebral arteries after a vasodilative stimulus and it provides complementary information of the brain hemodynamics (Ringelstein et al, 1988;Ebrahim et al, 2019;Burley et al, 2021a).…”