Synopsis

Keywords: Cardiovascular: Hemodynamics, Neuro: Cerebrovascular, Neuro: Neurodegeneration

Cerebrovascular reactivity (CVR) denotes the ability of cerebral vessels to dilate or constrict in response to challenges or maneuvers. This physiological parameter is an important index of the brain’s vascular health, and provides vascular reserve information that is complementary to steady-state vascular parameters, such as cerebral blood flow (CBF) and cerebral blood volume (CBV). This presentation will introduce MRI methods for CVR mapping. It will review the methodological aspects of CVR mapping techniques, as well as their application in cerebrovascular and neurodegenerative diseases.

Cerebrovascular reactivity (CVR) denotes the ability of cerebral vessels to dilate or constrict in response to challenges or maneuvers. This physiological parameter is thought to be an important index of the brain’s vascular health, and provides vascular reserve information that is complementary to steady-state vascular parameters, such as cerebral blood flow (CBF) and cerebral blood volume (CBV).

In recent years, there has been a surging interest in the measurement of CVR in a range of applications. This presentation aims to provide a review of the technical aspects of CVR mapping using MRI and its clinical applications. CVR mapping is different from other perfusion imaging techniques in that a physiological challenge is usually required during the MRI scan. We will first introduce MRI methods that use CO2 inhalation as a physiological challenge while monitoring changes in hemodynamic MRI signals. CO2 inhalation has been increasingly used in recent literature due to its potency in causing vasodilation, rapid onset and cessation of the effect, as well as recent advances in MRI-compatible gas delivery apparatus.. Specifically, we will discuss the physiological basis of CVR mapping using CO2 inhalation, and also the methodological aspects of CVR mapping, including gas delivery apparatus, the timing paradigm of the breathing challenge, the MRI imaging sequence, and data analysis. Next, we will introduce alternative MRI approaches for CVR mapping that do not use CO2 inhalation, such as the use of breath holding, acetazolamide injection, and the newly developed resting-state CVR mapping. Examples of the clinical applications of these CVR mapping techniques in cerebrovascular and neurodegenerative diseases will also be provided.

Acknowledgements

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References

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