Research Materials Supporting the Publication Entitled "Cerebrovascular Reactivity Measurements Using Simultaneous 15O-Water PET and ASL MRI: Impacts of Arterial Transit Time, Labeling Efficiency, and Hematocrit"
- Cerebrovascular reactivity (CVR) reflects the capacity of the brain to meet changing physiological demands and can predict the risk of cerebrovascular diseases. CVR can be obtained by measuring the change in cerebral blood flow (CBF) during a brain stress test where CBF is altered by a vasodilator such as acetazolamide. Although the gold standard to quantify CBF is PET imaging, the procedure is invasive and inaccessible to most patients. Arterial spin labeling (ASL) is a non-invasive and quantitative MRI method to measure CBF, and a consensus guideline has been published for the clinical application of ASL. Despite single post labeling delay (PLD) pseudo-continuous ASL (PCASL) being the recommended ASL technique for CBF quantification, it is sensitive to variations to the arterial transit time (ATT) and labeling efficiency induced by the vasodilator in CVR studies. Multi-PLD ASL controls for the changes in ATT, and velocity selective ASL is in theory insensitive to both ATT and labeling efficiency. Here we investigate CVR using simultaneous 15O-water PET and ASL MRI data from 19 healthy subjects. CVR and CBF measured by the ASL techniques were compared using PET as the reference technique. The impacts of blood T1 and labeling efficiency on ASL were assessed using individual measurements of hematocrit and flow velocity data of the carotid and vertebral arteries measured using phase-contrast MRI. We found that multi-PLD PCASL is the ASL technique most consistent with PET for CVR quantification (group mean CVR of the whole brain = 42±19% and 40±18% respectively). Single-PLD ASL underestimated the CVR of the whole brain significantly by 15±10% compared with PET (p<0.01, paired t test). Changes in ATT pre- and post-acetazolamide was the principal factor affecting ASL-based CVR quantification. Variations in labeling efficiency and blood T1 had negligible effects.
|Type of resource
|September 8, 2022
|September 2, 2022
|Research team head
|Stanford University. Department of Radiology
|Stanford University. School of Medicine
|cerebral blood flow
|positron emission tomography
|Magnetic resonance imaging
|pseudo-continuous arterial spin labeling
|velocity selective arterial spin labeling
- Use and reproduction
- User agrees that, where applicable, content will not be used to identify or to otherwise infringe the privacy or confidentiality rights of individuals. Content distributed via the Stanford Digital Repository may be subject to additional license and use restrictions applied by the depositor.
- This work is licensed under a Creative Commons Attribution Non Commercial 4.0 International license (CC BY-NC).
- Preferred citation
- Zhao, Moss Y and Zaharchuk, Greg. (2021). Research Materials Supporting the Publication Entitled "Cerebrovascular Reactivity Measurements Using Simultaneous 15O-Water PET and ASL MRI: Impacts of Arterial Transit Time, Labeling Efficiency, and Hematocrit". Stanford Digital Repository. Available at: https://purl.stanford.edu/jm289gm4861 https://doi.org/10.25740/jm289gm4861
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