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Updated: Jun 30, 2026
Non-invasive Optical Measurement of Cerebral Metabolism and Hemodynamics in Infants
Published on: March 14, 2013
Cerebral blood flow measurement using fMRI and PET: a cross-validation study
Jean J Chen1, Marguerite Wieckowska, Ernst Meyer
1McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, PQ, Canada H3A 2B4. jean.chen@mail.mcgill.ca
Abstract:
An important aspect of functional magnetic resonance imaging (fMRI) is the study of brain hemodynamics, and MR arterial spin labeling (ASL) perfusion imaging has gained wide acceptance as a robust and noninvasive technique. However, the cerebral blood flow (CBF) measurements obtained with ASL fMRI have not been fully validated, particularly during global CBF modulations. We present a comparison of cerebral blood flow changes (DeltaCBF) measured using a flow-sensitive alternating inversion recovery (FAIR) ASL perfusion method to those obtained using H(2) (15)O PET, which is the current gold standard for in vivo imaging of CBF. To study regional and global CBF changes, a group of 10 healthy volunteers were imaged under identical experimental conditions during presentation of 5 levels of visual stimulation and one level of hypercapnia. The CBF changes were compared using 3 types of region-of-interest (ROI) masks. FAIR measurements of CBF changes were found to be slightly lower than those measured with PET (average DeltaCBF of 21.5 +/- 8.2% for FAIR versus 28.2 +/- 12.8% for PET at maximum stimulation intensity). Nonetheless, there was a strong correlation between measurements of the two modalities. Finally, a t-test comparison of the slopes of the linear fits of PET versus ASL DeltaCBF for all 3 ROI types indicated no significant difference from unity (P > .05).
Insights
MR arterial spin labeling (ASL) accurately measures cerebral blood flow (CBF) changes, correlating well with the gold standard H(2)(15)O PET. This validates ASL fMRI for studying brain hemodynamics.
Area of Science:
- Neuroimaging
- Physiology
- Medical Physics
Background:
- Functional magnetic resonance imaging (fMRI) is crucial for studying brain hemodynamics.
- MR arterial spin labeling (ASL) is a noninvasive perfusion imaging technique for measuring cerebral blood flow (CBF).
- Validation of ASL CBF measurements, especially during global modulations, is essential.
Purpose of the Study:
- To compare cerebral blood flow changes (DeltaCBF) measured by flow-sensitive alternating inversion recovery (FAIR) ASL with H(2)(15)O Positron Emission Tomography (PET).
- To validate ASL fMRI as a reliable method for quantifying CBF changes in vivo.
Main Methods:
- Ten healthy volunteers underwent imaging using FAIR ASL and H(2)(15)O PET under identical conditions.
- Experimental conditions included five levels of visual stimulation and one level of hypercapnia to induce global CBF changes.
- Comparisons were made using three region-of-interest (ROI) masks.
Main Results:
- FAIR ASL measurements of DeltaCBF were slightly lower than PET measurements (21.5% vs. 28.2% at maximum stimulation).
- A strong correlation was observed between DeltaCBF measurements from FAIR ASL and H(2)(15)O PET.
- Statistical analysis showed no significant difference between the slopes of linear fits comparing the two modalities across ROIs.
Conclusions:
- FAIR ASL provides a validated and reliable method for assessing cerebral blood flow changes.
- ASL fMRI is a robust tool for in vivo hemodynamic studies, comparable to H(2)(15)O PET.
- The findings support the use of ASL in functional neuroimaging research.
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