Absolute CBF and CBV measurements by MRI bolus tracking before and after acetazolamide challenge: repeatabilily and comparison with PET in humans
Related Experiment Video
Updated: Aug 17, 2026
A Dual Tracer PET-MRI Protocol for the Quantitative Measure of Regional Brain Energy Substrates Uptake in the Rat
Published on: December 28, 2013
Cécile B Grandin1, Anne Bol, Anne M Smith
1Department of Radiology, St Luc University Hospital, Université Catholique de Louvain, Brussels, Belgium. grandin@rdgn.ucl.ac.be
Abstract:
Bolus tracking magnetic resonance imaging (MRI) is a powerful technique for assessing cerebral perfusion, but its capability to measure absolute cerebral blood flow (CBF) and volume (CBV) values is still debated. To validate the MRI technique, absolute CBF and CBV values in healthy humans obtained by echo planar gradient echo MRI were compared to H(2)(15)O and (11)CO positron emission tomography (PET) before and after acetazolamide (ACZ) (n = 8) or saline (n = 4) administration. The repeatability of CBF and CBV measurements was moderate with both methods, and slightly lower with MRI than with PET. At rest, the mean CBF values were similar with both techniques except in the cortex where they were moderately higher with MRI. CBV was higher with MRI than with PET in all areas, which may reflect an underestimation of the arterial input function (AIF). After ACZ, a significant CBF increase was observed in gray matter with both MRI and PET, suggesting that MRI might be used to assess the cerebrovascular reserve. In individual subjects, the correlation between MRI and PET measurements was good for both CBF and CBV (R(2) between 0.70 and 0.84). However, when all results were considered as a group, R(2) was lower (0.40 to 0.65), and the limits of agreement between the two methods (SD of the difference) were large. Our data suggest that physiologic CBF values and systematically overestimated CBV values may be obtained with MRI in healthy humans, but that an individual scale factor should be applied to MRI measurements to improve the agreement with PET.
Insights
Bolus tracking MRI offers moderate accuracy for cerebral blood flow (CBF) and volume (CBV) in healthy humans. Adjusting MRI values with a scale factor may improve agreement with PET imaging for better clinical use.
Area of Science:
- Neuroimaging
- Medical Physics
- Radiology
Background:
- Bolus tracking MRI is used for cerebral perfusion assessment.
- Its accuracy in measuring absolute cerebral blood flow (CBF) and cerebral blood volume (CBV) is debated.
- Validation against positron emission tomography (PET) is needed.
Purpose of the Study:
- To validate echo planar gradient echo MRI for absolute CBF and CBV measurements.
- To compare MRI-derived values with H(2)(15)O and (11)CO PET in healthy humans.
- To assess MRI's utility in evaluating cerebrovascular reserve.
Main Methods:
- Comparison of MRI and PET measurements of CBF and CBV in 12 healthy subjects.
- Measurements were taken at rest and after acetazolamide or saline administration.
- Repeatability and agreement between MRI and PET were analyzed.
Main Results:
- Moderate repeatability for both MRI and PET, slightly lower for MRI.
- Similar mean CBF values between MRI and PET, except in the cortex (higher with MRI).
- CBV was consistently higher with MRI, potentially due to arterial input function underestimation.
- MRI and PET showed significant CBF increase after acetazolamide, indicating potential for cerebrovascular reserve assessment.
- Good individual subject correlation (R(2) 0.70-0.84) but lower group correlation (R(2) 0.40-0.65) with large agreement limits.
Conclusions:
- MRI may provide physiologic CBF values but systematically overestimates CBV in healthy humans.
- An individual scale factor applied to MRI measurements could improve agreement with PET.
- MRI shows potential for assessing cerebrovascular reserve, but calibration is necessary.
