Limits...
Cerebral blood flow measurement using fMRI and PET: a cross-validation study.

Chen JJ, Wieckowska M, Meyer E, Pike GB - Int J Biomed Imaging (2008)

Bottom Line: 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).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).

View Article: PubMed Central - PubMed

Affiliation: McConnell 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).

No MeSH data available.


Related in: MedlinePlus

BOLD (a) and FAIR (b) time coursesof the CBF percent change in the V1 ROI averaged over 10 subjects are shown,from left to right, corresponding to baseline, 25%, 50%, 75%, and 100%intensity checkerboards and 5% hypercapnia. The horizontal bars represent the3-minute periods during which the stimulus was on. An increase in signal changecan be observed with increasing checkerboard intensity for BOLD and FAIRperfusion, ranging between 1.0%–1.9% and 11.4%–22.5%, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2553188&req=5

fig4: BOLD (a) and FAIR (b) time coursesof the CBF percent change in the V1 ROI averaged over 10 subjects are shown,from left to right, corresponding to baseline, 25%, 50%, 75%, and 100%intensity checkerboards and 5% hypercapnia. The horizontal bars represent the3-minute periods during which the stimulus was on. An increase in signal changecan be observed with increasing checkerboard intensity for BOLD and FAIRperfusion, ranging between 1.0%–1.9% and 11.4%–22.5%, respectively.

Mentions: Time-seriesCBF data were obtained only from fMRI data as PET measurements were notavailable as separate frames. The BOLD and FAIR time courses were obtained byaveraging all voxels in the ROI and shown in Figure 4 in the V1 ROI of onesubject (activation paradigm from left to right: baseline, checkerboards from25% to 100% intensity and hypercapnia). We observed an increase in the level ofsignal change with increasing checkerboard intensity for both BOLD and FAIR. Asexpected, the activation SNR, defined as the ratio of the ROI mean over thestandard deviation during activation, was lower for FAIR than for BOLD.


Cerebral blood flow measurement using fMRI and PET: a cross-validation study.

Chen JJ, Wieckowska M, Meyer E, Pike GB - Int J Biomed Imaging (2008)

BOLD (a) and FAIR (b) time coursesof the CBF percent change in the V1 ROI averaged over 10 subjects are shown,from left to right, corresponding to baseline, 25%, 50%, 75%, and 100%intensity checkerboards and 5% hypercapnia. The horizontal bars represent the3-minute periods during which the stimulus was on. An increase in signal changecan be observed with increasing checkerboard intensity for BOLD and FAIRperfusion, ranging between 1.0%–1.9% and 11.4%–22.5%, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2553188&req=5

fig4: BOLD (a) and FAIR (b) time coursesof the CBF percent change in the V1 ROI averaged over 10 subjects are shown,from left to right, corresponding to baseline, 25%, 50%, 75%, and 100%intensity checkerboards and 5% hypercapnia. The horizontal bars represent the3-minute periods during which the stimulus was on. An increase in signal changecan be observed with increasing checkerboard intensity for BOLD and FAIRperfusion, ranging between 1.0%–1.9% and 11.4%–22.5%, respectively.
Mentions: Time-seriesCBF data were obtained only from fMRI data as PET measurements were notavailable as separate frames. The BOLD and FAIR time courses were obtained byaveraging all voxels in the ROI and shown in Figure 4 in the V1 ROI of onesubject (activation paradigm from left to right: baseline, checkerboards from25% to 100% intensity and hypercapnia). We observed an increase in the level ofsignal change with increasing checkerboard intensity for both BOLD and FAIR. Asexpected, the activation SNR, defined as the ratio of the ROI mean over thestandard deviation during activation, was lower for FAIR than for BOLD.

Bottom Line: 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).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).

View Article: PubMed Central - PubMed

Affiliation: McConnell 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).

No MeSH data available.


Related in: MedlinePlus