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Arterial spin labeling perfusion fMRI with very low task frequency.
Jiongjiong Wang1, Geoffrey K Aguirre, Daniel Y Kimberg
1Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA. jwang@rad.upenn.edu
Magnetic Resonance in Medicine
|April 22, 2003
Summary
Arterial spin labeling (ASL) perfusion imaging offers superior sensitivity for detecting brain activation over long periods compared to blood oxygenation level-dependent (BOLD) contrast. ASL is ideal for low-frequency brain function studies and longitudinal research.
Area of Science:
- Neuroimaging
- Functional Magnetic Resonance Imaging (fMRI)
Background:
- Blood oxygenation level-dependent (BOLD) contrast is widely used in fMRI but suffers from poor sensitivity to slow neural activity due to baseline drift.
- Arterial spin labeling (ASL) perfusion contrast minimizes drift effects, showing stable noise characteristics suitable for low-frequency brain function analysis.
Purpose of the Study:
- To compare the sensitivity of ASL and BOLD contrast in detecting motor cortex activation across a range of experimental frequencies.
- To evaluate ASL's suitability for detecting slow and longitudinal changes in brain activity.
Main Methods:
- Investigated the relative sensitivities of ASL and BOLD contrast.
- Varied the alternating period between resting state and activation from 30 seconds to 24 hours.
- Measured motor cortex activation.
Main Results:
- ASL detected motor cortex activation over minutes, hours, and days.
- ASL sensitivity surpassed BOLD for activation periods longer than a few minutes.
- ASL measurements exhibited less intersubject variability than BOLD.
Conclusions:
- ASL contrast enhances sensitivity for low-frequency and longitudinal fMRI studies.
- ASL's improved performance and reduced variability are expected to broaden the scope of fMRI experimental designs.
- ASL offers superior power for group analysis in fMRI research.