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Perfusion imaging by a flow-sensitive alternating inversion recovery (FAIR) technique: application to functional
1Department of Radiology, University of Minnesota Medical School, Minneapolis 55455, USA.
Magnetic Resonance in Medicine
|March 1, 1997
Summary
The novel flow-sensitive alternating inversion recovery (FAIR) technique accurately measures cerebral blood flow (CBF). FAIR imaging offers advantages over BOLD in detecting brain activation, suggesting complete coupling of oxygen consumption and CBF changes.
Area of Science:
- Neuroimaging
- Physiology
- Medical Physics
Background:
- Perfusion is vital for tissue function, necessitating accurate measurement of cerebral blood flow (CBF).
- Existing functional magnetic resonance imaging (fMRI) techniques have limitations in fully characterizing perfusion dynamics.
Purpose of the Study:
- To evaluate a new flow-sensitive alternating inversion recovery (FAIR) technique for measuring CBF.
- To compare the sensitivity of FAIR imaging with the Blood Oxygen Level-Dependent (BOLD) technique in detecting brain activation.
Main Methods:
- Utilized FAIR imaging to assess the dependency of signal intensity on inversion times (TI).
- Acquired simultaneous FAIR and BOLD images during unilateral finger opposition tasks.
- Measured gray matter CBF and activation-induced CBF changes in the motor cortex.
Main Results:
- FAIR signal distribution varied with TI, with longer TIs showing diffusion into gray matter.
- Normal gray matter CBF was determined to be 71 ± 15 ml/100 g/min.
- FAIR detected activation in some areas not identified by BOLD, indicating complete coupling of oxygen consumption and CBF.
Conclusions:
- FAIR is a valuable technique for quantifying CBF and offers enhanced sensitivity for detecting brain activation compared to BOLD.
- FAIR imaging can differentiate micro- and macrovessel contributions by adjusting TI.
- Findings suggest that oxygen consumption increases are fully coupled with CBF changes during functional activation.