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Perfusion imaging by un-inverted flow-sensitive alternating inversion recovery (UNFAIR)
J A Helpern1, C A Branch, M N Yongbi
1Center for Advanced Brain Imaging, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY USA. helpern@nki.rfmh.org
Magnetic Resonance Imaging
|January 1, 1997
Summary
A novel UNFAIR pulse sequence accurately measures cerebral blood flow (CBF) using alternating spin inversion. This method visualizes CBF changes in rat brains, offering a new tool for neuroscience research.
Area of Science:
- Neuroimaging
- Magnetic Resonance Imaging (MRI)
- Cerebrovascular Physiology
Background:
- Accurate estimation of cerebral blood flow (CBF) is crucial for understanding brain function and disease.
- Existing inversion recovery techniques have limitations in precisely quantifying CBF.
- Developing advanced MRI pulse sequences is essential for improved diagnostic and research capabilities.
Purpose of the Study:
- Introduce and validate a new MRI pulse sequence, UNFAIR (Unbalanced FAIR), for estimating cerebral blood flow.
- To demonstrate the efficacy of UNFAIR in capturing physiological changes in CBF.
- To provide a theoretical model for the UNFAIR sequence and compare it with experimental data.
Main Methods:
- The UNFAIR pulse sequence utilizes sequential hyperbolic secant preparatory pulses.
- It employs a unique approach where spins in the target slice maintain +z magnetization while in-flowing spins are alternately inverted and uninverted.
- CBF-weighted images were acquired from rat brains under normocapnia and hypercapnia.
Main Results:
- The UNFAIR sequence successfully generated CBF-weighted images of rat brains.
- Observed CBF changes under normocapnia and hypercapnia conditions were consistent with physiological expectations.
- A model was developed to describe the signal response, showing good agreement with in-vivo data from gray and white matter.
Conclusions:
- The UNFAIR pulse sequence is a viable and effective method for estimating cerebral blood flow.
- This technique demonstrates sensitivity to physiological changes in CBF.
- The UNFAIR sequence and its accompanying model offer a promising advancement for quantitative CBF MRI in research and potentially clinical settings.