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Magnetization transfer enhanced vascular-space-occupancy (MT-VASO) functional MRI
Jun Hua1, Manus J Donahue, Jason M Zhao
1The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Magnetic Resonance in Medicine
|February 14, 2009
Summary
Magnetization transfer (MT) prepulses enhance signal-to-noise ratio (SNR) in vascular-space-occupancy (VASO) MRI. This novel MT-VASO technique improves contrast-to-noise ratio (CNR) for better blood volume detection.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Biomedical Engineering
- Neuroimaging
Background:
- Vascular-space-occupancy (VASO) MRI detects blood volume changes using blood signal nulling.
- VASO MRI suffers from low signal-to-noise ratio (SNR) due to minimal remaining tissue signal during blood nulling.
Purpose of the Study:
- To investigate the use of magnetization transfer (MT) prepulses to enhance SNR in VASO MRI.
- To assess the impact of MT prepulses on blood nulling time and functional MRI (fMRI) performance.
Main Methods:
- MT prepulses were applied before or after inversion to modulate tissue magnetization.
- MT effects on blood were measured ex vivo and in vivo to determine compatibility with VASO nulling times.
- Functional MRI experiments using MT-VASO were conducted in the human visual cortex at 3 Tesla.
Main Results:
- MT effects on blood were minimal (<2.5%) under specific parameters, allowing for consistent nulling times.
- MT-VASO demonstrated comparable relative signal changes to VASO.
- Contrast-to-noise ratio (CNR) was significantly enhanced in MT-VASO compared to VASO (44-44% increase).
Conclusions:
- MT prepulses effectively increase SNR in VASO MRI without compromising blood nulling.
- MT-VASO offers improved CNR, enhancing the sensitivity of blood volume measurements in fMRI.
- This technique holds promise for improving the diagnostic capabilities of VASO imaging.
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