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Fast echo-shifted gradient-recalled MRI: combining a short repetition time with variable T2* weighting
1In Vivo NMR Research Center, BEIP, NCRR, National Institutes of Health, Bethesda, MD 20892.
Magnetic Resonance in Medicine
|July 1, 1993
Summary
This study enhances T2*-weighted magnetic resonance imaging (MRI) for greater sensitivity. New echo-shifting techniques allow flexible T2*-weighting without increasing scan time, improving contrast agent tracking.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Biomedical Engineering
- Neuroimaging
Background:
- Fast T2*-weighted MRI methods are crucial for detecting susceptibility effects.
- Existing methods have limitations in T2* sensitivity and flexibility.
- Susceptibility contrast agents are valuable for studying blood volume and flow.
Purpose of the Study:
- To extend existing fast T2*-weighted MRI principles for enhanced sensitivity.
- To introduce a flexible echo-shifting technique for adjustable T2*-weighting.
- To demonstrate the application of these techniques for tracking contrast agents in vivo.
Main Methods:
- Extension of the echo-shifting concept by lengthening T2*-weighting periods using gradient schemes.
- Application of coherence pathway formalism to analyze echo selection and coherence attenuation.
- Demonstration in cat brain imaging with a susceptibility contrast agent.
Main Results:
- Achieved progressively delayed gradient-recalled echoes without RF refocusing.
- Demonstrated increased flexibility in T2*-weighting without altering total imaging time.
- Successfully generated relative blood-volume maps with clear white and gray matter contrast.
Conclusions:
- The developed MRI technique significantly enhances T2* sensitivity and flexibility.
- Echo-shifting offers a powerful tool for optimizing T2*-weighting in MRI.
- This method is effective for in vivo tracking of susceptibility contrast agents and deriving quantitative blood-volume information.