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Blood Flow Imaging with Ultrafast Doppler
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Design strategies for improved velocity-selective pulse sequences.

Gerald B Matson1

  • 1Department of Veterans Affairs Medical Center, San Francisco, CA 94121, United States; Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, United States.

Magnetic Resonance Imaging
|September 12, 2017
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Summary
This summary is machine-generated.

New magnetic resonance imaging (MRI) methods improve blood flow visualization without contrast agents. These enhanced sequences offer sharper transitions and better stability for accurate flow measurement.

Keywords:
Blood flowVelocity-selective inversionVelocity-selective saturation

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Area of Science:

  • Medical Imaging
  • Biophysics
  • Magnetic Resonance Imaging

Background:

  • Contrast-agent-free MRI methods visualize blood flow using flow-encoding gradients.
  • Existing methods have limitations including poor transition sharpness, long scan times, and susceptibility to magnetic field variations.

Purpose of the Study:

  • To develop improved radiofrequency (RF) pulse sequences for blood flow MRI.
  • Enhance immunity to radiofrequency inhomogeneity and resonance offsets.
  • Minimize sequence length while maintaining flow sensitivity.

Main Methods:

  • Design modifications for existing long RF pulse sequences.
  • Utilized Bloch equations simulations to test sequence performance.
  • Evaluated sequences in the presence of blood flow and magnetic field imperfections.

Main Results:

  • Developed new sequences with improved immunity to RF inhomogeneity and resonance offsets.
  • Achieved sharp transitions between stationary and flowing spins.
  • Demonstrated sequences suitable for 3.0 Tesla MRI systems.

Conclusions:

  • The proposed design methods enhance the performance of blood flow MRI sequences.
  • These improvements allow for more accurate and robust blood flow quantification.
  • The optimized sequences are practical for clinical application at 3.0T.