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Rapid quantitation of high-speed flow jets
Krishna S Nayak1, Bob S Hu, Dwight G Nishimura
1Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA. nayak@mrsrl.stanford.edu
Magnetic Resonance in Medicine
|July 24, 2003
Summary
This study introduces a novel prospectively gated spiral phase contrast MRI technique for accurately measuring high-velocity blood flow in patients with heart conditions. The method significantly reduces artifacts, enabling faster, more precise imaging within a single breathhold.
Area of Science:
- Cardiovascular MRI
- Flow Imaging
- Medical Imaging Physics
Background:
- High-velocity blood flow (5-7 m/s) in congenital heart defects and valvular disease necessitates accurate quantitation.
- Conventional 2D Fast Fourier Transform (2DFT) phase contrast MRI (PC-MRI) sequences are time-consuming (minutes).
- Conventional spiral PC-MRI is faster but prone to severe artifacts at high velocities due to phase dispersion.
Purpose of the Study:
- To develop and validate a novel prospectively gated spiral PC-MRI technique for rapid, artifact-free high-velocity flow imaging.
- To achieve high spatial and temporal resolution for accurate clinical assessment of cardiovascular flow dynamics.
Main Methods:
- A new prospectively gated spiral phase contrast sequence with a short measurement interval (<4 ms) was implemented.
- High spatial resolution (2 x 2 x 4 mm³) and temporal resolution (22 ms) were achieved.
- Acquisition was performed within a single breathhold (10 heartbeats) for a single slice movie loop.
Main Results:
- Simulations demonstrated the technique's capability to image jets up to 10 m/s.
- In vivo studies in aortic stenosis patients showed accurate peak velocity measurements up to 4.2 m/s.
- Measurements were validated against echocardiography, showing good agreement.
Conclusions:
- The prospectively gated spiral PC-MRI technique effectively minimizes flow artifacts in high-velocity jets.
- This method enables rapid, accurate, and artifact-reduced quantification of cardiovascular blood flow.
- It offers a clinically viable solution for assessing patients with valvular heart disease and congenital defects.