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Real-time Fourier velocity encoding: an in vivo evaluation
Christopher K Macgowan1, Christian J Kellenberger, Jay S Detsky
1Department of Medical Imaging, University of Toronto and Hospital for Sick Children, Toronto, Canada. chris.macgowan@utoronto.ca
Journal of Magnetic Resonance Imaging : JMRI
|February 22, 2005
Summary
Real-time Fourier velocity encoding (FVE) magnetic resonance imaging (MRI) shows strong agreement with spectral-Doppler ultrasound for blood flow velocity measurements. This advanced MRI technique offers potential for hemodynamic assessment in challenging vascular applications.
Area of Science:
- Medical Imaging
- Cardiovascular Physiology
- Biomedical Engineering
Background:
- Accurate in vivo blood flow velocity measurement is crucial for diagnosing and monitoring cardiovascular conditions.
- Traditional methods like spectral-Doppler ultrasound and phase-contrast (PC) magnetic resonance (MR) imaging have limitations in certain clinical scenarios.
- Developing novel, real-time imaging techniques is essential for expanding hemodynamic assessment capabilities.
Purpose of the Study:
- To compare the accuracy and reliability of in vivo real-time Fourier velocity encoding (FVE) magnetic resonance (MR) imaging against spectral-Doppler ultrasound and gated PC MR imaging.
- To evaluate the qualitative and quantitative agreement of blood flow velocity measurements obtained by these different imaging modalities.
Main Methods:
- Velocity spectra were measured in the aorta and inferior vena cava of eight healthy volunteers using in vivo real-time FVE MR imaging.
- Measurements were compared qualitatively (flow pattern appearance) and quantitatively (peak velocity) with spectral-Doppler ultrasound and gated PC MR imaging.
- In vitro validation was performed to assess the agreement between FVE and PC MR imaging peak velocities.
Main Results:
- Excellent agreement (R² = 0.99) was observed between in vitro FVE and PC MR imaging for peak velocity measurements.
- In vivo, FVE and ultrasound showed close qualitative agreement in most cases (21/24), while PC MR resolved fewer velocity peaks due to temporal averaging (13/24 agreement with FVE).
- Quantitative analysis revealed strong correlations between FVE and ultrasound (R² = 0.71) and between FVE and PC MR (R² = 0.85) for peak velocity.
Conclusions:
- Real-time FVE MR imaging provides reliable assessment of blood flow velocity, correlating well with spectral-Doppler ultrasound.
- This advanced MR technique may enable hemodynamic assessment in vessels not accessible to ultrasound.
- FVE MR imaging could be particularly valuable for patients unable to undergo respiratory compensation during imaging.