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MR flow measurement using RF phase gradients in receiver coil arrays
N Famili1, S M Wright, J R Porter
1Department of Electrical Engineering, Texas A&M University, College Station 77843.
IEEE Transactions on Bio-Medical Engineering
|December 1, 1993
Summary
This study introduces a novel method to extract blood flow velocity information from magnetic resonance (MR) images. By using multiple receiver coils, researchers can accurately measure flow in major vessels without additional scan time.
Area of Science:
- Medical Imaging
- Biophysics
- Cardiovascular Research
Background:
- Radio frequency (RF) phase gradients in receiver coils can encode flow velocity in magnetic resonance (MR) images.
- These flow-encoded phase variations are often obscured by larger phase shifts from B0 inhomogeneities and susceptibility variations.
- Existing methods may require additional scan time or specialized sequences for flow quantification.
Purpose of the Study:
- To develop a method for retrospectively extracting flow velocity information from standard MR imaging sequences.
- To overcome limitations of phase variations caused by static magnetic field inhomogeneities.
- To enable accurate, non-invasive blood flow measurements in major vasculature.
Main Methods:
- Utilizing RF phase gradients within receiver coil patterns to encode velocity.
- Employing arrays of independent receiver coils and a multi-channel receiver.
- Subtracting simultaneously acquired images from different coils to isolate flow-induced phase variations.
- Retrospective analysis applicable to standard and flow-compensated MR sequences.
Main Results:
- Demonstrated successful recovery of flow velocity information from MR images.
- Achieved sufficient sensitivity for measuring velocities in vessels like the carotid arteries.
- Showed that the method is compatible with standard imaging protocols, requiring no extra scan time.
- Indicated that using more receiver coils enhances accuracy and expands measurement capabilities.
Conclusions:
- A novel technique allows for accurate retrospective quantification of blood flow velocity using MR imaging.
- The multi-coil subtraction method effectively isolates flow information, overcoming confounding phase variations.
- This approach offers a time-efficient and sensitive tool for cardiovascular flow assessment.