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Interpretation of flow encoding and quantification in MRI: time domain versus frequency domain
F Peeters1, R Luypaert, H Eisendrath
1Biomedical MR Unit, Academic Hospital AZ-VUB, Brussels, Belgium.
Magnetic Resonance in Medicine
|November 1, 1996
Summary
This study presents a time-domain analysis of magnetic resonance imaging (MRI) flow encoding using impulse response, interpreting flow encoding as a weighted averaging process. This method clarifies relationships with frequency-domain and gradient moment expansion approaches for improved flow quantification.
Area of Science:
- Medical Imaging
- Physics
- Biomedical Engineering
Background:
- Traditional MRI flow analysis relies on gradient moment expansion.
- Linear response theory offers an alternative frequency-domain approach using transfer functions.
- Understanding flow encoding is crucial for accurate MRI.
Purpose of the Study:
- To analyze flow encoding and quantification in the time domain using impulse response.
- To clarify the relationship between time-domain, frequency-domain, and gradient moment expansion approaches.
- To explore novel applications of time-domain flow analysis in MRI.
Main Methods:
- Analysis of flow encoding and quantification in the time domain.
- Utilizing impulse response functions to model flow effects.
- Comparing time-domain results with frequency-domain and gradient moment expansion methods.
Main Results:
- Flow encoding is characterized as a weighted averaging process.
- Instantaneous flow encoding is linked to the centroid of the impulse response.
- Clarified the physical meaning of the encoding instant and its relation to other methods.
Conclusions:
- The time-domain analysis provides a new perspective on MRI flow encoding.
- Applications include minimizing misregistration with asymmetrical gradients and flow quantification with oscillating gradients.
- Combining time and frequency domain analyses is expected to yield new MRI applications.