| Autor: |
Vaitkus PJ; Defense and Civil Inst. of Environ. Med., Toronto, Ont., Cobbold RC |
| Jazyk: |
angličtina |
| Zdroj: |
IEEE transactions on ultrasonics, ferroelectrics, and frequency control [IEEE Trans Ultrason Ferroelectr Freq Control] 1998; Vol. 45 (4), pp. 939-54. |
| DOI: |
10.1109/58.710565 |
| Abstrakt: |
A significant improvement in blood velocity estimation accuracy can be achieved by simultaneously processing both temporal and spatial information obtained from a sample volume. Use of the spatial information becomes especially important when the temporal resolution is limited. By using a two-dimensional sequence of spatially sampled Doppler signal "snapshots" an improved estimate of the Doppler correlation matrix can be formed. Processing Doppler data in this fashion addresses the range-velocity spread nature of the distributed red blood cell target, leading to a significant reduction in spectral speckle. Principal component spectral analysis of the "snapshot" correlation matrix is shown to lead to a new and robust Doppler mode frequency estimator. By processing only the dominant subspace of the Doppler correlation matrix, the Cramer-Rao bounds on the estimation error of target velocity is significantly reduced in comparison to traditional narrowband blood velocity estimation methods and achieves almost the same local accuracy as a wideband estimator. A time-domain solution is given for the velocity estimate using the root-MUSIC algorithm, which makes the new estimator attractive for real-time implementation. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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