| 1. |
- Mozumi, Michiya, et al.
(author)
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Anti-Aliasing method for ultrasonic 2D phase-sensitive motion estimator
- 2020
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In: Japanese Journal of Applied Physics. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 59:SK
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Journal article (peer-reviewed)abstract
- A 2D motion estimator can estimate tissue motions and blood flow dynamics more accurately than a 1D motion estimator. In this study, we proposed a simple anti-Aliasing filter to unwrap the phase of the cross spectrum. The proposed method is evaluated by simulation mimicking steady flows, and the magnitude of the true velocity was changed from 200 to 2400 mm s-1. In the simulation, bias error was improved from 295.0% to 4.9% by the proposed method at a true velocity magnitude of 1600 mm s-1. Also, in the in vivo measurement of the left ventricle, the wrapping in the phase of the cross spectrum was corrected by the proposed method, and the directions of the blood velocity vectors were estimated more accurately.
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| 2. |
- Mozumi, Michiya, et al.
(author)
-
Impact of spacing of ultrasound receiving beams on estimation of 2D motion velocity
- 2021
-
In: Japanese Journal of Applied Physics. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 60:SD
-
Journal article (peer-reviewed)abstract
- For more detailed measurement of cardiovascular motion and complex blood flow, a two-dimensional (2D) velocity estimation method is required in functional ultrasound imaging. The block matching method based on the correlation function is one of the standard 2D motion estimators. In this study, we investigated the effect of lateral sampling intervals of an ultrasonic B-mode image on the accuracy in velocity estimation. In simulation, bias error (BE) in estimated velocities became -13% with an ultrasonic center frequency of 7.5 MHz and spacings of receiving beams of 0.2 mm. Such a BE was improved from -13% to -1.4% by changing the spacings from 0.2 to 0.1 mm. In the in vivo experiment, the maximum velocity obtained with spacings of 0.2 mm was underestimated by -16% as compared to those obtained with 0.1 mm. Hence, the trend was similar to that in the simulation.
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| 3. |
- Nagaoka, Ryo, et al.
(author)
-
Basic study on estimation method of wall shear stress in common carotid artery using blood flow imaging
- 2020
-
In: Japanese Journal of Applied Physics. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 59
-
Journal article (peer-reviewed)abstract
- In this paper, we propose a method for adaptive selection of the kernel size used in estimation of the wall shear stress (WSS) based on flow velocity profiles obtained by the blood flow imaging method based on enhancement of RF echo signals from blood cells using a singular value decomposition based clutter filter. Two simulation phantom experiments with the Field II program were performed to validate the proposed method. In the simulation experiments, the average bias error (BE) between the WSSs estimated by the conventional method and theoretical one was 16.5%. The proposed method could reduce the average BE to 12.3%. Also, the proposed method was applied to RF echo signals from a common carotid artery (CCA) of a healthy male subject. The WSSs in the CCA were estimated during one cardiac cycle and in a range similar to that in previous reports.
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