A single-ensemble-based hybrid approach to clutter rejection combining bilinear Hankel with regression.
OBJECTIVE
Clutter regarded as ultrasound Doppler echoes of soft tissue interferes with the primary objective of color flow imaging (CFI): measurement and display of blood flow. Multi-ensemble samples based clutter filters degrade resolution or frame rate of CFI. The prevalent single-ensemble clutter rejection filter is based on a single rejection criterion and fails to achieve a high accuracy for estimating both the low- and high-velocity blood flow components.


METHODS
The Bilinear Hankel-SVD achieved more exact signal decomposition than the conventional Hankel-SVD. Furthermore, the correlation between two arbitrary eigen-components obtained by the B-Hankel-SVD was demonstrated. In the hybrid approach, the input ultrasound Doppler signal first passes through a low-order regression filter, and then the output is properly decomposed into a collection of eigen-components under the framework of B-Hankel-SVD. The blood flow components are finally extracted based on a frequency threshold.


RESULTS
In a series of simulations, the proposed B-Hankel-SVD filter reduced the estimation bias of the blood flow over the conventional Hankel-SVD filter. The hybrid algorithm was shown to be more effective than regression or Hankel-SVD filters alone in rejecting the undesirable clutter components with single-ensemble (S-E) samples. It achieved a significant improvement in blood flow frequency estimation and estimation variance over the other competing filters.
Department of Control Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China. shenzyhit@gmail.com.|School of Electric and Computer Engineering, Georgia Institute of Technology, Atlanta, 30332, USA. shenzyhit@gmail.com.
Zhiyuan
Z
Shen
Department of Control Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China.
Naizhang
N
Feng
School of Electric and Computer Engineering, Georgia Institute of Technology, Atlanta, 30332, USA.
Chin-Hui
CH
Lee
Bilinear model; Clutter rejection; Hankel; Hybrid; Polynomial regression