Title :
Minimum variance beamforming combined with adaptive coherence weighting applied to medical ultrasound imaging
Author :
Asl, Babak Mohammadzadeh ; Mahloojifar, Ali
Author_Institution :
Dept. of Biomed. Eng., Tarbiat Modares Univ., Tehran, Iran
fDate :
9/1/2009 12:00:00 AM
Abstract :
Currently, the nonadaptive delay-and-sum (DAS) beamformer is used in medical ultrasound imaging. However, due to its data-independent nature, DAS leads to images with limited resolution and contrast. In this paper, an adaptive minimum variance (MV)-based beamformer that combines the MV and coherence factor (CF) weighting is introduced and adapted to medical ultrasound imaging. MV-adaptive beamformers can improve the image quality in terms of resolution and sidelobes by suppressing off-axis signals, while keeping onaxis ones. In addition, CF weighting can improve contrast and sidelobes by emphasizing the in-phase signals and reducing the out-of-phase ones. Combining MV and CF weighting results in simultaneous improvement of imaging resolution and contrast, outperforming both DAS and MV beamformers. In addition, because of the power of CF in reducing the focusing errors, the proposed method presents satisfactory robustness against sound velocity inhomogeneities, outperforming the regularized MV beamformer. The excellent performance of the proposed beamforming approach is demonstrated by several simulated examples.
Keywords :
array signal processing; biomedical ultrasonics; coherence; ultrasonic imaging; adaptive coherence weighting; coherence factor; delay-and-sum beamformer; imaging contrast improvement; imaging resolution improvement; medical ultrasound imaging; minimum variance beamforming; sound velocity inhomogeneities; Array signal processing; Biomedical imaging; Delay; Focusing; Image quality; Image resolution; Robustness; Signal resolution; Ultrasonic imaging; Algorithms; Computer Simulation; Image Processing, Computer-Assisted; Phantoms, Imaging; Signal Processing, Computer-Assisted; Ultrasonography;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2009.1268