IEEE Trans Ultrason Ferroelectr Freq Control. 2012 Apr;59(4):817-24. doi: 10.1109/TUFFC.2012.2260.
In freehand elastography, quasi-static tissue compression is applied through the ultrasound probe, and the corresponding axial strain is estimated by calculating the time shift between consecutive echo signals. This calculation typically suffers from a poor signal-to-noise ratio or from the decorrelation between consecutive echoes resulting from an erroneous axial motion impressed by the operator. This paper shows that the quality of elastograms can be improved through the integration of two distinct techniques in the strain estimation procedure. The first technique evaluates the displacement of the tissue by analyzing the phases of the echo signal spectra acquired during compression. The second technique increases the displacement estimation robustness by averaging multiple displacement estimations in a high-frame-rate imaging system, while maintaining the typical elastogram frame-rate. The experimental results, obtained with the Ultrasound Advanced Open Platform (ULA-OP) and a cyst phantom, demonstrate that each of the proposed methods can independently improve the quality of elastograms, and that further improvements are possible through their combination.
在自由式弹性成像中，通过超声探头施加准静态组织压缩，通过计算连续回波信号之间的时移来估计相应的轴向应变。这种计算通常受到信噪比差的影响，或者由于操作员施加的轴向运动错误导致连续回波之间的去相关。本文表明，通过在应变估计过程中集成两种不同的技术，可以提高弹性图像的质量。第一种技术通过分析压缩过程中获取的回波信号频谱的相位来评估组织的位移。第二种技术通过在高帧率成像系统中平均多次位移估计来提高位移估计的稳健性，同时保持典型的弹性图像帧率。使用超声高级开放式平台（ULA-OP）和囊肿模型获得的实验结果表明，所提出的每种方法都可以独立地提高弹性图像的质量，并且通过它们的组合可以实现进一步的改进。
