IEEE Trans Ultrason Ferroelectr Freq Control. 2017 Jun;64(6):910-921. doi: 10.1109/TUFFC.2017.2683559. Epub 2017 Mar 16.
During a transcostal ultrasound scan, ribs and other highly attenuating and/or reflective tissue structures can block parts of the array. Blocked elements tend to limit the acoustic window and impede visualization of structures of interest. Here, we demonstrate a method to detect blocked elements and we measure the loss of image quality they introduce in simulation and in vivo. We utilize a fullwave simulation tool and a clinical ultrasound scanner to obtain element signals from fully sampled matrix arrays during simulated and in vivo transcostal liver scans, respectively. The elements that were blocked by a rib showed lower average signal amplitude and lower average nearest-neighbor cross correlation than the elements in the remainder of the 2-D aperture. The growing receive-aperture B-mode images created from the element data indicate that the signals on blocked elements are dominated by noise and that turning them OFF has a potential to improve visibility of liver vasculature. Adding blocked elements to the growing receive apertures for five in vivo transcostal acquisitions resulted in average decrease in vessel contrast and contrast to noise ratio of 19% and 10%, respectively.
在经胸廓超声扫描中，肋骨和其他高衰减和/或高反射组织结构可能会阻挡部分探头阵元。被阻挡的阵元会限制声窗，阻碍对感兴趣结构的可视化。在这里，我们展示了一种检测被阻挡阵元的方法，并在模拟和体内测量了它们对图像质量的损失。我们利用全波模拟工具和临床超声扫描仪，分别从模拟和体内经胸廓肝脏扫描的完全采样矩阵探头中获取阵元信号。被肋骨阻挡的阵元的平均信号幅度和平均最近邻互相关系数均低于二维孔径其余部分的阵元。从阵元数据生成的扩展接收孔径 B 模式图像表明，被阻挡阵元的信号主要是噪声，将它们关闭可能有助于提高肝脏血管的可视性。在 5 次体内经胸廓采集过程中，向扩展接收孔径添加被阻挡阵元，导致血管对比度和对比噪声比平均分别下降 19%和 10%。
