Department of Telecommunication and Control Engineering, School of Engineering, University of Sao Paulo, Sao Paulo, Brazil.
Ultrasound Med Biol. 2012 Aug;38(8):1414-28. doi: 10.1016/j.ultrasmedbio.2012.03.014. Epub 2012 Jun 12.
Ultrasonography has an inherent noise pattern, called speckle, which is known to hamper object recognition for both humans and computers. Speckle noise is produced by the mutual interference of a set of scattered wavefronts. Depending on the phase of the wavefronts, the interference may be constructive or destructive, which results in brighter or darker pixels, respectively. We propose a filter that minimizes noise fluctuation while simultaneously preserving local gray level information. It is based on steps to attenuate the destructive and constructive interference present in ultrasound images. This filter, called interference-based speckle filter followed by anisotropic diffusion (ISFAD), was developed to remove speckle texture from B-mode ultrasound images, while preserving the edges and the gray level of the region. The ISFAD performance was compared with 10 other filters. The evaluation was based on their application to images simulated by Field II (developed by Jensen et al.) and the proposed filter presented the greatest structural similarity, 0.95. Functional improvement of the segmentation task was also measured, comparing rates of true positive, false positive and accuracy. Using three different segmentation techniques, ISFAD also presented the best accuracy rate (greater than 90% for structures with well-defined borders).
超声成像具有固有噪声模式，称为散斑，这会干扰人类和计算机对物体的识别。散斑噪声是由一组散射波前的相互干扰产生的。根据波前的相位，干扰可能是建设性的或破坏性的，从而分别导致更亮或更暗的像素。我们提出了一种滤波器，它可以在最小化噪声波动的同时保持局部灰度信息。它基于衰减超声图像中存在的破坏性和建设性干扰的步骤。这种滤波器称为基于干扰的散斑滤波器加各向异性扩散（ISFAD），用于从 B 模式超声图像中去除散斑纹理，同时保留边缘和区域的灰度级。将 ISFAD 的性能与其他 10 种滤波器进行了比较。评估基于它们在 Field II（由 Jensen 等人开发）模拟图像上的应用，该滤波器的结构相似度最高，为 0.95。还通过比较真阳性、假阳性和准确率来衡量分割任务的功能改进。使用三种不同的分割技术，ISFAD 还呈现出最高的准确率（对于具有明确定义边界的结构，准确率大于 90%）。
