In vivo ultrasound attenuation coefficient measurements are of interest as they can provide insight into tissue pathology. They are also needed so that measurements of the tissue's frequency dependent ultrasound backscattering coefficient may be corrected for attenuation. In vivo measurements of the attenuation coefficient are challenging because it has to be estimated from the depth dependent decay of backscatter signals that display a large degree of magnitude variation. In this study we describe and evaluate an improved backscatter method to estimate ultrasound attenuation which is tolerant to the presence of some backscatter inhomogeneity. This employs an automated algorithm to segment and remove atypically strong echoes to lessen the potential bias these may introduce on the attenuation coefficient estimates. The benefit of the algorithm was evaluated by measuring the frequency dependent attenuation coefficient of a gelatine phantom containing randomly distributed cellulose scatterers as a homogeneous backscattering component and planar pieces of cooked leek to provide backscattering inhomogeneities. In the phantom the segmentation algorithm was found to improve the accuracy and precision of attenuation coefficient estimates by up to 80% and 90%, respectively. The effect of the algorithm was then measured invivo using 32 radiofrequency B-mode datasets from the breasts of two healthy female volunteers, producing a 5 to 25% reduction in mean attenuation coefficient estimates and a 30 to 50% reduction in standard deviation of attenuation coefficient across different positions within each breast. The results suggest that the segmentation algorithm may improve the accuracy and precision of attenuation coefficient estimates invivo.

中文翻译：

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用于衰减系数估计的基于振幅的超声回波分割

体内超声衰减系数测量是令人感兴趣的，因为它们可以提供对组织病理学的深入了解。还需要它们，以便可以对组织的频率相关超声反向散射系数的测量值进行衰减校正。衰减系数的体内测量具有挑战性，因为它必须从显示大量幅度变化的反向散射信号的深度相关衰减进行估计。在这项研究中，我们描述和评估了一种改进的反向散射方法来估计超声衰减，该方法可以容忍一些反向散射不均匀的存在。这采用自动算法来分割和去除异常强的回声，以减少这些可能引入衰减系数估计的潜在偏差。该算法的好处是通过测量含有随机分布的纤维素散射体作为均匀反向散射成分和煮熟的韭菜平面片以提供反向散射不均匀性的明胶体模的频率相关衰减系数来评估的。在体模中，发现分割算法将衰减系数估计的准确度和精度分别提高了 80% 和 90%。然后使用来自两名健康女性志愿者乳房的 32 个射频 B 模式数据集在体内测量算法的效果，使平均衰减系数估计值降低 5% 至 25%，衰减系数的标准偏差降低 30% 至 50%在每个乳房内的不同位置。