Accurately determining the attenuation along the propagation path leading to a region of interest could significantly improve diagnostic ultrasound tissue characterization since tissue characterization requires exact compensation for the frequency-dependent attenuation along the propagation path. In a previous study (JASA, 124:1367, 2008), it was shown that the total attenuation can be determined by using the backscattered echoes from multiple sources. The preliminary computer simulation results, had an average error between −0.3 and +0.2 dB/MHz for the cases tested with a trend towards increasing error with increasing correlation length (i.e., characteristic size of the tissue microstructure of the scattering medium) and attenuation along the propagation path. Therefore, the goal of this study was to improve the accuracy of previously derived algorithm and reduce the dependence of the algorithm on correlation length and attenuation. In this study, the previous derivations were redone and the assumptions made by the algorithm regarding the scattering properties of the medium and the shape of the backscattered power spectrum were relaxed. The revised algorithm was then verified using computer simulations of five sources (6, 8, 10, 12, and 14 MHz, 50% bandwidth) exposing a homogeneous tissue region. The simulated tissue had microstructure following a Gaussian spatial correlation function (i.e., exp (−0.827(kaeff)2) where k is the wavenumber) with effective radii, aeff, of 5–55 μm (one size per simulated case) placed at a density of 250/mm3 (∼5 scatterers/resolution cell for 14 MHz transducer). The attenuation of the tissue was also varied from 0.1 to 0.9 dB/cm-MHz. The computer simulations demonstrated that the modifications significantly improved the accuracy of the algorithm resulting in average errors between −0.04 and 0.1 dB/MHz which is three times better than the error performance of the original algorithm.
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机译：由于组织表征需要对沿传播路径的频率相关衰减进行精确补偿，因此准确确定沿导致感兴趣区域的传播路径的衰减可以显着改善超声诊断组织的特征。在先前的研究（JASA，124：1367，2008）中，表明可以通过使用来自多个源的反向散射回波来确定总衰减。初步的计算机模拟结果表明，对于所测试的情况，平均误差在-0.3至+0.2 dB / MHz之间，并且随着相关长度（即，散射介质的组织微结构的特征尺寸）的增加和随着衰减的增加，误差趋向于增加。传播路径。因此，本研究的目的是提高先前导出算法的准确性，并减少算法对相关长度和衰减的依赖性。在这项研究中，重做了先前的推导，并放宽了算法对介质的散射特性和反向散射功率谱的形状所作的假设。然后使用暴露于同质组织区域的五个信号源（6、8、10、12和14 MHz，50％带宽）的计算机仿真来验证修改后的算法。模拟的组织具有遵循高斯空间相关函数（即，exp（-0.827（kaeff）2，其中k是波数））的微观结构，有效半径aeff为5-55μm（每个模拟病例一个大小），放置在密度为250 / mm3（对于14 MHz传感器，约5个散射体/分辨率单元）。组织的衰减也从0.1到0.9 dB / cm-MHz变化。计算机仿真表明，这些修改显着提高了算法的准确性，导致平均误差在-0.04至0.1 dB / MHz之间，是原始算法的错误性能的三倍。
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