Interlaboratory comparison of ultrasonic backscatter coefficient measurements from 2 to 9 MHz
Interlaboratory comparison of ultrasonic backscatter coefficient measurements from 2 to 9 MHz
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DOI：
10.7863/jum.2005.24.9.1235
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发表时间：
2005-09-01
影响因子：
2.3
通讯作者：
Yuan, JR
中科院分区：
文献类型：
--
作者：
Wear, KA;Stiles, TA;Yuan, JR
Objective.与衰减系数和声速一样，反向散射系数是一种基本的超声特性，已用于表征许多组织。不幸的是，目前超声背向散射测量的标准化程度远低于其他两种测量，这可由美国医学超声研究所（AIUM）先前发起的超声背向散射、衰减和速度测量的实验室间比较所证明（J Ultrasound Med 1999; 18：615-631）。为了探索这些差异的原因，AIUM教育和研究基金会最近支持了第二次实验室间比较，将频率范围的上限从7 MHz扩展到9 MHz。方法.向11个实验室提供了在威斯康星州大学（麦迪逊，WI）设计和制造的标准测试对象。每个实验室被要求进行声速，衰减系数和后向散射系数的超声波测量。在进行测量时，每个实验室对测试对象的超声特性值不知情。结果11个实验室中有8个提交了结果。后向散射系数测量值的绝对值变化范围约为2个数量级。如果排除1个离群实验室的结果，则范围缩小至约1个数量级。关于后向散射的频率依赖性的一致性优于先前实验室间比较中的报告。例如，当散射体与超声波波长相比较小时，由参与实验室获得的实验频率相关的反向散射系数数据通常与预期的瑞利散射行为（与频率的四次方成比例）一致。结论.需要使反向散射测量方法更加标准化。反向散射的频率依赖性的测量比绝对幅度的测量更一致。
Objective. As are the attenuation coefficient and sound speed, the backscatter coefficient is a fundamental ultrasonic property that has been used to characterize many tissues. Unfortunately, there is currently far less standardization for the ultrasonic backscatter measurement than for the other two, as evidenced by a previous American Institute of Ultrasound in Medicine (AIUM)-sponsored inter-laboratory comparison of ultrasonic backscatter, attenuation, and speed measurements (J Ultrasound Med 1999; 18:615-631). To explore reasons for these disparities, the AIUM Endowment for Education and Research recently supported this second interlaboratory comparison, which extends the upper limit of the frequency range from 7 to 9 MHz. Methods. Eleven laboratories were provided with standard test objects designed and manufactured at the University of Wisconsin (Madison, WI). Each laboratory was asked to perform ultrasonic measurements of sound speed, attenuation coefficients, and backscatter coefficients. Each laboratory was blinded to the values of the ultrasonic properties of the test objects at the time the measurements were performed. Results. Eight of the 11 laboratories submitted results. The range of variation of absolute magnitude of backscatter coefficient measurements was about 2 orders of magnitude. If the results of 1 outlier laboratory are excluded, then the range is reduced to about 1 order of magnitude. Agreement regarding frequency dependence of backscatter was better than reported in the previous interlaboratory comparison. For example, when scatterers were small compared with the ultrasonic wavelength, experimental frequency-dependent backscatter coefficient data obtained by the participating laboratories were usually consistent with the expected Rayleigh scattering behavior (proportional to frequency to the fourth power). Conclusions. Greater standardization of backscatter measurement methods is needed. Measurements of frequency dependence of backscatter are more consistent than measurements of absolute magnitude.