Cygan Szymon, Januszewicz Magdalena
Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, Warsaw, Poland.
Medical University of Warsaw, II Department of Clinical Radiology, Warsaw, Poland.
J Ultrason. 2016 Dec;16(67):329-338. doi: 10.15557/JoU.2016.0033. Epub 2016 Dec 30.
Since there have been only few works reporting the diagnosis of kidneys using Acoustic Radiation Force Impulse technique and those works do not provide consistent results of shear wave velocity measurements in renal tissue, we have decided to use kidney phantoms with known properties to examine the reliability of the method itself in a controlled setup similar to kidneys examination.
Four gelatin-based phantoms imitating different clinical situations were manufactured - two with thick and two with thin renal cortex, each type at a depth similar to a normal-weight or overweight patient. For each phantom, a series of interest points was chosen and for each point 20 Shear Wave Velocity measurements were taken using the build-in Virtual Touch Tissue Quantification tool in a Siemens Acuson S2000 ultrasound scanner equipped with a 6C1 HD Transducer (Siemens Mountainview, USA).
Mean Shear Wave Velocity values obtained for all the examined points ranged from 2.445 to 3.941 m/s, with standard deviation exceeding 0.1 in only one case out of 29 points, but differing significantly between all points.
The obtained results indicate that the method is highly reliable as long as the measurement volume contains a uniform tissue region. If the measurement window covers a region with different properties even partially, the obtained results are affected. The variance of measured values on the other hand is not affected by the said non-uniformity of material under examination. Furthermore, the variance of measured values does not show a clear dependency on the depth at which the shear wave velocities are measured.
由于仅有少数研究报道了使用声辐射力脉冲技术诊断肾脏的情况，且这些研究并未提供肾组织剪切波速度测量的一致结果，我们决定使用具有已知特性的肾脏模型，在类似于肾脏检查的受控设置中检验该方法本身的可靠性。
制作了四个模拟不同临床情况的明胶基模型——两个肾皮质厚的和两个肾皮质薄的，每种类型的深度类似于正常体重或超重患者。对于每个模型，选择了一系列感兴趣点，并使用配备6C1 HD换能器的西门子Acuson S2000超声扫描仪中的内置虚拟触诊组织定量工具，对每个点进行20次剪切波速度测量（西门子，美国山景城）。
所有检查点获得的平均剪切波速度值在2.445至3.941米/秒之间，29个点中只有一个点的标准差超过0.1，但所有点之间存在显著差异。
所得结果表明，只要测量体积包含均匀的组织区域，该方法就高度可靠。如果测量窗口即使部分覆盖具有不同特性的区域，所获得的结果也会受到影响。另一方面，测量值的方差不受被测材料上述不均匀性的影响。此外，测量值的方差并未显示出对测量剪切波速度的深度有明显的依赖性。
