Heimbach D, Munver R, Zhong P, Jacobs J, Hesse A, Müller S C, Preminger G M
Department of Urology, Section of Experimental Urology, University of Bonn, Bonn, Germany.
J Urol. 2000 Aug;164(2):537-44.
Standardized and reproducible artificial kidney stone models are important for performing comparative studies of different lithotripsy modalities. The acoustic and mechanical properties of renal calculi dictate the manner by which stones interact with the mechanical stresses produced by shock wave lithotripsy (SWL) or intracorporeal lithotripsy modalities. We have developed a novel artificial kidney stone model that is made of natural substances found in real kidney stones. These stone models appear to be much closer in physical properties to natural kidney stones than previously used stone models.
The acoustic and mechanical properties of six groups of artificial stone models were compared to corresponding natural stones of similar compositions. Moreover, three groups of artificial stone models made of plaster-of-Paris were compared to their natural counterparts. In terms of acoustic properties, stone density was measured using a pycnometer based on Archimedes' principle, whereas longitudinal and transverse (or shear) wave propagation speeds were measured using an ultrasound pulse transmission technique. These values were used to calculate wave impedance and dynamic mechanical properties (bulk modulus, Young's modulus, and shear modulus) of the stones. The microhardness of the stones was measured and the effect of composition on stone fragility was evaluated.
Artificial stones, when compared to natural stones of similar composition, showed similar trends in longitudinal and transverse wave speeds, wave impedance, and dynamic elastic moduli. However, values for the artificial stones were uniformly low compared to those of natural stones, suggesting that these artificial stones may be more amenable to shock wave fragmentation. The results of SWL on stone fragmentation of artificial and natural stones also revealed similar trends with the exception of artificial cystine stones which were found to be the most resistant to shock wave fragmentation.
The results indicate that the physical properties of artificial stones made of natural stone materials are comparable to renal calculi of the same chemical composition. The data suggests that these stone phantoms are suitable for performing standardized and reproducible in vitro investigations, especially with regards to fragility of kidney stones of different chemical compositions during SWL.
标准化且可重复的人工肾结石模型对于开展不同碎石方式的比较研究至关重要。肾结石的声学和力学特性决定了结石与冲击波碎石术（SWL）或体内碎石术所产生的机械应力相互作用的方式。我们开发了一种新型人工肾结石模型，其由真实肾结石中发现的天然物质制成。这些结石模型在物理特性上似乎比先前使用的结石模型更接近天然肾结石。
将六组人工结石模型的声学和力学特性与成分相似的相应天然结石进行比较。此外，将三组由熟石膏制成的人工结石模型与其天然对应物进行比较。在声学特性方面，基于阿基米德原理使用比重瓶测量结石密度，而使用超声脉冲传输技术测量纵波和横波（或剪切波）传播速度。这些值用于计算结石的波阻抗和动态力学特性（体积模量、杨氏模量和剪切模量）。测量结石的显微硬度并评估成分对结石易碎性的影响。
与成分相似的天然结石相比，人工结石在纵波和横波速度、波阻抗以及动态弹性模量方面呈现出相似的趋势。然而，人工结石的值相较于天然结石始终较低，这表明这些人工结石可能更易于被冲击波破碎。SWL对人工结石和天然结石破碎的结果也显示出相似的趋势，但人工胱氨酸结石是最抗冲击波破碎的除外。
结果表明，由天然石材制成的人工结石的物理特性与相同化学成分的肾结石相当。数据表明，这些结石模型适用于进行标准化且可重复的体外研究，特别是关于不同化学成分的肾结石在SWL期间的易碎性。
