Niemann Tilo, Jerjen Iwan, Hefermehl Lukas, Wang Zhentian, Kubik-Huch Rahel A, Stampanoni Marco
Kantonsspital Baden, Department of Radiology, Baden, Switzerland.
ETH Zurich, Department of Information Technology and Electrical Engineering, Zurich, Switzerland.
Cent European J Urol. 2021;74(3):453-458. doi: 10.5173/ceju.2021.3.0334. Epub 2021 Sep 9.
Occurrence of urinary calculi is a common medical condition. Since treatment and prevention measures depend on the type of stone found, reliable diagnostic tools are required. Dual energy computed tomography (CT) allows for rough classification of the stones found. After extraction, stone composition can be confirmed by laboratory analysis.We investigated to which degree gratings-based X-ray interferometry, which can measure attenuation, refraction and scattering (dark-field) properties of samples, allows for the discrimination of urinary stone type by calculating the ratio (R) of attenuation and scattering signals.
In an experimental setup we investigated 322 renal stone fragments from 96 patients which were extracted during routine clinical practice. Laboratory analysis showed the chemical composition of the urinary stones.These were correlated with dark field analysis of the stone samples. Measurements were performed on a X-rays gratings interferometer prototype. The attenuation, refraction and scattering signals were measured and the R-value calculated.
The spread of R-values of a given type of calculi is large, reducing the specificity of the method. Only uric acid stones can reliably be distinguished (sensitivity of 0.86 at a specificity of 0.9) from the other stones.
Gratings-based dark-field imaging is a non-destructive and potentially non-invasive technique that allows to discriminate between uric acid and non-uric acid stones, which from a clinical point of view represents by far the most important question for stone treatment.
尿结石的发生是一种常见的医学状况。由于治疗和预防措施取决于所发现结石的类型，因此需要可靠的诊断工具。双能计算机断层扫描（CT）可对所发现的结石进行大致分类。结石取出后，可通过实验室分析确定其成分。我们研究了基于光栅的X射线干涉测量法在何种程度上能够通过计算衰减信号与散射信号的比值（R）来鉴别尿结石类型，该方法能够测量样品的衰减、折射和散射（暗场）特性。
在一个实验装置中，我们研究了96例患者在常规临床实践中取出的322块肾结石碎片。实验室分析显示了尿结石的化学成分，并将其与结石样品的暗场分析结果相关联。测量在一台X射线光栅干涉仪原型上进行。测量衰减、折射和散射信号并计算R值。
给定类型结石的R值分布范围很大，降低了该方法的特异性。只有尿酸结石能够可靠地与其他结石区分开来（在特异性为0.9时，灵敏度为0.86）。
基于光栅的暗场成像技术是一种无损且可能无创的技术，能够区分尿酸结石和非尿酸结石，从临床角度来看，这是结石治疗中迄今为止最重要的问题。
