肾结石的大小和体积在 CT 中的表现：采集技术和图像重建参数的影响。

Size and volume of kidney stones in computed tomography: Influence of acquisition techniques and image reconstruction parameters.

机构信息

University of Cologne, Faculty of Medicine and University Hospital Cologne, Institute for Diagnostic and Interventional Radiology, Kerpener Str. 62, 50937, Cologne, Germany.

University of Cologne, Faculty of Medicine and University Hospital Cologne, Department of Urology, Kerpener Str. 62, 50937, Cologne, Germany.

出版信息

Eur J Radiol. 2020 Nov;132:109267. doi: 10.1016/j.ejrad.2020.109267. Epub 2020 Sep 6.

DOI:10.1016/j.ejrad.2020.109267

PMID:32949914

Abstract

PURPOSE

Computed tomography (CT) is routinely used to assess suspected urolithiasis. Information obtained from CT include presence, location and size of stones, with the latter frequently determining treatment strategy. While there is consensus regarding measurements procedures of kidney stones, influence of radiation dose and reconstruction techniques on stone measurements are unknown. The purpose of this study was to systematically evaluate the influence of these technical determinants on kidney stone size measurements.

METHOD

47 kidney stones of different composition were scanned using a 64-row-multi-detector CT in a 3D-printed, semi-anthropomorphic phantom. Reference stone sizes were measured manually with a digital caliper (Man-M). Stones were imaged with 2 and 10 mGy CTDI. Images were reconstructed using filtered-back-projection, hybrid-iterative and model-based-iterative reconstruction algorithms (FBP, HIR, MBIR) in combination with different kernels and denoising levels. All stones underwent semi-automatic, threshold-based segmentation for computation of maximum diameter and volume. Statistics were conducted using ANOVA ± correction for multiple comparisons.

RESULTS

Overall stone size as compared to manual measurements was overestimated in CT (10.0 ± 3.1 vs. 8.8 ± 2.9 mm, p < 0.05) yet showing a good correlation (R = 0.66). Radiation dose and denoising levels did not significantly influence measurements (p > 0.05). MBIR and sharp kernels showed closest agreement with Man-M (9.3 ± 3.1 vs. 8.8 ± 2.9 mm, p < 0.05). Differences within single stones were as high as 40 % (e.g. Man-M: 5.9 mm, CT: 7.3-12.0 mm).

CONCLUSIONS

CT-based measurements of kidney stone size appear unaffected by radiation dose and denoising technique, whereas reconstruction algorithms and kernels demonstrate a relevant impact on size measurements. Smallest differences were found using MBIR with a sharp kernel.

摘要

目的

计算机断层扫描（CT）常用于评估疑似尿路结石。CT 提供的信息包括结石的存在、位置和大小，后者通常决定治疗策略。虽然对于肾结石的测量程序有共识，但辐射剂量和重建技术对结石测量的影响尚不清楚。本研究的目的是系统评估这些技术因素对肾结石大小测量的影响。

方法

使用 64 排多探测器 CT 在 3D 打印的半人体模型体模中对 47 颗不同成分的肾结石进行扫描。手动用数字卡尺（Man-M）测量参考结石大小。使用 2 和 10mGy CTDI 对结石进行成像。使用滤波反投影、混合迭代和基于模型的迭代重建算法（FBP、HIR、MBIR）结合不同的内核和降噪水平对图像进行重建。所有结石均进行半自动、基于阈值的分割，以计算最大直径和体积。使用方差分析（ANOVA）进行统计学分析，并进行了多重比较校正。

结果

与手动测量相比，CT 测量的总体结石大小（10.0±3.1 与 8.8±2.9mm，p<0.05）被高估，但具有良好的相关性（R=0.66）。辐射剂量和降噪水平对测量没有显著影响（p>0.05）。MBIR 和锐利内核与 Man-M 最接近（9.3±3.1 与 8.8±2.9mm，p<0.05）。单个结石内的差异高达 40%（例如，Man-M：5.9mm，CT：7.3-12.0mm）。