From the Chair of Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Garching.
Clinic for Birds, Small Mammals, Reptiles, and Ornamental Fish, Center for Clinical Veterinary Medicine, LMU University of Munich, Oberschleißheim.
Invest Radiol. 2020 Aug;55(8):494-498. doi: 10.1097/RLI.0000000000000671.
The aim of this study was to evaluate the potential of x-ray dark-field radiography for the noninvasive detection of monosodium urate (MSU) crystals as a novel diagnostic tool for gout.
Contrast-to-noise ratios of MSU crystals in conventional radiography and dark-field radiography have been compared in a proof of principle measurement. Monosodium urate crystals have been injected into mouse legs in an ex vivo experimental gout setup. Three radiologists independently evaluated the images for the occurrence of crystal deposits in a blinded study for attenuation images only, dark-field images only, and with both images available for a comprehensive diagnosis. All imaging experiments have been performed at an experimental x-ray dark-field setup with a 3-grating interferometer, a rotating anode tube (50 kVp), and a photon-counting detector (effective pixel size, 166 μm).
X-ray dark-field radiography provided a strong signal increase for MSU crystals in a physiological buffer solution compared with conventional attenuation radiography with a contrast-to-noise ratio increase from 0.8 to 19.3. Based on conventional attenuation images only, the reader study revealed insufficient diagnostic performance (sensitivity, 11%; specificity, 92%) with poor interrater agreement (Cohen's coefficient κ = 0.031). Based on dark-field images, the sensitivity increased to 100%, specificity remained at 92%, and the interrater agreement increased to κ = 0.904. Combined diagnosis based on both image modalities maximized both sensitivity and specificity to 100% with absolute interrater agreement (κ = 1.000).
X-ray dark-field radiography enables the detection of MSU crystals in a mouse-based gout model. The simultaneous avaliability of a conventional attenuation image together with the dark-field image provides excellent detection rates of gout deposits with high specificity.
本研究旨在评估 X 射线暗场射线照相术在无创检测单钠尿酸盐 (MSU) 晶体方面的潜力，将其作为痛风的一种新型诊断工具。
在原理验证测量中比较了常规射线照相术和暗场射线照相术的 MSU 晶体的对比噪声比。在离体实验性痛风模型中，将单钠尿酸盐晶体注入小鼠腿部。三位放射科医生在一项盲法研究中，仅对衰减图像、暗场图像和两种图像均可用的综合诊断进行了独立评估，以评估晶体沉积物的发生情况。所有成像实验均在具有 3 个光栅干涉仪、旋转阳极管 (50 kVp) 和光子计数探测器 (有效像素尺寸为 166 μm) 的实验性 X 射线暗场设置中进行。
与常规衰减射线照相术相比，X 射线暗场射线照相术在生理缓冲液中为 MSU 晶体提供了强烈的信号增强，对比噪声比从 0.8 增加到 19.3。仅基于常规衰减图像，读者研究显示诊断性能不足（敏感性为 11%，特异性为 92%），观察者间一致性较差（Cohen 系数 κ = 0.031）。基于暗场图像，敏感性增加到 100%，特异性保持在 92%，观察者间一致性增加到 κ = 0.904。基于两种成像方式的联合诊断使敏感性和特异性均达到 100%，观察者间一致性达到绝对一致（κ = 1.000）。
X 射线暗场射线照相术可在基于小鼠的痛风模型中检测 MSU 晶体。常规衰减图像与暗场图像的同时可用性为痛风沉积物的高特异性提供了极好的检测率。
