Richter Vivien, Willner Marian S, Henningsen John, Birnbacher Lorenz, Marschner Mathias, Herzen Julia, Kimm Melanie A, Noël Peter B, Rummeny Ernst J, Pfeiffer Franz, Fingerle Alexander A
Department of Diagnostic and Interventional Radiology, Eberhard Karls Universität Tübingen, Hoppe-Seyler-Weg 3, 72076 Tuebingen, Germany.
Department of Physics & Institute of Medical Engineering, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany.
Eur J Radiol. 2017 Jan;86:99-104. doi: 10.1016/j.ejrad.2016.11.014. Epub 2016 Nov 8.
X-ray phase-contrast imaging (PCI) provides additional information beyond absorption characteristics by detecting the phase shift of the X-ray beam passing through material. The grating-based system works with standard polychromatic X-ray sources, promising a possible clinical implementation. PCI has been shown to provide additional information in soft-tissue samples. The aim of this study was to determine if ex vivo quantitative phase-contrast computed tomography (PCCT) may differentiate between pathologic fluid collections.
PCCT was performed with the grating interferometry method. A protein serial dilution, human blood samples and 17 clinical samples of pathologic fluid retentions were imaged and correlated with clinical chemistry measurements. Conventional and phase-contrast tomography images were reconstructed. Phase-contrast Hounsfield Units (HUp) were used for quantitative analysis analogously to conventional HU. The imaging was analyzed using overall means, ROI values as well as whole-volume-histograms and vertical gradients. Contrast to noise ratios were calculated between different probes and between imaging methods.
HUp showed a very good linear correlation with protein concentration in vitro. In clinical samples, HUp correlated rather well with cell count and triglyceride content. PCI was better than absorption imaging at differentiating protein concentrations in the protein samples as well as at differentiating blood plasma from cellular components. PCI also allowed for differentiation of watery samples (such as lymphoceles) from pus.
Phase-contrast computed tomography is a promising tool for the differentiation of pathologic fluids that appear homogenous with conventional attenuation imaging.
X射线相衬成像（PCI）通过检测穿过材料的X射线束的相移，提供了超越吸收特性的额外信息。基于光栅的系统可与标准多色X射线源配合使用，有望实现临床应用。PCI已被证明能在软组织样本中提供额外信息。本研究的目的是确定离体定量相衬计算机断层扫描（PCCT）是否可区分病理性积液。
采用光栅干涉法进行PCCT。对蛋白质系列稀释液、人体血液样本和17份病理性液体潴留的临床样本进行成像，并与临床化学测量结果相关联。重建传统断层扫描图像和相衬断层扫描图像。相衬亨氏单位（HUp）用于类似于传统HU的定量分析。使用总体均值、感兴趣区（ROI）值以及全容积直方图和垂直梯度对成像进行分析。计算不同样本之间以及成像方法之间的对比噪声比。
HUp在体外与蛋白质浓度呈现出非常良好的线性相关性。在临床样本中，HUp与细胞计数和甘油三酯含量的相关性相当好。在区分蛋白质样本中的蛋白质浓度以及区分血浆与细胞成分方面，PCI比吸收成像更好。PCI还能够区分水样样本（如淋巴囊肿）和脓液。
相衬计算机断层扫描是一种有前景的工具，可用于区分在传统衰减成像中表现为均匀的病理性液体。
