Horng Annie, Stroebel Johannes, Geith Tobias, Milz Stefan, Pacureanu Alexandra, Yang Yang, Cloetens Peter, Lovric Goran, Mittone Alberto, Bravin Alberto, Coan Paola
Department of Clinical Radiology, Faculty of Medicine, Ludwig-Maximilians-University, Marchioninistr. 15, 81377, Munich, Germany.
RZM - Radiologisches Zentrum Munich-Pasing, Pippinger Str. 25, 81245, Munich, Germany.
J Biomed Sci. 2021 Jun 7;28(1):42. doi: 10.1186/s12929-021-00739-1.
The evolution of cartilage degeneration is still not fully understood, partly due to its thinness, low radio-opacity and therefore lack of adequately resolving imaging techniques. X-ray phase-contrast imaging (X-PCI) offers increased sensitivity with respect to standard radiography and CT allowing an enhanced visibility of adjoining, low density structures with an almost histological image resolution. This study examined the feasibility of X-PCI for high-resolution (sub-) micrometer analysis of different stages in tissue degeneration of human cartilage samples and compare it to histology and transmission electron microscopy.
Ten 10%-formalin preserved healthy and moderately degenerated osteochondral samples, post-mortem extracted from human knee joints, were examined using four different X-PCI tomographic set-ups using synchrotron radiation the European Synchrotron Radiation Facility (France) and the Swiss Light Source (Switzerland). Volumetric datasets were acquired with voxel sizes between 0.7 × 0.7 × 0.7 and 0.1 × 0.1 × 0.1 µm. Data were reconstructed by a filtered back-projection algorithm, post-processed by ImageJ, the WEKA machine learning pixel classification tool and VGStudio max. For correlation, osteochondral samples were processed for histology and transmission electron microscopy.
X-PCI provides a three-dimensional visualization of healthy and moderately degenerated cartilage samples down to a (sub-)cellular level with good correlation to histologic and transmission electron microscopy images. X-PCI is able to resolve the three layers and the architectural organization of cartilage including changes in chondrocyte cell morphology, chondrocyte subgroup distribution and (re-)organization as well as its subtle matrix structures.
X-PCI captures comprehensive cartilage tissue transformation in its environment and might serve as a tissue-preserving, staining-free and volumetric virtual histology tool for examining and chronicling cartilage behavior in basic research/laboratory experiments of cartilage disease evolution.
软骨退变的演变过程仍未完全明晰，部分原因在于其厚度薄、X 线不透射性低，因而缺乏能充分解析的成像技术。与标准 X 线摄影和 CT 相比，X 线相衬成像（X-PCI）具有更高的灵敏度，能够以近乎组织学图像分辨率增强对相邻低密度结构的可视性。本研究探讨了 X-PCI 用于高分辨率（亚）微米级分析人软骨样本组织退变不同阶段的可行性，并将其与组织学及透射电子显微镜检查结果进行比较。
从人膝关节处死后提取 10 个用 10%福尔马林保存的健康及中度退变的骨软骨样本，使用欧洲同步辐射装置（法国）和瑞士光源（瑞士）的同步辐射，通过四种不同的 X-PCI 断层扫描设置对其进行检查。采集体数据集，体素大小在 0.7×0.7×0.7 至 0.1×0.1×0.1 微米之间。数据通过滤波反投影算法重建，使用 ImageJ、WEKA 机器学习像素分类工具和 VGStudio max 进行后处理。为进行相关性分析，对骨软骨样本进行组织学和透射电子显微镜检查处理。
X-PCI 能在（亚）细胞水平对健康及中度退变的软骨样本进行三维可视化，与组织学和透射电子显微镜图像具有良好的相关性。X-PCI 能够分辨软骨的三层结构及其结构组织，包括软骨细胞形态变化、软骨细胞亚群分布及（重新）组织以及其细微的基质结构。
X-PCI 能捕捉软骨组织在其环境中的全面转变，可作为一种无需染色且能进行体积测量的虚拟组织学工具，用于在软骨疾病演变的基础研究/实验室实验中检查和记录软骨行为。
