Characterization of brain tumours requires neuropathological expertise and is generally performed by histological evaluation and molecular analysis. One emerging technique to assist pathologists in future tumour diagnostics is multimodal optical spectroscopy. In the current clinical routine, tissue preprocessing with formalin is widely established and suitable for spectroscopic investigations since degradation processes impede the measurement of native tissue. However, formalin fixation results in alterations of the tissue chemistry and morphology for example by protein cross-linking. As optical spectroscopy is sensitive to these variations, we evaluate the effects of formalin fixation on multimodal brain tumour data in this proof-of-concept study. Nonfixed and formalin-fixed cross sections of different common human brain tumours were subjected to analysis of chemical variations using ultraviolet and Fourier-transform infrared microspectroscopy. Morphological changes were assessed by elastic light scattering microspectroscopy in the visible wavelength range. Data were analysed with multivariate data analysis and compared with histopathology. Tissue type classifications deduced by optical spectroscopy are highly comparable and independent from the preparation and the fixation protocol. However, formalin fixation leads to slightly better classification models due to improved stability of the tissue. As a consequence, spectroscopic methods represent an appropriate additional contrast for chemical and morphological information in neuropathological diagnosis and should be investigated to a greater extent. Furthermore, they can be included in the clinical workflow even after formalin fixation.

中文翻译：

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以人脑肿瘤横截面为例，福尔马林固定作为组织预处理的多峰光谱学

脑肿瘤的表征需要神经病理学专业知识，并且通常通过组织学评估和分子分析来进行。一种协助病理学家进行未来肿瘤诊断的新兴技术是多峰光谱法。在当前的临床常规中，用福尔马林进行的组织预处理已被广泛建立，并且适合于光谱学研究，因为降解过程阻碍了对天然组织的测量。然而，福尔马林固定例如通过蛋白质交联导致组织化学和形态的改变。由于光谱学对这些变化很敏感，因此在此概念验证研究中，我们评估了福尔马林固定对多峰脑肿瘤数据的影响。使用紫外线和傅立叶变换红外显微技术对不同的普通人脑肿瘤的非固定和福尔马林固定的横截面进行化学变化分析。通过弹性光散射显微术在可见波长范围内评估形态学变化。使用多变量数据分析对数据进行分析，并与组织病理学进行比较。通过光谱学推断的组织类型分类具有高度可比性，并且与制备和固定方案无关。然而，由于组织的稳定性提高，福尔马林固定导致分类模型稍好。作为结果，光谱方法代表了神经病理学诊断中化学和形态学信息的适当附加对比，应进行更大范围的研究。此外，即使在福尔马林固定后，也可以将它们包括在临床工作流程中。