Significance: Histopathological analysis of tissues is an essential tool for grading, staging, diagnosing, and resecting cancers and other malignancies. Current histopathological imaging techniques require substantial sample processing, prior to staining with hematoxylin and eosin (H&E) dyes, to highlight nuclear and cellular morphology. Sample preparation and staining is resource intensive and introduces potential for variability during sample preparation. Aim: We present a method for direct label-free histopathological assessment of formalin-fixed paraffin-embedded tissue blocks and thin tissue sections using a dual-contrast photoacoustic remote sensing (PARS) microscopy system. Approach: To emulate the nuclear and cellular contrast of H&E staining, we leverage unique properties of the PARS system. Here, the ultraviolet excitation PARS microscope takes advantage of DNA’s unique optical absorption to provide nuclear contrast analogous to hematoxylin staining of cell nuclei. Concurrently, the optical scattering contrast of the PARS detection system is leveraged to provide bulk tissue contrast reminiscent of eosin staining of cell membranes. Results: We demonstrate the efficacy of this technique by imaging human breast tissue and human skin tissues in formalin-fixed paraffin-embedded tissue blocks and frozen sections, respectively. Salient nuclear and extranuclear features such as cancerous cells, glands and ducts, adipocytes, and stromal structures such as collagen are captured. Conclusions: The presented dual-contrast PARS microscope enables label-free visualization of tissues with contrast and quality comparable to the current gold standard for histopathological analysis. Thus, the proposed system is well positioned to augment existing histopathological workflows, providing histological imaging directly on unstained tissue blocks and sections.

中文翻译：

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双对比光声遥感显微镜单次采集无标记组织学样成像

意义：组织的组织病理学分析是对癌症和其他恶性肿瘤进行分级、分期、诊断和切除的重要工具。当前的组织病理学成像技术需要大量样品处理，然后再用苏木精和伊红 (H&E) 染料染色，以突出细胞核和细胞形态。样品制备和染色是资源密集型的，并且在样品制备过程中引入了可变性的可能性。目的：我们提出了一种使用双对比光声遥感 (PARS) 显微镜系统对福尔马林固定石蜡包埋的组织块和薄组织切片进行直接无标记组织病理学评估的方法。方法：为了模拟 H&E 染色的核和细胞对比，我们利用了 PARS 系统的独特特性。这里，紫外激发PARS显微镜利用DNA独特的光吸收提供类似于细胞核苏木精染色的核对比。同时，PARS 检测系统的光学散射对比度被用来提供大量组织对比度，让人联想到细胞膜的伊红染色。结果：我们通过分别在福尔马林固定的石蜡包埋组织块和冰冻切片中对人体乳房组织和人体皮肤组织进行成像来证明该技术的功效。捕获显着的核和核外特征，例如癌细胞、腺体和导管、脂肪细胞和基质结构（例如胶原蛋白）。结论：所提出的双对比度 PARS 显微镜可实现组织的无标记可视化，其对比度和质量可与当前组织病理学分析的金标准相媲美。因此，所提议的系统可以很好地增强现有的组织病理学工作流程，直接在未染色的组织块和切片上提供组织学成像。