Department of Systems Design Engineering, PhotoMedicine Labs, University of Waterloo, E7-6416 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.
Department of Systems Design Engineering, illumiSonics, Inc., University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
Sci Rep. 2020 Nov 5;10(1):19121. doi: 10.1038/s41598-020-76155-6.
Histological visualizations are critical to clinical disease management and are fundamental to biological understanding. However, current approaches that rely on bright-field microscopy require extensive tissue preparation prior to imaging. These processes are both labor intensive and contribute to creating significant delays in clinical feedback for treatment decisions that can extend to 2-3 weeks for standard paraffin-embedded tissue preparation and interpretation, especially if ancillary testing is needed. Here, we present the first comprehensive study on the broad application of a novel label-free reflection-mode imaging modality known as photoacoustic remote sensing (PARS) for visualizing salient subcellular structures from various common histopathological tissue preparations and for use in unprocessed freshly resected tissues. The PARS modality permits non-contact visualizations of intrinsic endogenous optical absorption contrast to be extracted from thick and opaque biological targets with optical resolution. The technique was examined both as a rapid assessment tool that is capable of managing large samples (> 1 cm) in under 10 min, and as a high contrast imaging modality capable of extracting specific biological contrast to simulate conventional histological stains such as hematoxylin and eosin (H&E). The capabilities of the proposed method are demonstrated in a variety of human tissue preparations including formalin-fixed paraffin-embedded tissue blocks and unstained slides sectioned from these blocks, including normal and neoplastic human brain, and breast epithelium involved with breast cancer. Similarly, PARS images of human skin prepared by frozen section clearly demonstrated basal cell carcinoma and normal human skin tissue. Finally, we imaged unprocessed murine kidney and achieved histologically relevant subcellular morphology in fresh tissue. This represents a vital step towards an effective real-time clinical microscope that overcomes the limitations of standard histopathologic tissue preparations and enables real-time pathology assessment.
组织学可视化对于临床疾病管理至关重要，也是生物学理解的基础。然而，目前依赖明场显微镜的方法在成像前需要进行广泛的组织准备。这些过程既耗费劳力，又导致临床反馈延迟，特别是在需要辅助测试的情况下，对于治疗决策的反馈可能会延长到 2-3 周。在这里，我们首次全面研究了一种新颖的无标记反射模式成像模式，即光声远程感应 (PARS)，该模式可广泛应用于从各种常见组织病理学组织制备中可视化显著的亚细胞结构，并可用于未经处理的新鲜切除组织。PARS 模式允许从厚而不透明的生物靶标中提取固有内源性光吸收对比，具有光学分辨率。该技术被检查为一种快速评估工具，能够在不到 10 分钟的时间内处理大于 1cm 的大样本，并且作为一种高对比度成像模式，能够提取特定的生物对比度，以模拟传统的组织学染色，如苏木精和伊红 (H&E)。所提出的方法的能力在各种人类组织制备中得到了证明，包括福尔马林固定石蜡包埋组织块和从这些块中切下的未染色幻灯片，包括正常和肿瘤性人脑，以及涉及乳腺癌的乳腺上皮。同样，通过冷冻切片制备的人皮肤的 PARS 图像清楚地显示了基底细胞癌和正常的人类皮肤组织。最后，我们对未经处理的鼠肾进行了成像，并在新鲜组织中实现了具有组织学相关性的亚细胞形态。这是迈向有效的实时临床显微镜的重要一步，克服了标准组织病理学组织制备的局限性，并实现了实时病理学评估。
