Intraoperative histology: Lightning 3D histopathology

Harnessing the power of optical microscopy for visualization and analysis of histopathological images

Histopathology is the foundation and gold standard for identifying diseases, and precise quantification of histopathological images can provide the pathologist with objective clues to make a more convincing diagnosis. Optical microscopy (OM), an important branch of optical imaging technology that provides high-resolution images of tissue cytology and structural morphology, has been used in the diagnosis of histopathology and evolved into a new disciplinary direction of optical microscopic histopathology (OMH). There are a number of ex-vivo studies providing applicability of different OMH approaches, and a transfer of these techniques toward in vivo diagnosis is currently in progress. Furthermore, combined with advanced artificial intelligence algorithms, OMH allows for improved diagnostic reliability and convenience due to the complementarity of retrieval information. In this review, we cover recent advances in OMH, including the exploration of new techniques in OMH as well as their applications, and look ahead to new challenges in OMH. These typical application examples well demonstrate the application potential and clinical value of OMH techniques in histopathological diagnosis.

Automated variable power cold microwave tissue processing: A novel universal tissue processing protocol without using formaldehyde and xylene

The tissue processing technique is used to preserve the biological structure of tissue samples harvested from biopsy as closely as possible to their in vivo state for the diagnoses and study of disease on the cellular level. This process includes fixation, dehydration, clearing, paraffin infiltration. The protocol follows paraffin block embedding, microtome slicing, staining, and microscope slide studying. Tissue processing is a time-sensitive task as histopathologists must rapidly prevent the decomposition of tissue samples and promptly provide diagnoses on time. However, there are different tissue processing protocols for processing tissues with different types and sizes. Fatty tissues and tissues thicker than 1.5 mm are more susceptible to human errors when choosing a proper tissue processing protocol when preparing separate batches of tissues. In this research, a novel automated variable power cold microwave tissue processor was developed using a universal tissue processing protocol (processing time of 97 min) to simultaneously process all tissue types up to 4 mm in thickness. The tissue processor operated with a relatively smaller number of reagents without formaldehyde or xylene. These materials cause severe health and safety issues for humans and the environment. The quality of healthy and diseased processed tissues (sizes 1×1×1 to 24×15×4 mm) of fatty, thyroid, breast, placenta, skin, prostate, stomach, and bladder was examined under a light microscope by defining MAS (morphology, artifacts, and staining) criteria for evaluating cellular details, tissue arrangement, tissue integrity, stain uptake, and visual distinction of a tissue structure in light microscopy. It was found that the new tissue processor has successfully processed both healthy and diseased fatty and nonfatty tissue samples, while all tissue samples also met MAS criteria. Light microscopy showed outstanding integrity and arrangement in the tissue structures with an excellent visual distinction.

Rapid pathology of lumpectomy margins with open-top light-sheet (OTLS) microscopy

Open-top light-sheet microscopy is a technique that can potentially enable rapid ex vivo inspection of large tissue surfaces and volumes. Here, we have optimized an open-top light-sheet (OTLS) microscope and image-processing workflow for the comprehensive examination of surgical margin surfaces, and have also developed a novel fluorescent analog of H&E staining that is robust for staining fresh unfixed tissues. Our tissue-staining method can be achieved within 2.5 minutes followed by OTLS microscopy of lumpectomy surfaces at a rate of up to 1.5 cm2/minute. An image atlas is presented to show that OTLS image quality surpasses that of intraoperative frozen sectioning and can approximate that of gold-standard H&E histology of formalin-fixed paraffin-embedded (FFPE) tissues. Qualitative evidence indicates that these intraoperative methods do not interfere with downstream post-operative H&E histology and immunohistochemistry. These results should facilitate the translation of OTLS microscopy for intraoperative guidance of lumpectomy and other surgical oncology procedures.