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Theses Doctoral

Developing SCAPE Microscopy for real-time, volumetric imaging at the point-of-care

Patel, Kripa Bharat

Physicians are blind to the microscopic tissue structure that defines tissue type and pathologies during procedures. For diagnosis, tissue must be excised, fixed, and processed for histology, which can take anywhere from 20 minutes to days. This need for tissue excision and processing for microscopic visualization delays decision-making and necessitates repeat procedures. Limited sampling can also never fully eliminate the presence of disease. However, advances in optical sectioning techniques such as confocal and two-photon microscopy, which provide isotropic cellular-level resolution in bulk tissues, have obviated the need to physically section and process tissues for histology. Many optical imaging probes have been developed over the last three decades with the goal of demarcating tissue health in situ, either completely eliminating the need for tissue excision and processing for histopathology or guiding biopsy selection to reduce sampling bias. However, these techniques have faced major barriers to routine and widespread clinical use, including small 2D fields of view, limited contrast, slow imaging speeds and bulky laser sources.

To address this critical need, SCAPE Microscopy, a light sheet-based microscopy technique recently developed in the Hillman lab, was developed for label-free, real-time, volumetric imaging at the point-of-care. SCAPE allows visualization of both cross-sectional and multilayer en face geometries in parallel and real-time, providing a more comprehensive view of tissue architecture than individual histology slides. Furthermore, tissues can be imaged label-free with structure shown through intrinsic fluorescence or in conjunction with intravenous or topical dyes. SCAPE’s video-rate speeds permit 3D stitching of large tissue areas and can withstand in vivo motion, which typically renders point-scanning techniques impractical. Most importantly, SCAPE is shown to allow 3D visualization of key histoarchitectural markers in human kidney biopsies through both endogenous and exogenous fluorophores. In this thesis work, a benchtop system is used for proof-of-concept imaging; however, miniaturized prototypes more suitable for clinical use are also presented.

Further, high-throughput imaging of tissues is a critical but underserved need for bedside biopsy evaluation, as well as large-scale interrogation of structural organization and connectivity in the brain, retina and even whole model organisms. SCAPE provides near giga-voxel per second imaging rates that are well-suited for imaging large-scale ex vivo tissues at isotropic resolution at orders of magnitude faster speeds than point-scanning techniques. To this end, SCAPE was also developed as a versatile imaging platform for structural imaging of large-scale fresh, fixed, cleared and expanded samples for both bedside clinical evaluation and basic science research. It is demonstrated that planar samples of a few millimeters can be fully imaged at cellular resolution in just minutes by combining 3-axis stage-scanning and 3D stitching.

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More About This Work

Academic Units
Biomedical Engineering
Thesis Advisors
Hillman, Elizabeth M.C.
Degree
Ph.D., Columbia University
Published Here
November 24, 2021