Whole slide phase imaging by space-time digital holography for stain-free characterization of breast cancer and fibroadenoma in histological tissues

Abstract Scanning large tissue slides for digital pathology, while necessary for large area coverage, can suffer from ambiguities, biased interpretations, and the inherent limitations of the staining procedure. Here we show that phase-shifting space-time digital holography (PS-STDH) could serve as an efficient digitalization of histopathology slides, encoding their 3D content into 2D wide-field quantitative phase images, while avoiding staining processes. In fact, PS-STDH approach, unlike other interferometric scanning modalities, provides an unambiguous and continuous phase distribution across the entire slide. It resolves phase unwrapping issues as it enables seamless stitching of multiple space-time holograms without phase ambiguities, directly resulting from perfect fringe matching in our hybrid hologram reprojection. Reported results demonstrate a continuous, unambiguous phase mapping over cm-long scans tested on breast cancer and fibroadenoma histopathology slides, while achieving a resolution of 0.98 μ m along the scanning direction and 1.38 μ m perpendicular to it.