Digitizing Whole Slide Images from H&E Slides

H&E slides were digitized into whole slide images at 20× or 40× using the Panoramic SCAN 150 (3DHISTECH Ltd, Budapest, Hungary). For women with good-quality slides, up to six slides from different tissue blocks were digitized. H&E slides that were not digitized were due to poor quality, slides too thick to fit into scanner, and plastic mounting coverslips. Attempts to create new H&E slides were not always possible due to missing (or returned to hospital) blocks, old-style blocks not created using tissue cassettes, or poor-quality blocks [22 (link)]. Out of all controls in the original nested case–control study (n = 1920), 1083 (or 56%) had their slides successfully digitized into whole slide images (WSI) (Fig. 1). Women with and without available tissue readings had similar distributions of breast cancer risk factors [23 (link)].