A Picture Is Worth a Thousand Focal Planes: An Investigation into the Utility of Z-Stacking Software for Image Optimization of Gross Surgical Pathology Specimens

Abstract

Pathology laboratories generally employ rudimentary digital photography platforms as ancillary instruments in the gross examination of surgical specimens. Most platforms provide low-fidelity photographs of limited clinical and educational value. Continued technological gains have fueled advanced imaging methods with broad applications for digital pathology. One such technology, Z-stacking software, stitches together multiple photographs taken at various focal planes to expand the depth of field (DOF) of an image. Herein, we investigate the utility of Z-stacking software, combined with a modern, high-end digital single-lens reflex (DSLR) camera, in providing crisp digital photographs and videos of pathology specimens. 10 surgical pathology specimens, received in the first quarter of 2015, were randomly selected for this study. Specimens were photographed via 2 methods, reflecting our current and prospective image acquisition platforms. Method A utilized SPOT insight camera (Diagnostics Instruments, Model #18.2 Color Mosaic, Sterling Heights, MI), without image optimization. Method B utilized a Canon camera (Canon, EOS Rebel T3 model, Tokyo, JP), followed by image optimization with Helicon Focus software, a commercially available image-processing tool with Z-stacking abilities. All obtained photographs were evaluated on a scale of 1-5 (1 = worst; 5 = best) by authors for the following parameters: (1) DOF, (2) sharpness, (3) color accuracy, (4) exposure, and (5) overall photo quality. For all examined parameters, photos obtained using method B demonstrated higher average scores and displayed overall higher quality. Contemporary DSLR cameras can be combined with commercially available, low-cost Z-stacking software to dramatically increase the quality of gross pathology photographs. Photos obtained using this method were better focused, sharper, more color accurate, and were less commonly over- or underexposed. Furthermore, these techniques can also be applied to improve photomicroscopy and enable 3-dimensional rendering of the specimen images, all of which could potentially enhance educational and clinical experiences.