A look at scanner introduced variation in contrast, resolution, and colour across nine different models of whole slide imaging (WSI) scanner

Variation in digital whole slide images can be introduced across entire the digital pathology pathway, but one source of variation is the WSI scanner itself. We measured the range of variation across 9 different makes and models of WSI scanner using commercial and bespoke test objects. Slides were prepared representing a range of contrast, colour and resolution test signals. Differences in contrast were seen in both a shift of the maximum and minimum contrast levels and the introduction of non-linearity in some scanners. These contrast differences were also reflected in H&E images with additional shifts seen within the eosin colour space for some of the scanners. The resolution test pattern showed a wide variation in the ability of scanners to accurately reproduce the smaller details. This study describes the image variability of nine WSI scanners and highlights the importance of independent quality assessment and control.