Image Quality Assessment of Large Tissue Samples Stained using a Customized Automated Slide Stainer

Whole slide imaging (WSI) creates high-resolution digital images of entire tissue samples, enabling accurate and reliable analysis. Consistency in staining is essential for producing high-quality WSI slides. An automated slide stainer is critical in ensuring precise and uniform staining, especially for larger tissue sections where manual staining can be challenging. However, no large format stainers are currently available on the market. A custom-designed automated slide stainer for large tissue sections was developed to address these issues, having the capability to handle various glass slides from the standard 1” $\times$ 3” glass slides to the customized 2” $\times$ 3”, 5” $\times$ 7” and 6” $\times$ 8” glass slides. The performance of the custom-designed large format automated slide stainer was compared to the Sakura Tissue-Tek Prisma machine and the manual staining method. The image quality of the whole slide images was evaluated using parameters like the signal-to-noise ratio and the consistency of the image histograms. The automated stainer showed a low intra-slide variation of stain intensity, with a lower standard deviation (SD) of 13.005 ± 1.515 compared to the manual method’s SD of 17.315 ± 3.31. In addition, the automated slide staining showed a lower SD (Nissl = 1.795, Hematoxylin and Eosin (H&E) = 2.56) in Signal-to-Noise Ratio (SNR) values compared to manual staining (Nissl = 6.282, H&E = 5.31), indicating excellent staining uniformity. Overall, the automated slide stainer had consistent staining across slides, with a low pairwise distance of 0.0070 ± 0.0017 (Nissl) and 0.0060 ± 0.0003 (H&E). Based on the image evaluation, the custom-designed large-format automated slide stainer was shown to be a reliable, repeatable, and consistent method for staining large tissue samples of sizes up to 150 $\times$ 200 mm.