Evaluation of the Effect of Iodine Staining and Sodium Thiosulfate Clearing on the Quality of X-ray Microtomographic Images and Histological Processing of Small Bowel Biopsies

Histological evaluation of small bowel biopsies remains the gold standard diagnostic and follow-up outcome in celiac disease. X-ray microtomography (µCT) has been introduced as a complementary imaging tool to assess histological changes from the mucosal biopsies, however, this has thus far not been allowing further histological processing. It has been shown that a common contrast agent used in µCT imaging, iodine, can be cleared from a sample using sodium thiosulfate (STS). The purpose of this research was to evaluate the effect of the length of iodine solution (I₂E) staining on the µCT image quality as well as the length of the iodine staining and STS clearing on the quality of the histological processing and resulting hematoxylin and eosin (H&E) stained histological image. A series of I₂E stained small bowel biopsies were imaged using µCT, cleared using STS for various lengths of time, and processed for histology. For reference, one biopsy was only stained with iodine and processed directly without clearing. Images with different staining and clearing times were compared both visually and numerically with contrast-to-noise ratio (CNR) values and color deconvolution. The results demonstrated that the length of I₂E staining has insignificant effect on the quality of the µCT image. Additionally, neither the I₂E staining nor STS clearing times have significant effect on the histological image quality. Interestingly, the H&E staining process rinses most of the remaining iodine from the thin sample.