Background/

Objectives: Inflammatory bowel disease (IBD), encompassing Crohn's disease and ulcerative colitis, is characterized by cycles of inflammation and tissue remodeling that can culminate in fibrosis. Differentiating between early inflammatory and fibrotic bowel wall changes remains a diagnostic challenge due to overlapping imaging features. This study aimed to assess the potential of elastography, specifically pixel histogram analysis, as a non-invasive method to identify acute inflammatory changes in a rat model of 2,4,6-trinitrobenzenesulfonic (TNBS)-induced colitis.

Methods: Female CRL:Wi rats were randomized into control and experimental groups, with the latter receiving intracolonic TNBS to induce acute colitis. On day 7 post-induction, all animals underwent ultrasonographic and strain elastographic assessment of the distal colon using a standardized protocol. Histogram-based analysis of red, green, and blue pixel distributions was performed on elastographic video frames. Results were compared with histologic grading of inflammation and fibrosis using hematoxylin-eosin and Masson's trichrome staining.

Results: Rats with TNBS-induced colitis exhibited significant weight loss, increased bowel wall thickness (31.5% vs. controls, p < 0.01), and elevated elastographic pixel intensity across all color channels (p < 0.05). Histologically, experimental animals showed severe inflammation and early submucosal fibrosis. A strong positive correlation was found between elastographic histogram values and histologic fibrosis scores (r = 0.86, p < 0.01), confirming the technique's diagnostic relevance.

Conclusions: Elastographic pixel histogram analysis is a reproducible, non-invasive approach capable of distinguishing acute inflammatory changes and early fibrotic remodeling in experimental colitis. These findings support its potential application as a diagnostic adjunct in the early assessment and monitoring of IBD-related bowel wall changes.