Multimodal Imaging-Based Anatomical Characterization of DSS-Induced Experimental Ulcerative Colitis in Rat Model

Ulcerative colitis (UC), a chronic inflammatory bowel disease characterized by progressive structural and functional alterations of colon, necessitating reliable non-invasive imaging techniques for accurate disease characterization and longitudinal monitoring.

The diagnostic performance of integrated multimodal imaging framework combining magnetic resonance imaging (MRI), micro-computed tomography (micro-CT) and high-frequency ultrasonography for comprehensive anatomical assessment of DSS-induced experimental ulcerative colitis in rats was evaluated. Adult Sprague-Dawley rats were randomized to control and dextran sulfate sodium (DSS)-treated group and underwent standardized clinical evaluation, multimodal imaging, gross anatomical examination, and histopathological validation. Quantitative imaging biomarkers, including bowel wall thickness, luminal diameter, edema volume, wall irregularity, vascularity index and intestinal motility, were measured regionally within the proximal, middle and distal colon, compared with pathological injury scores.

DSS administration caused progressive weight loss, increased Disease Activity Index scores, colon shortening, bowel wall thickening, mural edema, luminal narrowing, vascular remodeling and severe epithelial injury, with predominant distal colon involvement. MRI provided superior soft-tissue characterization, micro-CT accurately quantified three-dimensional structural remodeling, and ultrasonography enabled dynamic assessment of bowel morphology, vascular perfusion, and motility. Imaging-derived biomarkers demonstrated strong correlations with gross pathological and histological findings, integrated multimodal model achieved the highest diagnostic performance with an area under the receiver operating characteristic curve of 0.997, 96.7% sensitivity, 100% specificity, and excellent inter-observer reproducibility.

The proposed multimodal imaging framework represents a robust, reproducible, and biologically validated platform for non-invasive longitudinal assessment of experimental ulcerative colitis and offers considerable potential for preclinical therapeutic evaluation and translational gastrointestinal imaging research.