Abstract: Objective To investigate the diagnostic efficiency of MRI combined with diffusion-weighted imaging (DWI) in diagnosis and quantitative evaluation of inflammatory bowel disease (IBD) Methods 20 patients with pathologically diagnosed IBD and 10 patients with normal enteroscopy examination were collected. The MR-score-S of each intestinal segment was analyzed, and the ADC value and intestinal wall thickness was also measured (rectum, sigmoid colon, descending colon, transverse colon, ascending colon and ileum). Using endoscopy as the golden standard, diagnosis efficiency of IBD by quantitative parameters including MR-score-S, ADC value and intestinal wall thickness was analyzed by ROC curve and their correlation with endoscopy scores was also analyzed. Results 162 intestinal segments were analyzed. The area under the ROC curve of MR-score-S, ADC value and the thickness of the bowel wall in diagnosis of IBD was 0.8126, 0.7654 and 0.74, respectively. That of MR-score-S (Without enhancement), MR-score-S (Without DWI) and MR-score-S (Without enhancement or DWI) was 0.785, 0.7988 and 0.7377, respectively. In IBD patients, MR score, ADC value and bowel wall thickness showed statistical correlation with endoscopic grading (P<0.05), and the correlation coefficients were 0.724, -0.43 and 0.519 in UC patients, while those in CD patients were 0.484, -0.392 and 0.331. Conclusion Combined with DWI and ADC value, MRI provides a reliable diagnostic method for IBD, especially in patients with ulcerative colitis. And quantitative assessment of bowel inflammation helps to guide clinical individualized treatment and improve the prognosis of IBD.

Key words: Magnetic resonance imaging (MRI), Diffusion-weighted imaging (DWI), Inflammatory bowel disease (IBD), Apparent diffusion coefficient (ADC)