Usefulness Of Spectral CT Enterography In Evaluation Of Intestinal Severity In Ileocolonic Crohn’s Disease

Aim: To investigate the value of spectral CTE in evaluation of intestinal severity of ileocolonic Crohn‘s disease.Method: Fifty ileocolonic CD patients were included in this study.They all went through spectral CTE examination and ileocolonoscopy.HBI and CRP were also obtained.Terminal ileum,ascending colon,transverse colon,descending colon,sigmoid and rectum were observed under endoscopy.Then,we classified bowel segments into three categories,namely,endoscopically normal segment,segments with mild lesions and segments with severe lesions according to endoscopic examinations.SES-CD was also calculated.Spectral CT could reconstruct conventional CT images,material decomposition images(iodine-based and waterbased images)and monochromatic images.Bowel wall thickness,bowel wall enhancement,ulcers,comb sign and enlarged lymph nodes were analyzed on conventional CTE images.NIC and λHU were analyzed on spectral CTE images.Parameters in conventional CTE and spectral CTE mode were used to establish logistic regression and comparisons were made to see which mode was better in predicting intestinal activity and severity.Spearman test was used to make correlations between NIC,λHU and SES-CD,CRP and HBI.Results: Qualitative findings,such as bowel enhancement,ulcers at CT images and comb sign progressively increased with endoscopic severity.Quantitative findings,such as wall thickness,NIC and λHU also progressively increased with endoscopic severity.In predicting intestinal activity,bowel enhancement and wall thickness were independent predictors in conventional CTE.Both NIC and λHU were independent predictors in spectral CTE.Compared with conventional CTE,spectral CTE featured higher accuracy(0.999 vs.0.985),sensitivity(99.1% vs.93.4%)and specificity(100% vs.94.4%).In predicting intestinal severity,bowel enhancement,wall thickness and ulcers at CT images were independent predictors in conventional CTE mode.Also,both NIC and λHU were independent predictors in spectral CTE mode.Spectral CTE also featured higher accuracy(0.991 vs.0.971),sensitivity(96.5% vs.92.1%)and specificity(95.8% vs.89.8%)than those in conventional CTE.The combination of parameters in conventional CTE and spectral CTE could further increased diagnostic accuracy(1 and 0.996)and sensitivity(99.4% and 99.2%).The specificity(99.4% and 95.4%)could still maintain at high levels.NIC and λHU also correlated significantly with SES-CD.Conclusions: Quantitative parameters in spectral CTE were superior to common parameters in conventional CTE in predicting intestinal activity and severity of CD.The combination of parameters in spectral CTE and conventional CTE could further improve the diagnostic accuracy.