A ROC Curve Study Of Dual Sources CT Enterography In Distinguishing The Activity Of Crohn's Disease

Background:Crohn's disease(CD)is a kind of chronic inflammatory granulomatous disease with unknown etiology.It can affect any portion of the gastrointestinal tract,from the mouth to the anus,while the terminal ileum is most commonly affected.Crohn's disease is a kind of transmural inflammatory disease,complicated with fistulas,abscesses,and strictures.The treatment of CD depends on not only site,behaviour and the severity of the disease,but also the activity of the disease.So it is important to identify the affected portion,the behaviour of CD and the activity of CD.So far lots of diagnostic tools can help to diagnose and evaluate CD such as Crohn's Disease Activity Index(CDAI),serum biomarkers including C-reactive protein(CRP),erythrocyte sedimentation rate(ESR),endoscopy,barium enema examination,CT enterography(CTE)and MR enterography(MRE).They have their own advantages and disadvantages.CDAI is a symptom-based disease activity index,which is subjectively designed and often unreliable.And another disadvantage of CDAI for measuring disease severity in CD is that they measure inflammatory activity at a certain time point.However,CD is a chronic destructive disease that causes a progressive loss of bowel structures and function.CRP and ESR are standard laboratory surrogates of the acute phase response to inflammation.Both CRP and ESR elevate in the acute active phase of CD,but they're not the specific serum biomarker for CD,they elevate in other infection,trauma and autoimmune diseases.Endoscopy can evaluate the intestine mucous and biopsy in progress.The most useful endoscopic features of CD are discontinuous involvement,fissures,and cobble stoning.But endoscopy is invasive,expensive,and exposing patients to inherent procedural risks.When there is severe,active disease,the value of endoscopy is limited by a higher risk of bowel perforation and diagnostic errors.When there is severe stricture,capsule endoscope's retention should be considered.Indeed,endoscopy can assess mucosal inflammation,but in a transmural disease like CD,might not be enough.Barium enema examination can detect the mucosal and the luminal disease,but it can't help with the extramural complications,and has a considerably lower sensitivity for the detection of small bowel lesions.Norma abdominal CT scan can help with the extraluminal complications like penetrating complications,mesenteric hypertrophy with fat accumulation,and hypervascularization,but it can't well detect the luminal and the mucosal lesions.CTE and MRE are the current standards for assessing the small intestine.They take the advantage of both barium enema examination and normal abdominal CT.Both techniques can establish disease extension and activity based on wall thickness and increased intravenous contrast enhancement,mesenteric hypertrophy with fat accumulation,and hypervascularization(comb sign),with the highest diagnostic accuracy for the detection of intestinal involvement of CD including extramural complications.CT and MR are also the most accurate techniques to detect presence of extraluminal complications.They are widely used in recent years.CTE or MRE could potentially serve this purpose as they are noninvasive imaging modalities that can provide a more global transmural evaluation of the intestinal wall.The consensus of China recommend the CTE and MRE should be taken if possible.In China,CTE has greater availability and is less time-consuming than MRE.CTE is widely used than MRE.CTE is a common non-invasive diagnostic tool,more acceptable to patients.CTE has a high sensitivity for the detection of enteric CD and has been validated in comparison with several clinical,pathological,radiographic,and endoscopic techniques.Doctors and patients prefer CTE due to its non-invasive nature.CD is a transmural disease,which is characterized by intestinal wall thickening with fibrosis,penetrating complications,mesenteric hypertrophy with fat accumulation,and hypervascularization(comb sign).Former studies showed that the clinical activities associate with the thickening of the bowels,the enhancement of the bowel walls,the stricture of the bowels,the comb sign,the enlarged mesenteric lymph nodes,fistulas,ulcers or abscess.Accordingly,accurate methods for assessment of disease activity in CD should provide a more global transmural evaluation of the intestinal wall.Nowadays the clinical evaluation of inflammatory activity in CD is based on clinical indexes,mainly the Crohn's Disease Activity Index(CDAI),blood markers of inflammation such as CRP,ESR,and endoscopic findings.The clinical activity is more objective and comprehensive than CDAI or endoscopic findings.Formerly,many studies about CTE diagnose the activity of CD were presented,but the relationships between the CTE findings of bowel inflammatory activity,and clinical and serum biochemical markers of inflammation have not yet been thoroughly investigated.They studied the CTE signs separately,and used CDAI as gold standard,which is subjectively designed and often unreliable.In our study,the CTE signs were observed and semi-quantitatively calculated by CTE score,and the gold standard was clinical activity,which is based on CDAI,blood markers of inflammation CRP and ESR,endoscopic findings.Then we assessed the CTE score diagnostic efficacy and calculated the diagnostic cut-off point for the activity and remissive of CD.Purpose:To discuss the diagnostic value of dual sources CTE score in activity for CD by ROC curve.Method:We retrospectively reviewed 131 CD inpatients from the Department of Gastroenterology in Nanfang Hospital,between June 2011 and February 2015.Clinical data included history,physical exam,laboratory tests and endoscopy.Clinical data was acquired one week before CTE,and the Montreal classification was made.131 patients with CD were confirmed by surgery,pathology retrospectively analyzed.Imaging findings of active and remissive were observed and semi-quantitatively calculated by CTE score.The CTE score was based on six signs,the thickening of the bowels,the mucous enhancement of the bowel walls,the stricture of the bowels,the comb sign,the enlarged mesenteric lymph nodes,hepatic perfusion disorder in arterial phase,fistulas,ulcers or abscess.The clinical activity based on CDAI,biomarkers,endoscopy findings or follow up was treated as gold standard,active as 1,remission as 0,and the variables was CTE score.Then we assessed the diagnostic efficacy of CTE score and calculated the diagnostic cut-off point for the activity of CD using ROC curve.Data were analyzed using the SPSS software for windows version 13.0.Data were presented as mean ± standard deviation(SD)or number(%).A P value of less than 0.05 was considered statistically significant.Results:The study population consisted of 131 patients(84 male;median age 32.05 years;range 13-72 years)with CD.13 patients(9.9%)were in clinical remission,and 118 patients(90.1%)were active disease.According to the Montreal classification,CD patients presented the following disease location:L1,28.2%;L2,6.9%;L3,51.9%;L1+L4,6.9%;and L3+L4,6.1%.45.0%had nonstricturing and nonpenetrating disease,32.1%had stricture disease,9.2%had penetrating disease,13.7%had both stricturing and penetrating disease.37 patients(28.2%)had perianal involvement.The area under ROC curve(AUC)of CTE score was 0.868(P=0.000),95%CI(0.786-0.951),the cut-off point,sensitivity specificity,and the mistake diagnose rate of the CTE score for diagnosing activity of CD were 6 points,78.2%,84.6%,15.4%,respectively.Conclusion:CTE score is effective in differentiating active and remissive Crohn's disease.The diagnose accordance rate with clinical diagnosis are strong.