Objective: Assessment of disease extension and activity is crucial to guide treatment in Crohn’s disease. The objective of the current cross-sectional study was to determine the accuracy of MR for this assessment. Design: 50 patients with clinically active (n = 35) or inactive (n = 15) Crohn’s disease underwent ileocolonoscopy (reference standard) and MR. T2-weighted and precontrast and postcontrast-enhanced T1-weighted sequences were acquired. Endoscopic activity was evaluated by CDEIS (Crohn’s Disease Endoscopic Index of Severity); in addition endoscopic lesions were classified as absent, mild (inflammation without ulcers) or severe (presence of ulceration). Results: The comparison of intestinal segments with absent, mild and severe inflammation demonstrated a progressive and significant (p<0.001) increase in the following MR parameters: wall thickness, postcontrast wall signal intensity, relative contrast enhancement, presence of oedema, ulcers, pseudopolyps and lymph node enlargement. Independent predictors for CDEIS in a segment were wall thickness (p = 0.007), relative contrast enhancement (p = 0.01), presence of oedema (p = 0.02) and presence of ulcers at MR (p = 0.003). There was a significant correlation (r = 0.82, p<0.001) between the CDEIS of the segment and the MR index calculated according to the logistic regression analysis coefficients. The MR index had a high accuracy for the detection of disease activity (area under the receiver operating characteristic (ROC) curve 0.891, sensitivity 0.81, specificity 0.89) and for the detection of ulcerative lesions (area under the ROC curve 0.978, sensitivity 0.95, specificity 0.91) in the colon and terminal ileum. Conclusion: The accuracy of MR for detecting disease activity and assessing severity brings about the possibility of using MR as an alternative to endoscopy in the evaluation of ileocolonic Crohn’s disease.

Measurement of the component of fibrosis in Crohn's disease (CD) may have important therapeutic implications. The aim of this study was to characterize the Magnetic Resonance Imaging (MRI) findings that are differentially associated with the presence of fibrosis and those associated with inflammatory activity, using the pathological analysis of surgically resected intestinal lesions as reference standard. MRI studies with identical imaging protocol of 41 CD patients who underwent elective bowel resection within 4 months before surgery were reviewed. MRI evaluated wall thickening, edema, ulcers, signal intensity at submucosa at 70 s and 7 min after gadolinium injection, stenosis, and pattern of enhancement in each phase of the dynamic study and changes on this pattern over time. Pathological inflammatory and fibrosis scores were classified into three grades of severity. In all, 44 segments from 41 patients were analyzed. The pathological intensity of inflammation was associated with the following MRI parameters: hypersignal on T2 (P=0.02), mucosal enhancement (P=0.03), ulcerations (P=0.01), and blurred margins (P=0.05). The degree of fibrosis correlated with the percentage of enhancement gain (P<0.01), the pattern of enhancement at 7 min (P<0.01), and the presence of stenosis (P=0.05). Using percentage of enhancement gain, MRI is able to discriminate between mild-moderate and severe fibrosis deposition with a sensitivity of 0.94 and a specificity of 0.89. MRI is accurate for detecting the presence of severe fibrosis in CD lesions on the basis of the enhancement pattern.

Background. The main objective was to identify risk factors for extent progression in distal ulcerative colitis. The secondary objective was to determine clinic