[Objective]To explore the efficacy of T2* mapping for evaluating inflammatory activity in the patients with Crohn disease(CD).[Methods]A total of 98 CD patients underwent MR enterographywith T2*WI. T2* values were measured by put-ting regions of interest on the thickening bowel wall on T2*mapping. The activity of bowel segment was scored by magnetic resonance index of activity(MaRIA),to analyze the relationship between T2*values with CD activity.[Results]A total of 160 bowel segments were evaluated and includedinactive(MaRIA<7,n=26),mild(7≤MaRIA<11,n=23),and moderately-severe(MaRIA≥11, n = 111)active lesions. The differences in T2* values amongthese three groups were significant(all P < 0.05). T2* values of 160 bowel segments correlatedclosely withMaRIA(r=0.743,P<0.05). High accuracy of T2*values was shown for differentiating inac-tive from active CD(AUC=0.877)anddifferentiating inactive-mild from moderate-severe CD(AUC=0.848). The threshold T2*value of 20 ms allowed differentiation of mild from moderate-severe CD with74.5%sensitivity and 84%specificity.[Conclusions]T2*values, as thequantitative indexof T2*mapping,correlate well with CD activity and showsatisfiedefficacy for diagnosing inflammatoryactivity.

Objective To determine the correlation between intravoxel incoherent motion (IVIM) parameters and both histologic inflammatory and fibrotic grades of Crohn disease (CD) in adults. Methods Prospectively, 17 patients (77 lesions) with a clinical and pathological diagnosis of CD in the first affiliated hospital of sun yat-sen university from July 2015 to June 2016 underwent MRE 15 days before surgery. All patients underwent T2WI, IVIM and enhanced MRI and calculated IVIM parameters include diffusion-related coefficient (D), perfusion-related coefficient (D*) and perfusion-related fraction (f). Histological intestinal inflammation and fibrosis was scored using the surgical histopathology as reference standard and further divided into mild-moderate (score 1 to 2) and severe (score 3 to 4) groups. Intestinal microvessel density (MVD) were also analyzed. Differences in IVIM parameters among different histological inflammation and fibrosis grades were assessed with the Kruskal-Wallis test. The Wilcoxon test was used for assessing differences in f between mild-moderate and severe fibrosis. The bivariate correlations between IVIM parameters and histological inflammation and fibrosis grades were analyzed using partial correlation . The bivariate correlations between IVIM parameters and MVD were analyzed using Spearman rank correlation. The areas under the receiver operating characteristics curves (AUROC) were analyzed to evaluate the efficacy for distinguishing severe from mild-moderate fibrosis. Results Of 77 surgical specimens, there were 41 mild-moderate and 36 severe inflammatory bowel segments, along with 22 mild-moderate and 55 severe fibrotic bowel segments. Positive correlation was shown between histologic inflammatory and fibrotic scores (r=0.592, P<0.01). MVD (42.7 ± 39.9)/HP presented weak positive correlation with histologic inflammatory scores (r=0.332, P=0.003) while no correlation with histologic fibrotic scores (r=0.129, P=0.262) was presented. Neither the D nor the D* values significantly correlated with histologic inflammation or fibrosis (P>0.05) while the f value significantly correlated with both histologic inflammation and fibrosis (P<0.05). Significant correlation was present between the f value and histologic inflammatory and fibrotic scores, respectively (r=-0.280, -0.520;P<0.05). There was significant difference in the f value between mild-moderate and severe fibrosis(Z=-5.255,P<0.01). The AUROC for the f value to distinguish between patients with mild-moderate fibrosis and severe fibrosis were 0.885. Using a threshold fractional perfusion of 0.33, the sensitivity and specificity values were 95.5％ and 81.8％, respectively. No correlation between f, D and D*value with histologic fibrotic scores (r=0.129, P=0.262) was presented. Conclusion The f value derived from IVIM could help to evaluate the severity of intestinal inflammation and fibrosis CD in adults.

Objective To assess the diagnostic value of magnetization transfer MRI (MTI) for bowel inflammation and fibrosis in humans with Crohn disease (CD). Methods From July 2014 through April 2017, 31 patients with a confirmed diagnosis of CD were prospectively recruited from the First Affiliated Hospital of Sun Yat Sen University. They were scheduled for elective surgery due to bowel obstruction and other complications, and underwent preoperative MR enterography (MRE) and MTI within 15 days of surgery. All cases had available intestinal specimens identified on MRE and resected bowel segments for region by region matching. All patients underwent breath hold conventional MRE and MTI examinations, and then the magnetization transfer ratios (MTRs) of pathological bowel segments were measured. Using region by region correlation between MTI and surgical specimen, the bowel segments were resected to stain with HE for evaluating bowel inflammation, Masson for bowel fibrosis, and typeⅠcollagen staining for the deposition of typeⅠcollagen within the bowel walls. The histologic sections from the most severe areas were scored as 0 (normal), 1 (mild), 2 (moderate) and 3 (severe). The correlations between MTR and histologic scores were analyzed by using Spearman rank correlation or partial correlation. The differences in MTR among different grades of bowel fibrosis were analyzed by one way ANOVA. The efficacy of MTR for predicting bowel fibrosis was evaluated by receiver operating characteristic curves analysis. The difference in MTRs between purely inflammatory bowel walls and mixed fibrotic and inflammatory bowel walls was analyzed by Student s t test. Results Sixty two resected bowel specimens from 31 patients including 9 purely inflammatory bowel walls and 53 mixed fibrotic and inflammatory bowel walls were obtained in this study. There were significant differences in MTR among non fibrotic [(21.45 ± 2.65)%], mildly [(30.88 ± 6.14)%], moderately [(35.14 ± 4.31)%] and severely [(35.14 ± 4.31)%] fibrotic walls (F=38.397,P<0.01). MTRs strongly correlated with fibrosis scores (r=0.681, P<0.01). High accuracy of MTRs was shown (curve under area=0.905, P<0.01) for differentiating moderately severely fibrotic from non fibrotic and mildly fibrotic bowel walls. Using MTR of 31.50% as a cutoff value, the sensitivity and specificity were 93.6% and 80.0%, respectively. The MTRs of purely inflammatory bowel walls [(21.45 ± 2.65)%] were significantly higher than that of mixed fibrotic and inflammatory [(36.28±5.21)%] bowel walls (t=-13.052,P<0.01). MTRs correlated with the scores of type Ⅰ collagen (r=0.325, P=0.044) but did not correlate with inflammation scores (r=-0.024, P=0.857). Conclusions MTI enables quantitative evaluation of bowel fibrosis in patients with CD and can be used to differentiate purely inflammatory CD from mixed fibrotic and inflammatory CD.