Diagnostic value of magnetized transfer imaging and diffusion-weighted imaging in the evaluation of bowel wall in Crohn disease

Objective: To explore the diagnostic value of magnetization transfer imaging (MTI) and DWI for detecting intestinal wall property of crohn's disease (CD). Methods: Forty four patients with CD were prospectively enrolled in the study, and MR enterography (MRE), MTI and DWI were performed. According to MRE findings, patients were divided into three subgroups: acute inflammatory group, chronic fibrotic group and combined inflammatory with fibrotic group. Intestinal wall T₂WI signal, magnetization transmisson rate (MTR) and ADC value were measured on MRE, MRI and DWI imagings, respectively. The differences of MTR and ADC among the three groups were analyzed by one-way ANOVA; the differences of T₂WI scores were analysed by Kruskal Wallis; the differences of MTR and ADC values between normal and pathological intestinal wall were analyzed by paired t test; ROC curve were used to evaluate the CD fibrosis and inflammation diagnostic efficiency of MTI ana DWI based on MRE signs. Results: Among the 44 cases, 11 cases were in the acute inflammatory group, 18 cases were in the chronic fibrotic group and other 15 cases were in the combination group. The T₂WI score, MTR and ADC among the three groups showed significant differences (all P<0.01).The mean MTR and ADC of pathological intestinal wall of the 44 cases were (40.77±6.05)% and (1.04±0.18)× 10^-3mm²/s, and the adjacent normal bowel were (21.75±4.17)% and (1.97 ± 0.23) × 10^-3mm²/s, respectively. Moreover, the difference of the above values showed significant differences (t=19.12, -21.80 respectively, all P<0.01). There was a negative correlation between MTR and T₂WI score (r=-0.71,P<0.01). While ADC value was positively correlated with T₂WI score (r=0.80, P< 0.01). Using ROC curve analysis to differentiate the CD fibrosis from acute inflammation, the area under the curve (AUC) of MTR and ADC were 0.97 and 0.96,respectively. Conclusions: Both MTI and DWI can be used to assess the properties of intestinal wall, which has the same diagnostic efficacy to identify the acute inflammation and fibrosis.