Diagnostic Performances of Diffusion-Weighted Magnetic Resonance Imaging in the Evaluation of Fibrosis and Post-Operative Endoscopic Recurrence in Crohn’s Disease

Abstract

Background: Diffusion-weighted represents a new application of magnetic resonance imaging (DW-MRI) to assess inflammatory activity in Crohn's disease. ADC is a quantitative parameter of this phenomenon. We aimed to verify the correlation between DWI findings both with pathological evaluation of fibrosis in surgical specimen both with endoscopic recurrence.Methods: 31 pts undergoing ileocolonic resection for CD were submitted to DW-MRI. Conventional MRI findings of terminal or neo-terminal ileum were recorded together with a semiquantitative evaluation of DWI signal intensity and with ADC calculation. For the first aim, Acute Inflammatory (AIS) and Fibrostenosis score was correlated to ADC values of matched ileo-cecal segment. ROC curves analysis was used to find out an ADC cut-off value able to distinguish "low and high grade" severity of post-operative recurrence. Results:Comparison of DWI findings with surgical specimens pathologic evaluation showed a very good correlation, inverse and statistically significant, between ADC and AIS total (r=-0.90, p=0.013). The mean ADC value of the 5 pts with fibrosis was not statistically different from the 5 pts without. The comparison between ADC and Rutgeerts'score showed a good correlation, inverse and statistically significant (rho= -0.73, P=0.002). ROC curves analysis highlighted that a value of ADC ≤ 1.82 x10 -3 mm 2 /s could predict a severe recurrence (Rs >i2) with a sensitivity of 88.9% and a specificity of 83.3%. Conclusion:This study showed the ability of DWI sequences to provide quantitative measures of inflammation, allowing a more objective assessment of CD. Further studies should clarify whether ADC evaluation could predict the presence of fibrosis in surgical specimens.