Published online Oct 21, 2020. doi: 10.3748/wjg.v26.i39.6057
Peer-review started: June 19, 2020
First decision: July 28, 2020
Revised: August 6, 2020
Accepted: September 12, 2020
Article in press: September 12, 2020
Published online: October 21, 2020
Crohn’s disease (CD) is a chronic inflammatory bowel disease which usually involves the terminal ileum. Clinically, it is important to evaluate accurately and noninvasively the activity of terminal ileum CD in order to make a precise treatment plan. However, current evaluation methods have their inherent disadvantages. Specifically, the Crohn’s Disease Activity Index (CDAI) is subjective, Crohn’s Disease Endoscopic Index of Severity (CDEIS) is invasive, and Magnetic Resonance Index of Activity (MaRIA) is complex.
The activity of terminal ileum CD is associated with the microcirculation of involved bowel walls. During the process of CD, blood perfusion and permeability increase and water diffusion will be restricted. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) can reflect perfusion and permeability of bowel walls by providing microcirculation information. As such, we hypothesize that DCE-MRI and DWI parameters can assess terminal ileum CD, thereby providing an opportunity to stage CD activity.
The parameters of DCE-MRI, based on the two-compartment Tofts model (TCM), and apparent diffusion coefficient (ADC), based on DWI, allow for the evaluation of perfusion and permeability in bowel walls. Few studies have analyzed the diagnostic performance of the combination of DCE-MRI and DWI in staging CD activity.
The purpose of this study was to investigate the performance of DCE-MRI and DWI as non-invasive methods in staging CD activity with CDAI and CDEIS as references.
Forty-eight patients with CD were analyzed retrospectively. According to the CDAI and CDEIS values, the patients were divided into the remission group (CDAI < 151, CDEIS < 3), mild group (CDAI 151-219, CDEIS 3-8), and moderate-severe group (CDAI > 219, CDEIS > 8). Ktrans, Kep, and Ve were calculated from DCE-MRI and ADC was obtained from DWI. MaRIA was calculated from magnetic resonance enterography. The parameters were compared between normal ileal loop (NIL) and inflamed terminal ileum (ITI). Correlations between these parameters, MaRIA with CDAI, CDEIS were examined. Receiver operating characteristic curve analyses were used to evaluate the performance of these parameters in staging CD activity.
In the present study, the results showed that higher Ktrans (0.07 ± 0.04 vs 0.01 ± 0.01), Kep (0.24 ± 0.11 vs 0.15 ± 0.05) and Ve (0.27 ± 0.07 vs 0.08 ± 0.03) but lower ADC (1.41 ± 0.26 vs 2.41 ± 0.30) values were displayed in the ITI than in the NIL (all P < 0.001). The parameters of DCE-MRI and MaRIA increased in CD progression, whereas the ADC decreased. The Ktrans, Kep, Ve and MaRIA showed positive correlations with the CDAI (r = 0.866 for Ktrans, 0.870 for Kep, 0.858 for Ve, 0.890 for MaRIA, all P < 0.001) and CDEIS (r = 0.563 for Ktrans, 0.567 for Kep, 0.571 for Ve, 0.842 for MaRIA, all P < 0.001), while the ADC showed negative correlations with the CDAI (r = -0.857, P < 0.001) and CDEIS (r = -0.536, P < 0.001). The areas under the curve (AUC) for the individual values ranged from 0.68 to 0.91 for differentiating inactive CD (CD remission) from active CD (mild to severe CD) and MaRIA had the higher AUC of 0.91. The AUC when combining the Ktrans, Kep and Ve was 0.80, while the AUC when combining DCE-MRI parameters and ADC was the highest (AUC = 0.95).
DCE-MRI and DWI are non-invasive methods with good performances in staging the activity of terminal ileum CD. When they were used in combination, the value was greater, which can supplement clinical diagnosis and monitoring.
DCE-MRI and DWI are valuable tools in staging CD with CDAI and CDEIS as the references. The correlation of the DCE-MRI and DWI parameters between pathological activity status of CD, and the performance of DCE-MRI and DWI in monitoring the treatment effect of CD should be explored in the future.