Diffusion-weighted magnetic resonance enterocolonography in predicting remission after anti-TNF induction therapy in Crohn's disease

Abstract

Background

Diffusion-weighted magnetic resonance entero-colonography (DW-MREC) with no rectal distension and with no bowel cleansing is accurate to assess inflammatory activity in ileocolonic Crohn's disease (CD).

Aim

To study DW-MREC parameters as predictors of remission (CDAI < 150 and CRP < 5 mg/L) after anti-TNF induction therapy.

Methods

Forty consecutive CD patients were prospectively and consecutively included. All the patients underwent DW-MREC with apparent diffusion coefficient (ADC) and MaRIA calculation before starting anti-TNF. Mean ADC was defined as the mean of the segmental ADC.

Results

Twenty patients (50.0%) experienced remission at W12. Low mean ADC (2.05 ± 0.22 vs 1.89 ± 0.25, p = 0.03) and high total MaRIA (39.2 ± 16.6 vs 51.7 ± 18.2, p = 0.03) were predictive of remission at W12. Using a ROC curve, we determined a mean ADC of 1.96 as predictive cut-off of remission at W12 (AUC = 0.703 [0.535–0.872]) with sensitivity, specificity, positive predictive value and negative predictive value of 70.0%, 65.0%, 66.7% and 68.4%, respectively. In multivariate analysis, mean ADC < 1.96 (OR = 4.87, 95% CI [1.04–22.64]) and total MaRIA > 42.5 (OR = 5.11, 95% CI [1.03–25.37]), reflecting high inflammatory activity, were predictive of remission at week 12.

Conclusions

DW-MREC using quantitative parameters i.e. ADC, is useful in detecting and assessing inflammatory activity but also to predict efficacy of anti-TNF induction therapy in CD.

Introduction

Crohn's disease (CD) is a chronic relapsing and remitting disorder that can involve the entire length of the digestive tract [1]. Although anti-TNF therapy is, to date, the most effective treatment in CD, almost one third of patients experienced primary failure [2], [3], [4], [5]. Regarding the potential side effects and the costs of biologics, determining predictors of anti-TNF efficacy remains a key point in clinical practice. Several studies trials reported potential clinical [6], [7], [8], [9], biological [10], [11] or genetic [10], [12], [13], [14] predictive factors for efficacy of anti-TNF induction therapy.

New therapeutic goals such as achieving mucosal healing [15], [16], [17] or preventing digestive damage [18], [19] have emerged in the era of biologics and require objective tools to evaluate disease activity. Although colonoscopy is to date the gold standard for assessing ileal and colonic disease activity, the need to repeat this procedure during the CD monitoring in daily practice, have led physicians to look for alternative non-invasive approaches. Thus, magnetic resonance imaging (MRI) has been increasingly used for the diagnosis and the monitoring of CD patients and is very effective to assess inflammation and therapeutic response [20], [21], [22]. Recently, Diffusion-Weighted Magnetic Resonance Entero-Colonography (DW-MREC) has shown high efficacy to assess inflammatory activity in the ileum using the Clermont score (=1.646 × bowel thickness − 1.321 × ADC + 5.613 × oedema + 8.306 × ulceration + 5.039) and in the colon/rectum using the apparent diffusion coefficient (ADC) which is the quantitative parameter of DW-MRI [23], [24], [25], [26].

We aimed to study DW-MREC parameters as predictors of remission defined as CDAI < 150 and CRP < 5 mg/L at week 12. Predictors of clinical response at week 12 (ΔCDAI ≥ 100) were investigated as secondary endpoint.