Nearly three-quarters of patients with Crohn's disease have small bowel involvement and 80% of them will have complications that will require a surgical procedure, usually an ileocolonic resection with ileocolonic anastomosis. The rate of recurrence at the anastomosis site and in the ileum after surgery, whether symptomatic or not, is high, at least 60% in one year and 80% within three years. The gold standard for monitoring being ileocolonoscopy, endoscopic surveillance is recommended in these patients, once between 6 to 12 months after surgery and then every 2 years.

The MRI enterography is a validated technique for the assessment of small bowel Crohn's disease. The enterography MRI is a validated technique for the assessment of small bowel Crohn's disease. The MRI enteroclysis was evaluated in two studies compared to endoscopy, with excellent performance in terms of recurrence detection sensitivity and suggested as an alternative to it to avoid an invasive procedure repeated in these patients. The MRI enterography (without enteroclysis) does not provide as good distension of the bowel loops as MRI enteroclysis because it relies on the principle of oral ingestion prior to the examination of large amounts of liquid. However, it is much better tolerated by the patient, does not involve radiation that exists with enteroclysis, is much simpler to use and requires no special equipment to magnetic fields.

Determine the diagnostic performances of MRI enterography for the diagnosis of recurrence at the anastomosis site and in the ileum in patients with Crohn's disease who have had ileocolonic resection.

Assess the value of diffusion sequences of MRI enterography for the diagnosis of recurrence at the anastomosis site and in the ileum in patients with Crohn's disease who have had ileocolonic resection.

Inclusion Criteria:

• patients with Crohn's disease
• patients with ileocolonic resection more than 6 months ago and less than 4 years ago
• patients with indication of ileocolonoscopy
• patient consenting to participate to the study
• patient enrolled in the national healthcare insurance program
• patient older than 18 years

Exclusion Criteria:

• patients with contraindications for MRI