Inclusion Criteria:  Adult Crohn's disease (age ≥ 18 years) Symptomatic with Crohn's disease activity index (CDAI)> 150 Presence of objective signs of inflammatory activity (fecal calprotectin> 250 AND sign of MRI activity) Requiring treatment with biotherapy according to the investigator Able to give informed consent to participate in research Affiliation to a Social Security scheme.  Exclusion Criteria:  Severe obstructive symptoms Uncontrolled intra-abdominal abscess Isolated anoperineal lesions Prevention of postoperative endoscopic recurrence Temporary or definitive ostomy Total colectomy Contraindication to MRI Pregnant or breastfeeding women Protected adults (curatorship, guardianship, saving justice) Refusal of participation