The assessment of digestive inflammation and disease activity in paediatrics Crohn's disease (CD) is currently based on anamnestic, clinical and paraclinical elements such as the paediatric CD activity index (wPCDAI) , faecal calprotectin measuring or digestive endoscopy. Infrared thermal imaging is based on capturing electromagnetic waves, on a specific Wavelength, emitted by the human body surface and representing local thermic-metabolic activity. It concern metabolic activity in digestive inflammations. Infrared imaging is a non-invasive, contactless, stressless technique that assess the variations in skin surface temperature of the patient's entire abdomen or more targeted areas in a single photography. This technique would be useful for determination of Crohn's disease activity, inflammation's degree and partial mapping of inflammatory lesions.

In a specific room with a patient lying, the investigators will determine the abdominal infrared radiation with a FLIR® thermal camera. This will be correlated with the measurement of the faecal calprotectin concentration and the composite CD activity index wPCDAI.

All measurements will be performed during the standard follow-up of Crohn disease. No additional follow will be necessary.

Inclusion Criteria:

• Patients diagnosed with CD according to the Porto criteria [6]
• Aged from 4 years to 17 years-old
• Follow-up at the Amiens Picardie University Hospital (CHU Amiens Picardie)
• Child's affirmative agreement and assent and permission of their parents to participate in research

Exclusion Criteria:

• Recent abdominal surgery
• Other Inflammatory bowel disease