The purpose of this study is to investigate differences of the bowel wall thickness visible in conventional ultrasound and bowel perfusion using quantitative Contrast-Enhanced Ultrasound in patients with Crohn´s disease in comparison with healthy controls and patients with food allergy.

After being informed about the study and potential risks, all participants giving written consent will undergo conventional transabdominal ultrasound and Contrast-Enhanced Ultrasound of the bowel wall with measurement of the bowel wall thickness. In addition a continuous video sequence during Contrast-Enhanced Ultrasound is recorded and perfusion kinetics from the video clips are analyzed using a specific quantification software.

Inclusion Criteria:

• Age over 18
• Endoscopically and histologically confirmed active Crohn´s disease or
• Previously proven food allergy (double-blind or single-blind food challenge tests with placebo controls previously before the sonographic examination, increased blood and / or intestinal Immunoglobulin E levels, elevated methylhistamine values under provocation and with reproducible reactions during food challenge procedures) or
• Healthy individuals without abdominal complaints

Exclusion Criteria:

• Age under 18
• Intolerance of the ultrasound contrast agent SonoVue
• Refusal of participation in the study
• Pregnancy or breast-feeding

Tertiary-care university hospital, patients diagnosed and treated in the outpatient department for inflammatory and allergic bowel diseases