[Modern MRI of the small bowell]

The radiological diagnostics of diseases of the small intestine have undergone a great change in the last two decades. Through rapid progress with new treatments and an increasing therapeutic focus on transmural healing, a complete evaluation of the gastrointestinal tract is now crucial.

With the introduction of endoscopy, gastrointestinal imaging with a relatively high radiation exposure had only limited applications. The development of cross-sectional imaging allowed a much broader radiological evaluation of abdominal diseases. Due to rapid investigation techniques, excellent soft tissue contrast and the distinct advantage of eliminating exposure to radiation, magnetic resonance imaging (MRI) of the gastrointestinal tract has gained increasing importance. With sufficient filling of the intestinal lumen, simultaneous imaging of all the intestinal wall layers, the perienteric structures and associated abdominal pathologies is now possible.

New MR sequences, such as diffusion-weighted sequences, dynamic contrast-enhanced sequences and MR fluoroscopy, enable the detection of morphological changes, with additional characterization of affected bowel loops as well as the assessment of functional pathologies with dynamic information about intestinal motility disturbances.

Recent guidelines of European radiological and gastroenterological organizations have confirmed the importance of cross-sectional imaging and particularly of MRI for diagnostics and follow-up in patients with Crohn's disease. Due to the possibility of assessment of all the layers of the intestinal wall and the presence of extramural complications, MRI has a significant impact on further therapeutic treatment in patients with inflammatory bowel disease.

Especially in patients with inflammatory bowel disease, MR enterography and MR enteroclysis should be the methods of choice for the evaluation of small bowel pathologies because of radiation issues and the great diagnostic value they provide. A variety of MR sequences has enabled not only the detection but also the characterization of pathological changes of the small intestine, which are vital for further treatment of these patients.