Small Bowel Magnetic Resonance Imaging for Inflammatory Bowel Disease

Abstract

The presented concept of hydro-magnetic resonance imaging (MRI) using a 2.5% mannitol solution as an orally applicable intraluminal contrast agent is a meaningful, reproducible, and reliable imaging method for the depiction of the small bowel. Especially in patients with Crohn's disease, hydro-MRI is the imaging method of first choice because hydro-MRI offers the advantage of a superior depiction of the inflamed bowel wall and the extramural complications of this disease without radiation exposure. In addition, hydro-MRI allows for a reliable assessment of the inflammatory activity, especially for the differentiation between an active and an inactive (scarred) stenosis. In particular, the mural enhancement, the length as well as the wall thickness of inflamed bowel segments, are considered to be significant MR parameters for the determination of the activity of Crohn's disease. Hydro-MRI of the colon is suitable for the depiction of pathologic changes in ulcerative colitis, but in contrast to Crohn's disease, the assessment of disease activity by hydro-MRI is unreliable in ulcerative colitis, probably because of the low spatial resolution (mucositis in ulcerative colitis vs. transmural inflammation in Crohn's disease). Hydro-MRI does not allow a reliable classification of inflammatory bowel diseases, but in ambiguous cases, hydro-MRI may provide helpful information for the differentiation of Crohn's disease and ulcerative colitis. There are no data of larger patient groups published regarding MR findings in inflammatory bowel diseases besides Crohn's disease and ulcerative colitis, but hydro-MRI is a promising imaging tool for these entities, which should be assessed in additional studies.

New Diagnostic Avenues in Inflammatory Bowel Diseases

“…But there are more and more indications that an exclusively oral application of the contrast media gives adequate diagnostic quality [34,35]. To achieve an adequate bowel distension with oral contrast application, substances such as mannitol [36] or methylcellulosis [37] have to be added to the contrast media. Currently, several intraluminal contrast media (table 1) are used for small bowel MRI.…”

New serological biomarkers of inflammatory bowel disease

“…Application of IBD biomarkers is cheaper, less laborious, less invasive, and more objective compared to the endoscopy/biopsybased approach [1] . Current IBD biomarkers include serological, fecal and genetically predisposed gene polymorphisms [2][3][4][5] with imaging technologies such as optical, ultrasound, magnetic resonance imaging (MRI), X-ray, computer tomography (CT), position emission tomography (PET), single photon emission computed tomography (SPECT) [6][7][8][9] . Among those, fecal [10,11] and serological biomarkers, including systemic level of specific antibodies and other serum proteins [4,[12][13][14] , have been most widely explored and/or used in clinical studies.…”

MRI of the small bowel: can sufficient bowel distension be achieved with small volumes of oral contrast?

“…However, water is absorbed quickly and its oral administration often results in an insufficient distension of the ileum [2][3][4]. Oral solutions containing different additives, including mannitol [5], sorbitol [6], polyethylene glycol [7] or ispaghula [8], have been proposed in order to decrease or slow down its intestinal reabsorption.…”