Role of Intestinal Ultrasound in the Management of Patients with Inflammatory Bowel Disease

Aranzazu Jauregui-Amezaga, Jordi Rimola, Aranzazu Jauregui-Amezaga, Jordi Rimola

Abstract

Intestinal ultrasound (IUS) has gained popularity as a first line technique for the diagnosis and monitoring of patients with inflammatory bowel diseases (IBD) due to its many advantages. It is a non-invasive imaging technique with non-ionizing radiation exposure. It can be easily performed not only by radiologists but also by trained gastroenterologists at outpatient clinics. In addition, the cost of IUS equipment is low when compared with other imaging techniques. IUS is an accurate technique to detect inflammatory lesions and complications in the bowel in patients with suspected or already known Crohn's disease (CD). Recent evidence indicates that IUS is a convenient and accurate technique to assess extension and activity in the colon in patients with ulcerative colitis (UC), and can be a non-invasive alternative to endoscopy. In patients with IBD, several non-specific pathological ultrasonographic signs can be identified: bowel wall thickening, alteration of the bowel wall echo-pattern, loss of bowel stratification, increased vascularization, decreased bowel peristalsis, fibro-fatty proliferation, enlarged lymph nodes, and/or abdominal free fluid. Considering the transmural CD inflammation, CD complications such as presence of strictures, fistulae, or abscesses can be detected. In patients with UC, where inflammation is limited to mucosa, luminal inflammatory ultrasonographic changes are similar to those of CD. As the technique is related to the operator's experience, adequate IUS training, performance in daily practice, and a generalized use of standardized parameters will help to increase its reproducibility.

Keywords: Crohn’s disease; IBD; IUS; bowel ultrasound; cross-sectional imaging; imaging; inflammatory bowel diseases; ulcerative colitis.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Bowel wall layers: The bowel wall layers are, from the bowel lumen: (a) the mucosal layer (hyperechoic), which is the interface between the mucosa and the bowel lumen; (b) the deep mucosa (hypoechoic), which has a variable thickness and represents the packed glandular tissue; (c) the submucosa (hyperechoic), which contains connective tissue with vessels, nerves and fat; (d) the muscularis propria (hypoechoic), with an inner circular muscle layer and an outer longitudinal muscle layer; and (e) the serosa (hyperechoic), which is the visceral peritoneum.
Figure 2
Figure 2
Measurement of bowel wall thickening and bowel wall stratification: Bowel wall thickening is the most important IUS parameter in IBD patients. The most commonly used cut-off value is 3 mm. The bowel wall stratification can be focally or extensively disrupted or lost due to inflammation. (a) Bowel wall thickening with preserved layer stratification. (b) Bowel wall thickening with loss of stratification.
Figure 2
Figure 2
Measurement of bowel wall thickening and bowel wall stratification: Bowel wall thickening is the most important IUS parameter in IBD patients. The most commonly used cut-off value is 3 mm. The bowel wall stratification can be focally or extensively disrupted or lost due to inflammation. (a) Bowel wall thickening with preserved layer stratification. (b) Bowel wall thickening with loss of stratification.
Figure 3
Figure 3
Bowel vascularization: Bowel wall vascularization can be measured by color or power Doppler US. The Limberg score is widely used for the assessment of mural and extramural flow. In the picture, an increased bowel vascularization (Limberg score grade 3) can be visualized in the inflamed bowel.
Figure 4
Figure 4
Extraintestinal ultrasonographic findings. (a) Presence of free fluid. (b) Detection of a lymph node and presence of fibro-fatty proliferation (echogenic peri-enteric fat).
Figure 5
Figure 5
Detection of complications: stricture with pre-stenotic dilation: Strictures are characterized by a wall thickening with a narrowed lumen, with or without a dilatation of the proximal loop (pre-stenotic dilatation).
Figure 6
Figure 6
Detection of complications: fistulae and abscesses: (a) The fistulae are seen as hypoechoic peri-intestinal areas with a diameter <2 cm with or without internal gaseous artifacts. (b) Abdominal abscesses are seen as hypo-anechoic lesions containing fluid and gaseous artifacts, posterior enhancement, irregular margins sometimes within fibro-fatty proliferation, without vascular signals in color Doppler.
Figure 6
Figure 6
Detection of complications: fistulae and abscesses: (a) The fistulae are seen as hypoechoic peri-intestinal areas with a diameter <2 cm with or without internal gaseous artifacts. (b) Abdominal abscesses are seen as hypo-anechoic lesions containing fluid and gaseous artifacts, posterior enhancement, irregular margins sometimes within fibro-fatty proliferation, without vascular signals in color Doppler.

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