Effectiveness of MR Enterography for the Assessment of Small-Bowel Diseases beyond Crohn Disease

Abstract

The use of cross-sectional imaging techniques for the noninvasive evaluation of small-bowel disorders is increasing. The effectiveness of magnetic resonance (MR) enterography for the evaluation of Crohn disease, in particular, is well described in the literature. In addition, MR enterography has an evolving though less well documented role to play in the evaluation of other small-bowel diseases, including various benign and malignant neoplasms arising in isolation or in polyposis syndromes such as Peutz-Jeghers, inflammatory conditions such as vasculitis and treatment-induced enteritis, infectious processes, celiac disease, diverticular disease, systemic sclerosis, and bowel duplication. MR enterography may be useful also for the evaluation of intermittent and low-grade small-bowel obstructions. Advantages of MR imaging over computed tomography (CT) for enterographic evaluations include superb contrast resolution, lack of associated exposure to ionizing radiation, ability to acquire multiplanar primary image datasets, ability to acquire sequential image series over a long acquisition time, multiphasic imaging capability, and use of intravenous contrast media with better safety profiles. MR enterography also allows dynamic evaluations of small-bowel peristalsis and distensibility of areas of luminal narrowing and intraluminal masses by repeating sequences at different intervals after administering an additional amount of the oral contrast medium. Limitations of MR enterography in comparison with CT include higher cost, less availability, more variable image quality, and lower spatial resolution. The advantages and disadvantages of MR enterography performed with ingestion of the oral contrast medium relative to MR enteroclysis performed with infusion of the oral contrast medium through a nasoenteric tube are less certain.

Current MR-Enterography In The Diagnosis Of Crohn’s Disease, An Update.

“…20 mg intravenous(IV) Buscopan, Hyoscine-N-butyl bromide can be administered to prevent intestinal spasm and abdominal dyscomfort of the patients, 1 mg Glucagon subcutaneously or 0.3 mg IV Scopolamine can also be used as spasmolytic agents (4,5).Current MRE protocol is: Fat-saturated(FS) T2 weighted(W) sequences in axial and coronal planes, T2W gradient echo breath-hold sequence in axial plane, precontrast T1W-WATS and fat-saturated 3D-T1W gradient-echo sequence in coronal planes, post-contrast dynamic T1W-gradient echo sequences in axial and coronal planes (2,5,7,(10)(11)(12)(13).Post-contrast dynamic images are often obtained at arterial-portal and late venous phases. The all MRE acquisitions are about 20-25 min of duration per patient.All MR-Enterography procedure was performed at 1.5 T Magnet, Achievva HB, Philips,Netherland.. Diffusion-weighted imaging(DWI) and magnetization transfer imaging(MTI) are the new imaging sequences and techniques that can be performed for the accurate diagnosis of Crohn's disease (2,9,10).…”

“…The all MRE acquisitions are about 20-25 min of duration per patient.All MR-Enterography procedure was performed at 1.5 T Magnet, Achievva HB, Philips,Netherland.. Diffusion-weighted imaging(DWI) and magnetization transfer imaging(MTI) are the new imaging sequences and techniques that can be performed for the accurate diagnosis of Crohn's disease (2,9,10). In case of active inflammation, restricted diffusion on high-b-value is conducted at DWI in case of Crohn's disease, whereas infrequent for ulcerative colitis.…”

“…In case of active inflammation, restricted diffusion on high-b-value is conducted at DWI in case of Crohn's disease, whereas infrequent for ulcerative colitis. To my experience, DWI may play a collaborating role in the imaging of patients who can't tolerate OCA's or in patients in whom IV contrast agent use is contraindicated (5,9).MTI may reflect the enteric fibrosis and stricture development in Crohn's disease via transfer of energy from the free (Continued on page 14) water protons inside the lumen, to the macromolecules especially for the collagen fibers at the bowel wall (9)(10)(11)(12). Motility of the small intestine can be visualized by cine MRI via fast T2W images or true fast steady-state precession imaging, abnormal bowel motility and inflammatory activity in Crohn's disease can be shown, based on wall thickness, ulceration and T2 signal intensity (9,(11)(12)(13) (Figure 1a-1b).…”

“…Crohn's disease is a chronic inflammatory bowel disease with transmural invasion, causes damage to bowel wall with progression from inflammation to fibrosis over time (6,9,(12)(13)(14)(15)(16)(17).It is mostly seen in young adults between 15 -30 years of age and slightly predominant in females, can be seen in any part of bowel, but predominant in terminal ileum with invasion to ileoceccal valve, forms enteric abcesses and via fistulization, invades adjacent bowel loops and wall (2,6,7,10,13,14,18). It has three main subgroups: Ulcerative-fistulizing and stenosing types, ulcerations of hypertrofied ileum and ileoceccal valve are predominant in ulcerative form, entero-enteric and entero-colic fistulas are the characteristic findings of fistulising form and stenotic segments with skip lesions and dilated pre-obstructed segments are the pathognomonic presentations of stenosing form (6,11,14,(16)(17)(18)(19)(20).…”

Diagnostic value of MR enterography for the assessment of small-bowel diseases

“…MR enterografi yeni bir yöntemdir ve ince bağırsak lümenini, duvarını ve etrafındaki yapıları değerlendirebilir. MR enterografi ile yapılan çalışmalarda infeksiyon, tümör, polip, yapışıklık, vasküler malformasyon ve inflamatuvar bağırsak hastalıklarının (İBH) saptanmasında anlamlı sonuçlar elde edilmiştir [1][2][3]. Ayrıca süperpozisyon ve radyasyon maruziyetinin olmaması, yumuşak doku kontrastının yüksek olması, hamilelerde ve iyot alerjisi öyküsü olan hastalarda kullanılabilir olması da yeni bir yöntem olarak dikkatleri MR enterografiye çekmiştir.…”