MR Enterography
Jordi Rimola1

1Radiology, Hospital Clínic Barcelona

Synopsis

In this lecture we are going to discuss the key signs for detecting and grading active inflammation and characterizing complications, in particular strictures. We also highlight the current limitations of the technique and potential ways to overcome them.

Highlights in this session:

  • MRE provides a comprehensive, objective assessment of disease activity and complications
  • Magnetic Resonance Enterography (MRE) has a pivotal role in the management of patients with Crohn’s disease
  • Functional sequences on MRE may potentially improve the detection and characterization of lesions in the bowel

Learning objectives

  • To become familiar with the semiology of Crohn’s disease that can be seen on MRE
  • To learn about the impact of MRE on management options
  • To discuss the potentialities and limitations of new MR sequences to characterize lesions on Crohn’s disease

Summary of the session

Magnetic Resonance Enterography (MRE) uses a combination of magnetic resonance imaging (MRI) techniques that characterize morphological (e.g. bowel wall thickening, stricturing, ulceration), pathophysiological (e.g. hyper-perfusion, edema, comb sign), penetrating complications, and other features of Crohn’s Disease (CD). Objective MRE-based scores of inflammatory disease activity in CD have been developed and reported to be highly correlated with scores of mucosal inflammation in the colon and terminal ileum determined by ileocolonoscopy (ICS) or other endoscopic techniques. Compared to ICS, MRE exams can provide a more comprehensive assessment not only of mucosal inflammation but also of transmural and penetrating complications of disease activity in the small intestine and colon. MRE does not use any ionizing radiation and therefore facilitates acquisition of serial scans (i.e. during a course of treatment). As a result, MRE is becoming the first-line modality for the evaluation of suspected or known inflammatory bowel disease that, by far, represents the main clinical use of this technique. Also, MRE is having an emerging role in clinical trial setting, for assessing the efficacy of novel therapies as well as ensuring appropriate selection of patients for inclusion into clinical trials. Crohn's disease (CD) is a chronic inflammatory disorder that can affect any segment of the digestive tract and is characterized by periods of clinical remission alternating with periods of recurrence. The assessment of active disease and grading the severity of lesions is key for the proper management of the disease. The routine MRE includes in most cases the use of gadolinium-based intravenous contrast agents. Concerns on brain retention of these contrast agents have raised the need of limiting its use. Novel sequences such as diffusion-weighted imaging have been postulated as alternative to gadolinium-enhanced sequences but limitations on its use in clinical practice and in research may limit its utility. On the other hand, repeated flares of active inflammation may progress to fibrosis with intestinal strictures and obstruction. On histopathology, inflammation and fibrosis are intimately intertwined and coexist in CD strictures to varying degrees. Intestinal fibrosis is a consequence of chronic inflammation characterized by excessive extracellular matrix protein deposition. Clinically, inflammation predominant strictures could be relieved by anti-inflammatory medical treatment whereas fibrosis predominant strictures require endoscopic or surgical treatment. Hence, precisely defining the type of CD strictures and quantitatively detecting intestinal fibrosis is crucial for appropriate treatment.

Acknowledgements

No acknowledgement found.

References

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Proc. Intl. Soc. Mag. Reson. Med. 26 (2018)