MRI of Inflammatory Bowel Disease.

O ver the past decade, magnetic resonance enterography (MRE) has become a reliable and widely used imaging technique for evaluation of the small bowel in patients with inflammatory bowel disease (IBD), particularly Crohn disease. MRE’s multiplanar pulse sequences and high soft tissue contrast resolution provide optimal depiction of bowel wall and mesenteric inflammation, possible associated complications, and treatment response, while potentially determining the severity of intestinal inflammation better than any other imaging technique. MRE’s lack of ionizing radiation is ideal for patients with Crohn disease, many of which present at a relatively young age and may require multiple imaging examinations during their lifetime. MRE also has the unique feature of small bowel motility evaluation which can be helpful in identifying small bowel inflammation, strictures, adhesions, and masses. Finally, MRE can provide adequate evaluation of the perianal region to identify fistulas and abscesses that may require treatment or may indicate that more detailed high-resolution perianal MRI should be performed. In this special issue of Topics in Magnetic Resonance Imaging, ‘‘Magnetic Resonance Imaging of Inflammatory Bowel Disease,’’ we highlight the current and emerging MRI issues pertaining to diagnosing, characterizing, and managing IBD and the potential associated complications. The 6 manuscripts in this issue, presented by multiple Crohn disease experts, including 20 Society of Abdominal Radiology Crohn Disease Disease-Focused Panel members, provide a thorough review of a wide range of cutting-edge topics in this important field. Dr. Manjil Chatterji and colleagues provide a state-of-the-art review of the proper technique for performing MRE, including pediatric considerations. This includes a thorough review of intravenous and enteric contrast agents as well as the most commonly administered antiperistaltic agents both within and outside of the United States. Finally, the recommended and optional MRE pulse sequences and an alternative ‘‘Time-Efficient MRE Protocol’’ that is used at the Mayo Clinic are presented. Dr. David Grand and colleagues provide an in-depth discussion of qualitative and quantitative evaluation of small bowel inflammation. Their review includes discussions of the imaging findings associated with small bowel inflammation and a description of the most commonly used MREbased scoring systems along with their strengths and limitations. Dr.