State of the Art MR Enterography Technique

Abstract

Magnetic resonance enterography (MRE) is a well-established imaging technique that is commonly used for evaluating bowel disease. While MRE can be used to assess a number of bowel conditions, the most common reason to perform MRE is for the diagnosis, surveillance and detection of complications of inflammatory bowel disease (IBD) (Table 1) (3-10). MRE has several significant advantages over CT enterography (CTE) and traditional barium-based fluoroscopic exams (i.e. small bowel series and enteroclysis) in evaluating IBD. MRE does not use ionizing radiation which is important for IBD patients, many of which present earlier in life and may require multiple imaging exams during their lifetime to monitor treatment (3, 4, 6-12). MRE's higher contrast resolution and multiphasic post contrast sequences compared to CTE makes MRE more sensitive in identifying bowel wall hyperemia and fibrosis and able to provide insight into the severity of small bowel inflammation (4). MRE also offers small bowel motility evaluation with "cine" sequences, a feature not available with CTE, which can help identify bowel inflammation, strictures, adhesions and small bowel masses (4,9,12,13). Finally, compared to CTE, MRE's higher contrast resolution provides better evaluation of the perianal region to identify perianal fistulas, which can occur in up to 25% of Crohn disease patients, along with possible associated abscesses (4). Table 1: Indications for MR Enterography MR Enterography IndicationsDiagnosis of IBD-evaluate disease activity, extent and distribution Follow up known IBD-evaluate disease activity and treatment response Evaluating possible IBD-related complications such as stricture, obstruction or penetrating disease (e.g. fistula, sinus tract or inflammatory mass) Small bowel masses Non-IBD enteritis (e.g. infection, vasculitis or treatment-related enteritis)

Bowel Wall Visualization Using MR Enterography in Relationship to Bowel Lumen Contents and Patient Demographics

“…One may further argue that MRE focuses on small bowel, and so optimization of colonic image quality is not required because the colon is not the target organ of evaluation. However, our findings suggest that colonic contents frequently degrade MRE images, which may be of concern for patients undergoing MRE have concern for IBD which affects mainly the colon 13 . Furthermore, Crohn's disease is known to affect the colon in approximately 26% of patients and in up to 56% of pediatric patients with penetrating disease 14 .…”

“…However, our findings suggest that colonic contents frequently degrade MRE images, which may be of concern for patients undergoing MRE have concern for IBD which affects mainly the colon. 13 Furthermore, Crohn's disease is known to affect the colon in approximately 26% of patients and in up to 56% of pediatric patients with penetrating disease. 14 As such, our findings suggest that further study is warranted to assess methods to minimize confusing colonic contents prior to MRE.…”

Editorial for “Bowel Wall Visualization Using MR Enterography in Relationship to Bowel Lumen Contents and Patient Demographics”

“…This may be of concern for patients undergoing MRE who have IBD, which primarily affects the colon. 8 Zhang et al 7 also reported that air-containing bowel in the colon compromised the bowel wall visualization in small bowel regions, particularly in children, which is contrary to the findings from Sinha et al 6 Moreover, Crohn's disease affects the colon of 56% of pediatric patients compared to 23% of adult patients with penetrating disease. 9 Thus, to minimize image misinterpretations based on colon content, Zhang et al suggest that bowel cleansing may be appropriate prior to MRE for patients where colonic involvement might be of concern.…”

“…Their findings suggest that the contents of the colon led to poor bowel wall enhancement visualization using MRE, more frequently in the colon. This may be of concern for patients undergoing MRE who have IBD, which primarily affects the colon 8 . Zhang et al 7 also reported that air‐containing bowel in the colon compromised the bowel wall visualization in small bowel regions, particularly in children, which is contrary to the findings from Sinha et al 6 Moreover, Crohn's disease affects the colon of 56% of pediatric patients compared to 23% of adult patients with penetrating disease 9 .…”

Simplified Magnetic Resonance Index of Activity Is Useful for Terminal Ileal but not Colonic Disease in Pediatric Crohn Disease

“…In addition, it can detect the complications of CD, and typically does not require anesthesia in children over 5 years of age (13).…”