Searching for secondary signs of regional inflammation, such as increased mesenteric vascularity ("comb sign") or perienteric fluid or enhancement can prove particularly fruitful in identifying regions of active inflammation (Figure 5).
Perienteric and interloop abscesses may form, but may be difficult to detect on MR, and thorough investigation of bowel loops and the mesentery in all available planes should be undertaken.
29, 43, 44) Although generally submucosal based, a majority of tumors extend into the muscularis propria and in rare cases extend transmurally into the perienteric
connective tissue or even metastasize to regional lymph nodes.
Other findings, such as the Comb sign (engorgement of the vasa recta), fibrofatty proliferation, and stranding in the perienteric
fat also indicate active inflammation.