Small-Bowel Masses MRI imaging

An advantage of MR imaging over CT for the detection of small-bowel masses is the ability of MR imaging to generate images with different gradations of luminal contrast agents. Small-bowel masses have varying enhancement patterns. At CT, hyperenhancing masses are well depicted when neutral enteric contrast material is administered; however, some masses are isoattenuating relative to the bowel wall, and in areas with suboptimal distention, such masses may be difficult to detect. The alternative use of a positive enteric contrast agent at CT may mask the enhancement of hyperenhancing masses. The use of biphasic enteric contrast agents at MR imaging may help overcome this limitation. 

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On T2-weighted images, small-bowel masses display signal intensity lower than that of intraluminal fluid, a characteristic that may help identify masses that don’t show substantial enhancement after intravenous contrast material is administered. A pitfall of T2-weighted imaging is the low-signal-intensity voids that can occur in the lumen because of peristalsis. HASTE sequences are more susceptible to this effect than balanced SSFP sequences are . Spasmolytics may help reduce the signal void artifact. There is a paucity of data regarding the sensitivity of MR imaging for the detection of small-bowel masses. However, in one study , no significant difference was found between MR imaging and wireless capsule endoscopy for the detection of large, clinically significant polyps in patients with polyposis syndromes, and there was improved localization with MR imaging