As described with CT enterography, this requires the patient to ingest a large volume of oral contrast in a set time period. Additionally, the use of glucagon or prone imaging may help to Crohn Disease decrease bowel peristalsis and thus artifact. MR enterography holds excellent test performance characteristics (see below) equivalent to other optimized modalities, such as CT enterography. The performance of MR enterography for CD is very good. Rates of sensitivity and specificity are 77% to 82% and 80% to 100%, respectively [24,66,67]; MR enterography can accurately display bowel-wall changes in CD [51-54]. Characteristic bowel-wall changes suggesting active inflammation include bowel-wall thickening, high T2 mural signal, mural hyper enhancement with mural stratification, and hyperemic vasa recta [55-64]. MR cine imaging is potentially useful, allowing for assessment of decreased bowel motility in the affected segments with CD [65]. Besides inflammation, MRI can detect complications for CD that include obstruction, abscess, or fistula. Test performance characteristics for complications are similar to CT enterography [27,28,35,40,68,69]. Overall, MRI is more prone to respiratory and bowel-motion artifact, despite the use of glucagon, which may lead to suboptimal examinations and more difficult interpretations. MRI Abdomen and Pelvis Standard MRI with a routine protocol (ie, MRI without and with IV contrast and without oral contrast enterography technique) can detect evidence of CD if the patient cannot tolerate large volumes of oral contrast. However, the lack of bowel optimization decreases evaluation of inflammation compared with MR enterography with optimized bowel technique. One study (n = 100) reported a sensitivity of 50% to 86% and specificity of 93% to 94% for wall thickening [73]. For CD complications, the diagnostic ability of MRI is similar to its CT counterpart with similar reported sensitivities and specificities in various series [27,40,58,72].
Crohn Disease. As described with CT enterography, this requires the patient to ingest a large volume of oral contrast in a set time period. Additionally, the use of glucagon or prone imaging may help to Crohn Disease decrease bowel peristalsis and thus artifact. MR enterography holds excellent test performance characteristics (see below) equivalent to other optimized modalities, such as CT enterography. The performance of MR enterography for CD is very good. Rates of sensitivity and specificity are 77% to 82% and 80% to 100%, respectively [24,66,67]; MR enterography can accurately display bowel-wall changes in CD [51-54]. Characteristic bowel-wall changes suggesting active inflammation include bowel-wall thickening, high T2 mural signal, mural hyper enhancement with mural stratification, and hyperemic vasa recta [55-64]. MR cine imaging is potentially useful, allowing for assessment of decreased bowel motility in the affected segments with CD [65]. Besides inflammation, MRI can detect complications for CD that include obstruction, abscess, or fistula. Test performance characteristics for complications are similar to CT enterography [27,28,35,40,68,69]. Overall, MRI is more prone to respiratory and bowel-motion artifact, despite the use of glucagon, which may lead to suboptimal examinations and more difficult interpretations. MRI Abdomen and Pelvis Standard MRI with a routine protocol (ie, MRI without and with IV contrast and without oral contrast enterography technique) can detect evidence of CD if the patient cannot tolerate large volumes of oral contrast. However, the lack of bowel optimization decreases evaluation of inflammation compared with MR enterography with optimized bowel technique. One study (n = 100) reported a sensitivity of 50% to 86% and specificity of 93% to 94% for wall thickening [73]. For CD complications, the diagnostic ability of MRI is similar to its CT counterpart with similar reported sensitivities and specificities in various series [27,40,58,72].