How are computed tomographic enterography (CTE) and magnetic resonance enterography (MRE) different from routine CT or MRI scans of the abdomen and pelvis?
CTE and MRE are tailored specifically for detailed evaluation of the small bowel. They are both obtained through the abdomen and pelvis after the administration of large volumes (>1 L) of neutral oral contrast material. Neutral oral contrast material has fluid attenuation on CT and fluid signal intensity on MRI (i.e., low T1-weighted and high T2-weighted signal intensity). This improves the distinction between the bowel wall and the bowel lumen while simultaneously distending the bowel lumen, allowing for improved detection of abnormal bowel wall pathology. Multiplanar thin section images are then typically obtained during one or more phases of intravenous contrast enhancement. MRE has superior soft tissue contrast compared to CTE, improving the detection of mural edema and mural hyperenhancement, and involves no radiation exposure but is more expensive and takes longer to perform than CTE.