The role of MRE in this scenario includes diagnosis, delineation of disease extent including discrimination of Crohn disease from ulcerative colitis, depiction of extraintestinal manifestations of Crohn disease, and detection of penetrating disease complications that may influence treatment decisions. The latter may include fistulae that may be indicators for biologic therapy or abscess formation that may necessitate antibiotics and/or drainage. Evaluation of small bowel disease is an especially important role for MRE given the limitations of optical endoscopy in small bowel accessibility and visualization, particularly when Crohn disease terminal ileitis causes luminal narrowing [1]. Radiography Abdomen Visualization of bowel pathology is limited on abdominal radiographs, which often restricts utilization for initial diagnoses. US Abdomen Ultrasound (US) abdomen can be used for imaging Crohn disease during initial diagnosis. US may be a suitable alternative for evaluation of the terminal ileum in younger children who would otherwise require sedation for MRE Crohn Disease-Child or CTE examinations [21]. Sonographic technique requires a systematic assessment of the entire bowel including terminal ileum, colon, and more proximal small bowel. All four quadrants of the bowel should be evaluated in both the transverse and longitudinal planes [32]. Color Doppler US is also performed to facilitate hyperemia assessment. Sonographic features include abnormal bowel wall thickening (>3 mm in children), alteration of bowel wall signature, adjacent fatty proliferation, hyperemia, and engorgement of the vasa recta [32]. Patient features may adversely affect US including elevated body mass index as well as bowel gas resulting in shadowing. In the setting of pediatric Crohn disease though, obesity is less likely given that many patients have diminished nutrition [32]. The detection of alternative diagnoses is also decreased compared with CT or MRI.
Crohn Disease Child. The role of MRE in this scenario includes diagnosis, delineation of disease extent including discrimination of Crohn disease from ulcerative colitis, depiction of extraintestinal manifestations of Crohn disease, and detection of penetrating disease complications that may influence treatment decisions. The latter may include fistulae that may be indicators for biologic therapy or abscess formation that may necessitate antibiotics and/or drainage. Evaluation of small bowel disease is an especially important role for MRE given the limitations of optical endoscopy in small bowel accessibility and visualization, particularly when Crohn disease terminal ileitis causes luminal narrowing [1]. Radiography Abdomen Visualization of bowel pathology is limited on abdominal radiographs, which often restricts utilization for initial diagnoses. US Abdomen Ultrasound (US) abdomen can be used for imaging Crohn disease during initial diagnosis. US may be a suitable alternative for evaluation of the terminal ileum in younger children who would otherwise require sedation for MRE Crohn Disease-Child or CTE examinations [21]. Sonographic technique requires a systematic assessment of the entire bowel including terminal ileum, colon, and more proximal small bowel. All four quadrants of the bowel should be evaluated in both the transverse and longitudinal planes [32]. Color Doppler US is also performed to facilitate hyperemia assessment. Sonographic features include abnormal bowel wall thickening (>3 mm in children), alteration of bowel wall signature, adjacent fatty proliferation, hyperemia, and engorgement of the vasa recta [32]. Patient features may adversely affect US including elevated body mass index as well as bowel gas resulting in shadowing. In the setting of pediatric Crohn disease though, obesity is less likely given that many patients have diminished nutrition [32]. The detection of alternative diagnoses is also decreased compared with CT or MRI.