Medical Imaging in Small Bowel Crohn's Disease-Computer Tomography Enterography, Magnetic Resonance Enterography, and Ultrasound: "Which One Is the Best for What?"

Background: Small bowel imaging in Crohn's disease (CD) is an important adjunct to endoscopy for the diagnosis, assessment of postoperative recurrence, and detection of complications. The best imaging modality for such indications though remains unclear. This systematic review aims to identify the imaging modality of choice considering the use of ultrasound (US), computed tomography enterography (CTE), and magnetic resonance enterography (MRE). Methods: Databases were systematically searched for studies pertaining to the performance of US, CTE, and MRE, as compared with a predefined reference standard in the assessment of small bowel CD. Results: Thirty-three studies, from a total of 1427 studies, were included in the final analysis. A comparable performance was demonstrated for MRE, CTE, and US for the diagnosis of small CD. Ultrasound was found to have the highest accuracy in the differentiation of inflammation and fibrosis. Postoperative recurrence detection was feasible with the use of MRE and US. All 3 modalities were shown to have a role in the detection of small bowel CD complications. The radiation exposure associated with CTE can be minimized by using lower radiation protocols. Conclusions: Ultrasound, CTE, and MRE all play an important role in the diagnosis and management of small bowel CD, with preference for a particular modality being influenced by specific indication, institution resources, and patient preference.