ABSTRACT. CT enterography is a new non-invasive imaging technique that offers superior small bowel visualisation compared with standard abdomino-pelvic CT, and provides complementary diagnostic information to capsule endoscopy and MRI enterography. CT enterography is well tolerated by patients and enables accurate, efficient assessment of pathology arising from the small bowel wall or surrounding organs. This article reviews the clinical role of CT enterography, and offers practical tips for optimising technique and accurate interpretation. Until recently, diagnosis of small bowel pathology had relied primarily on radiological techniques, in part due to the relative inaccessibility of the small bowel to conventional endoscopy. However, new endoscopic developments-notably the recent introduction of capsule endoscopy and double balloon enteroscopy-are challenging this position. Capsule endoscopy, for example, is now generally accepted as first-line investigation for occult gastrointestinal haemorrhage, and increasingly advocated for diagnosis of early Crohn's disease. However, the radiological community has not stood still. In parallel with the development of new endoscopic techniques, rapid progress has been made in crosssectional imaging technologies, harnessing the power of multidetector row CT (MDCT), MRI and ultrasound, facilitating rapid, accurate and minimally invasive investigation of the small bowel and adjacent tissues.CT enterography was first introduced by Raptopoulos et al [1] in 1997 as a modification to ''standard'' abdomino-pelvic CT examination to specifically examine the small bowel in detail, notably to assess the extent and severity of Crohn's disease [1,2]. They combined neutral (low-density) oral contrast with ''enteric phase'' CT to optimise contrast resolution between mucosa and lumen, thereby maximising conspicuity of abnormalities arising from the small bowel wall. Several authors have subsequently described similar techniques, which are broadly categorised into CT enterography (where patients drink oral contrast) and CT enteroclysis (luminal contrast is introduced via a nasojejunal tube placed fluoroscopically prior to CT examination). Although superior jejunal distension is attained using enteroclysis, the convenience, efficiency and superior patient experience achieved with CT enterography make it the preferred technique at the authors' institutions, and therefore the focus of this review. This paper will critically review the CT enterography technique and provide practical tips on interpretation to assist radiologists and help them avoid common interpretative pitfalls. We will also examine its role relative to other complementary non-ionising radiation radiological tests.
TechniqueThe technique of CT enterography combines small bowel distension with a neutral or low-density oral contrast mixture and abdomino-pelvic CT examination during the enteric phase following administration of intravenous contrast. Patients drink approximately 1.5-2 l of oral contrast over 45-60 min. Patient comp...