Eosinophilic esophagitis is an immune-mediated hypersensitivity reaction to inhaled or ingested allergens which affects genetically susceptible individuals. The condition more commonly occurs in the third or fourth decade of life, with a male predominance (male to female ratio 3:1). The incidence is approximately 6 in 10,000 population. Patients usually present with difficulty in swallowing solids and with food impaction. Management options include dietary modification, medical therapy, or surgical dilatation for symptomatic strictures. Typical appearances on barium swallow which are highly specific for eosinophilic esophagitis consist of multiple persistent rings in the mid- and/or distal esophagus (Shanbhogue et al. 2010) (Fig. 16.3a). Compare this with tertiary contractions, which are temporary and a more common finding (Fig. 16.3b).

Gastric cancer is the fifth most common cause of cancer-related death worldwide. It is often diagnosed late and has a poor prognosis, with an overall 5-year survival rate of less than 20 % in the UK. Multi-detector CT (MDCT) is used to stage gastric carcinoma preoperatively. Imaging features of the stomach on MDCT can be misleading, especially if not protocolled specifically to assess for gastric carcinoma. Prone imaging and gas-forming granules to distend the stomach, as well as intravenous contrast administration, can increase the sensitivity and specificity of detecting pathological gastric wall thickening (Fig. 16.4a, b). The use of negative oral contrast may also be useful in increasing the conspicuity of subtle pathological gastric wall enhancement (Hargunania et al. 2009). Following esophageal surgery for esophageal carcinoma, imaging for recurrence can be particularly challenging, especially with abnormal anatomy (gastric pull-through). Patients often present with vague chest or upper abdominal symptoms. The search for ancillary signs, such as nodal enlargement and pathological soft-tissue enhancement, is often useful in diagnosing disease recurrence (Upponi et al. 2007) (Fig. 16.5).

Intestinal malrotation is a congenital abnormality, which can result in midgut volvulus. Neonates usually present in the first week of life with proximal small bowel obstruction and bilious vomiting. Approximately 25 % of cases are asymptomatic and are found incidentally in adult life. Malrotation has been associated with variations in pancreatic head contour. A bulky pancreatic head can be mistaken for pancreatic tumor, but in malrotation, the bulky pancreatic tissue is of the same attenuation and of the same enhancement pattern as normal pancreas (Chandra et al. 2012) (Fig. 16.8).

The small bowel enema requires insertion of a nasojejunal (NJ) tube before controlled administration of contrast agent via the NJ tube to delineate the small bowel. It is important to note that the duodenum is not usually opacified and pathology can be missed within this region. In the illustrated case, a small bowel enema study was performed where there was difficulty in NJ tube insertion. Following some contrast administration, there was an evident stricture at the junction of the second and third parts of the duodenum, obstructing the passage of the NJ tube (Fig. 16.9a, b). In this case, the pathology was demonstrated. However, if the stricture was less narrow, the tube may have passed and the contrast material may not have refluxed back far enough to delineate the duodenal tumor. The extent of visualization of the duodenum at gastroscopy is variable, so that the duodenum can be a “blind” area for both the endoscopist and the radiologist. This limitation may still apply with cross-sectional enteroclysis techniques (CT or MR enteroclysis).

Lymphoma of the small bowel can present in many morphological forms. Aneurysmal dilatation is quite specific but occurs in a minority of cases. There can be marked thickening of areas of involved bowel wall, with no ulceration and only minor change in caliber of the lumen or distortion of the valvulae conniventes. At barium examinations, therefore, the abnormalities can be very subtle (Fig. 16.10a). On CT, the abnormality is much more conspicuous with gross focal bowel wall thickening (Ghai et al. 2007) (Fig. 16.10b).