The use of dilute Calogen as a fat density oral contrast medium in upper abdominal computed tomography, compared with the use of water and positive oral contrast media.

Objective: Oral contrast media are commonly given prior to computed tomography (CT) examination of the upper abdomen. Although positive oral contrast media are normally used, there is increasing interest in using negative agents such as water and less commonly fat density products. The aim of this study was to compare a positive oral contrast medium, water, and a diluted emulsion of arachis oil Calogen, a fat density food supplement) for assessment of the upper abdomen.

Methods: Seventy-one patients referred for upper abdominal CT were randomized to receive either 500 ml water, 2% sodium diatrizoate or a dilute suspension of Calogen. The CT images were scored independently by three radiologists. Distension and anatomical identification was assessed for the stomach, duodenum and jejunum; with anatomical identification recorded for the pancreas, retroperitoneum, liver, gallbladder and spleen.

Results: Dilute Calogen produced a significant improvement (P < 0.01) in distension and anatomical visualization of the stomach and proximal duodenum. Only minimal differences were demonstrated between the three contrast media for visualization of more distal small bowel or identification of the other upper abdominal viscera. Significantly more artifacts were caused by positive contrast media than with the Calogen mixture.

Conclusions: A dilute suspension of Calogen as an oral contrast medium is recommended when disease is suspected within the stomach or proximal duodenum.