Oral contrast agents for small bowel distension in MRI: influence of the osmolarity for small bowel distention

To assess the effect of the osmolarity for small bowel distension in MRI, ten volunteers ingested at two separate occasions negative oral contrast agents with different quantity and osmolarity: (1) a water solution combined with 2.0% sorbitol and 0.2% locus bean gum (LBG) with a quantity of 1500 ml and an osmolarity of 148 mOsmol/l, (2) a water solution combined with 2.0% sorbitol and 2.0% barium sulphate with a quantity of 1000 ml and an osmolarity of 194 mOsmol/l. Small bowel distension was quantified on coronal 2D-TrueFISP images by measuring the small bowel diameters. There were no statistically significant differences in mean small bowel diameter between both contrast agents. The mean small bowel distension was 19.2 mm after ingestion of 1500 ml of sorbitol-LBG solution and 19.0 mm after ingestion of 1000-ml sorbitol–barium sulphate solution. Furthermore, all volunteers found the ingestion of 1000-ml solution more pleasant than the 1500-ml solution. The ingestion of 1000 ml of sorbitol–barium sulphate solution led to a sufficient small bowel distension compared to 1500 ml of sorbitol–LBG solution. The side effect rate of both solutions was low. Based on these data, we recommend a quantity of 1000 ml of sorbitol–barium sulphate solution as an alternative for 1500-ml sorbitol–LBG solution for optimal bowel distension.