Value of brominated fluorocarbons for the radiographic diagnosis of small- bowel obstruction: Comparison with other contrast agents in rats

OBJECTIVE. The disadvantages of water-soluble gastrointestinal contrast agents include high osmolality, contrast dilution, and severe toxicity if aspirated. Perfluorocarbons are nontoxic in the lung and peritoneal cavity. Because perfluorocarbons are immiscible with water, they have no osmotic effect and cannot be diluted. Because these properties offer theoretical advantages over traditional gastrointestinal contrast agents, we compared two perfluorocarbons with barium and ionic and nonionic iodinated contrast material in a rat model of small-bowel obstruction. MATERIALS AND METHODS. Twelve groups of six rats each had ligation of the terminal ileum (obstruction model) or of the terminal ileum and mesenteric artery (obstruction with ischemia model). Each rat received 3 ml of barium, meglumine sodium diatrizoate, iohexol, neat perfluorooctyl bromide, neat perfluorohexyl bromide, or saline (control animals). Contrast media were given at the recommended concentrations, and their progression was evaluated on serial radiographs by an observer who was not aware of the model or the contrast medium given. When one contrast material reached the point of obstruction, all rats in the group were sacrificed and a final radiograph was obtained. Three radiologists, who were not aware of the contrast medium given, on two separate occasions independently reviewed the radiographs and ranked the contrast agents for their relative radiopacity, mucosal definition, speed of transit, gastric retention, and bowel distension. RESULTS. When data from both models were combined, perfluorocarbons were judged on the final image to be the most radiodense, to provide the sharpest mucosal detail, to have the least gastric retention, and to have faster progression than barium. Whereas meglumine sodium diatrizoate and iohexol reached the point of obstruction more rapidly than the perfluorocarbons and barium, they had the greatest gastric retention, caused the most bowel distension, and were the least radiopaque. CONCLUSION. Our results show that the radiopaque perfluorocarbons are suitable as gastrointestinal contrast agents and have favorable radiographic characteristics in this animal model. When these results are combined with the low-toxicity profile of perflubron, clinical evaluation of this agent for the radiographic assessment of bowel obstruction is warranted.