Evaluation of an experimental low-attenuation gastrointestinal contrast agent for CT imaging of intestinal ischemia in an animal model.

ABSTRACT

RATIONALE AND OBJECTIVES: The authors evaluated the use of MRX-320, a low-attenuation, expansile oral contrast agent, for the demonstration of intestinal ischemia in an animal model. MATERIALS AND METHODS: Nine dogs were given either MRX-320, water, or diatrizoate as an oral contrast agent through a jejunostomy tube. Two dogs received no oral contrast agent. Helical computed tomography (CT) was performed before the intravenous injection of 2.5 mL/kg iohexol at 4 mL/sec, during the arterial phase, and during the portal venous phase. Mesenteric ischemia was surgically induced, and the imaging protocol was repeated. Three readers rated the randomly assigned images for quality and demonstration of ischemia. Attenuation values for the intestinal lumen and wall were recorded. RESULTS: Examinations performed with MRX-320 provided the best discrimination between ischemic and nonischemic conditions (P < .05), followed by examinations with no oral contrast medium, examinations with water, and examinations with diatrizoate. Images obtained with MRX-320 also scored significantly higher on measures of image quality than those obtained with water or no oral contrast medium (P < .05). On images obtained with MRX-320, the bowel lumen measured -836.5 HU (P < .05 compared with other techniques). Water provided the least uniformity of distention, and diatrizoate provided the least mucosal detail. CONCLUSION: The use of MRX-320 as an oral contrast agent with an intravenous bolus of iohexol at CT increased reader confidence for the diagnosis of intestinal ischemia and improved subjective measures of image quality.