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

Rationale and Objectives. The authors evaluated the use of MRX-320, a low-a ttenuation, expansile oral contrast agent, for the demonstration of intesti nal ischemia in an animal model. Materials and Methods. Nine dogs were given either MRX-320, water, or diatr izoate as an oral contrast agent through a jejunostomy tube. Two dogs recei ved 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 t he arterial phase, and during the portal venous phase. Mesenteric ischemia was surgically induced, and the imaging protocol was repeated. Three reader s rated the randomly assigned images for quality and demonstration of ische mia. Attenuation values for the intestinal lumen and wall were recorded. Results. Examinations performed with MRX-320 provided the best discriminati on between ischemic and nonischemic conditions (P < .05), followed by exami nations with no oral contrast medium, examinations with water. and examinat ions with diatrizoate. Images obtained with MRX-320 also scored significant ly 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 pr ovided the least uniformity of distention, and diatrizoate provided the lea st mucosal detail. Conclusion. The use of MRX-320 as an oral contrast agent with an intravenou s bolus of iohexol at CT increased reader confidence for the diagnosis of i ntestinal ischemia and improved subjective measures of image quality.