Christine M. Peterson

To compare the efficacy and patient tolerance of iohexol and meglumine sodium diatrizoate as oral contrast agents for computed tomography (CT). One hundred patients were randomly assigned to drink 1000 mL of either meglumine sodium diatrizoate or iohexol 350 before their abdominopelvic CT examination. The images were evaluated independently and in a blinded fashion by 2 radiologists who scored the extent and density of bowel opacification. Attenuation value measurements were obtained in representative areas of each gastrointestinal tract segment (stomach, duodenum, jejunum, ileum, and colon) by a research technologist. Patients' tolerance of the oral contrast agent was assessed through a questionnaire administered immediately after the CT and with a follow-up phone call 2 to 3 days later. For most of the bowel, there was no statistically significant difference in the extent or degree of opacification between the 2 contrast agents. Opacification of the ileum was better with iohexol. There was no statistically significant difference between the 2 agents in adverse effects. Patients had a small but statistically significant preference for the taste of iohexol. Iohexol 350 is a satisfactory oral contrast agent for abdominopelvic CT. It opacifies the gastrointestinal tract as well as meglumine sodium diatrizoate does, and patients prefer the taste of iohexol to that of diatrizoate.

Volvulus of the gastrointestinal tract, a clinically relevant cause of acute or recurring abdominal pain in adults, remains a diagnostic dilemma for radiologists in a large number of cases. The clinical symptoms associated with volvulus are often nonspecific and include pain and nausea with vomiting. Yet referring clinicians often rely on radiologists to make the diagnosis; volvulus is rarely diagnosed clinically. Radiography, fluoroscopy, and computed tomography are the imaging methods most often used for this purpose. Prompt diagnosis is critical to avoid life-threatening complications such as bowel ischemia and infarction. Thus, it is useful for radiologists to be familiar with the various appearances of volvulus throughout the gastrointestinal tract.