Low-attenuation oral GI contrast agents in abdominal-pelvic computed tomography

Background: We designed and evaluated a low-attenuation oral contrast agent for abdominal-pelvic computed tomography (CT). Methods: In vitro studies, were performed initially to evaluate the imaging characteristics of multiple solutions. These studies resulted in two solutions being compared with the presently accepted oral CT agents of dilute iodinated contrast and water. Ninety-eight consecutive subjects already scheduled for routine outpatient abdominal-pelvic CT were enrolled. Subjects were randomized to water (n = 30), fiber solution (n = 32), polyethylene glycol (PEG; n = 11), or dilute iodinated solution (DI; n = 25). Examinations were then evaluated for gastric distention, small bowel distention, small bowel wall visualization, and colonic transit. A questionnaire was given to the study subjects for feedback concerning taste and potential side effects from these agents. Results: PEG tended to provide better bowel distention, wall visualization, and colonic transit compared with water, fiber solution, and DI. Areas of statistical significance included: (1) average bowel diameter in the left upper quadrant for water was 17.50 mm, whereas that for PEG was 21.88 mm (p < 0.05); (2) average bowel diameter in the pelvis for water was 14.79 mm, that for fiber was 15.67 mm, and that for PEG was 18.48 mm (p < 0.05); (3) wall visualization was better with PEG than with fiber (p < 0.05); (4) successful transit of contrast to the colon occurred in every subject who received PEG compared with only 20% of those received water and 39% of those who received fiber (p < 0.05). Similar trends for the superiority of PEG over DI were noted, although many of these did not reach statistical significance. Conclusion: PEG solution has imaging characteristics related to bowel wall visualization, luminal distention, and colonic transit that make it an effective oral agent for abdominal pelvic CT examination.