Trial Information

Oral Iohexol for Fecal/Fluid Tagging for CT Colonography: A Study to Improve Image Quality by Preventing Colonic Bubbles

CT colonography (CTC) is a recently developed radiological examination to find colorectal
neoplasia. Fecal/fluid tagging using oral administration of contrast is an essential
procedure for CTC. Iohexol, which has recently started being used as an agent for
fecal/fluid tagging, has great advantages as it has much more tolerable taste and much lower
rates of adverse effects such as clamping or diarrhea compared with traditionally used
Gastrografin/Gastroview. However, iohexol is frequently associated with an occurrence of a
lot of bubbles in the colon, which makes CTC interpretation more time-consuming and
laborious.

Past experience in colonoscopy field suggests that simethicone, a safety-proven highly
inexpensive over-the-counter medicine, might resolve this issue. Given the fact that patient
convenience is an important factor for a successful CTC and the fact that time-intensive
nature of CTC interpretation is one of the major deterrents to wide spread adoption of CTC
while CTC also needs to be as time efficient as possible in order to effectively serve the
role of population screening for colorectal cancer, investigating the effect of simethicone
to prevent the colonic bubbles on the time efficiency of CTC interpretation would be
important. If simethicone can resolve the colonic bubble problem, CTC can be performed more
conveniently for the patients as well as for the interpreting radiologists.

This study is to determine whether colonic bubbles associated with CT colonography performed
with iohexol for fecal/fluid tagging could be reduced and the interpretation time of the CT
colonography could be shortened by adding simethicone to the standard cathartic preparation.