There are several types. However, you may need more than one type – for a CT scan, it is common to require IV and oral contrast. IV contrast is used to enhance the vascular system and the organs that have a good blood supply. The contrast you drink is for the bowel, which doesn’t enhance with IV contrast. Contrast can also be injected directly into the spinal canal or brain ventricles for certain procedures.
I work in a radiology in a paediatric hospital, and deal with this issue every day. There are a few options, in order of priority:
1. Gently try to convince the child, depending on his/her age, of the importance of drinking it.
2. Dilute the contrast with juice, lemonade, or another soft drink (NOT milk) rather than water. The sugar can mask the taste of the contrast.
3. Oral contrast is usually either Barium or Iodine based. If one isn’t working, try the other. Neither taste good though.
4. If the scan absolutely requires contrast, and point 2 doesn’t work, a nasogastric (NG) tube can be inserted, and the contrast injected directly into the stomach. If the child has reflux, a transpyloric tube (TPT) may be preferable, but these can be difficult to insert.