This can be solved by negative oral contrast
agents; some juices have also the effect to darken the stomach and bowel and can also be used as a contrast medium.
This prevents that liquid disturbs the image in the stomach and intestine field.
Pineapple and blueberry juices are useable as natural contrast media because of their content of manganese (a paramagnetic material). For more information see this database entry: Negative Oral Contrast Agents.