Contrast causes ACTIVE lesions to light up. This tells them if you are in an active phase of the disease or if your symptoms and stuff are flare related and from other sources.

Drink drink drink after the test. Its flushed thru the kidneys and has been known in rare cases to cause kidney damage. Help yourself by flushing it on out. It can give folks a headache and or make them a bit more than nauseous whend first given. It generally passes quickly and before the test is done most report feeling much better.

Ask them to PUSH SLOW. I have had more than one case of swollen veins after because they are so aggressive to push the stuff in there. I ask them to hand push the stuff and go slow.