finding this during my MRI research doesn't make me feel better

Normally, for a hip MRI the contrast is NOT injected into the bloodstream. It sounds like they are going to be doing an arthrogram. It's pretty common. The Radiologist will inject some contrast directly into your hip joint. They numb it as best they can but I am sure it will be uncomfortable. Once the contrast is in your hip joint, you then go over to the MRI machine and they will scan your hip. Having the contrast in the hip joint helps the doctors diagnose tears within the joint. Your hip will be pretty stiff the rest of the day until your body absorbs the contrast. The worst part will be the injection of the contrast, after that it will be all downhill.