Hi there,
I only had a brain one done. Are you getting them done on different days? Could be the type of scanner.
Yes, hospital gown, but not as bad as it sounds. Basically, you wait (ages), then they bring you into a room to get changed into a gown, then you get the scan done, change again and go home.
The MRI itself was ok - I found the physical restraint more unsettling than anything, but the noise was something else. Brain one took about 10 minutes - I could hear the scanner moving slowly around each area of my head.