Before going for the MRI her doctor discharged her, meaning we could return home immediately following the procedure.
The MRI was difficult - those who've had it before (or like me have read about it on wikipedia) will know it's incredibly noisy, which is rather unfortunate for those with head injuries. But for the 20 minutes of lying down that it took she managed to hold onto the contents of her stomach.
She's home now, and glad to be in her own bed, and has managed to keep her lunch and dinner down so far. She's glad to have my cooking (albeit just clear soup - I'm taking no risks) rather than the bleh they serve at the hospital.
We haven't heard from the doctor, so I can only presume the MRI came back OK, or he didn't hear. Either way I'm pleased with today's progress, and despite my apprehensions I am pleased she's home.