How long to get MRI results?

Having a brain MRI tomorrow that I had to beg my doctor for since he didn't think it was necessary. I've had dizziness over a few days and got an exertion headache last week and I am anxious about a brain tumor. Will they tell me over the phone or quickly if something is wrong? I don't want to have to make an appointment weeks from now to find out I have a brain tumor that's gonna kill me! I have been going mental since my ER visit. I had a clear CT but still, I know I've posted questions like this but I've never done this kind of stuff and I'm terrified to be honest.