Welcome to this forum, Sue!
Tell us a little bit more about what symptoms prompted the order for an MRI.
An MRI with contrast is the definitive way to diagnose an AN ...... note the stress that it must be with contrast. As to how long to wait for MRI results, this depends so much on the facility doing the MRI and how/when they communicate results to the ordering physician. I learned the hard way to wait following the actual MRI for my own copy of the CD/ROM and to go back and pick up a copy of the radiologist's report as soon as it is available (in my situation usually 48 hours). It is your body and they have to give you these things. The downside to that is knowing how to interpret what you see or read. In most cases it is better to wait for the ordering physician to go over the results with you. The reason I do not wait for the doctor now is because there was some kind of a communication mix-up at the time of my diagnosing MRI and I falsely thought I was in the clear when I did not hear anything. Ten days later I went to my follow-up visit with the ENT alone and was told I had a 2+cm AN that needed to be dealt with rather immediately. I was in such a state of shock I did not know what to ask ..... not a good feeling.
As to the pressure feeling in the head, depending upon where an AN is actually located, presenting symptoms can be quite different. I never had the pressure feeling until during post surgery recovery. I also did not have tinnitus (roaring sound) until post-treatment. I did have the dizziness/balance issues, full ear, and hearing loss.
Let us know what you find out. I pray it is not an AN but whatever it is, we are here to support you in any way we can.
Clarice