Danielle .....
Looking back at your previous posts, it seems you were told you had an AN that was discovered on an MRI for another reason ..... and the purpose of this MRI was to determine the size of it now.
As with the others, I am not a doctor nor would I presume to be able to read your MRI. However, I do know the scanner takes many, many cuts (pictures) of the interior of your skull and the one you posted is only one of them. Each cut is slightly different and the radiologist looks at all of them to make the determination of the size of anything within the scanned views.
One thing I always do is pick up a copy of the MRI report as soon as it is ready (usually within 48 hours). The report should state the size and location of the AN, even if you cannot identify it from the images you pulled up on your computer from the CD ROM. The danger in reading the report yourself is to not panic if you read something you think might be serious, when it may be normal.
Like Jim said, I hope you can busy yourself with fun things to do right now ..... until you hear back from the doctor. ANs are typically very slow growing so you should have time to know all of your options before needing to choose a path of treatment.
Best thoughts.
Clarice