Hi vap119,
If the doctors you've seen can't determine whether they're seeing residual tumor or scar tissue on the MRI, then perhaps the "wait 3 months and redo the MRI" strategy would be good. It would let you know if any residual tumor is growing or not. If it isn't, perhaps you could re-evaulate again in 6 months or a year with another MRI. Your neurosurgeon has an advantage in that he (or she) has seen the actual tumor, and has already said that they left some tumor in place, and that can help them interpret the MRI images. It's not unusual for the surgical team to leave some residual tumor if attempting to remove the last of it would endanger cranial nerves (normally the facial nerve), and the remainder can be treated with radiation if needed.
Another option would be to send the MRI to a couple of other AN treatment centers for evaluation. There are several that will review an AN MRI for free.
Regards,
Rob