Doctor suspects avm or narrowing of vessels in brain from mri. have upcoming angiogram. can they be wrong. im told this is strictly for exploration. ?

Probably correct: Probably correct to do further studies for brain MRI findings. It is for evaluation (not "exploration"), and if there is a problem it may be addressed pro-actively if you agree with their recommendations.

Possibly: Mris are good screening tests for the avm. The final test is the angiogram. That is because this is a dynamic test, meaning that one can see the flow of the blood in the vessels. This will help with defining the anatomy of the vessels in the abnormality. As to whether an MRI may be wrong in diagnosing an avm, that is possible if the findings on the MRI are not clear.