Can a basilar artery fenestration be confused with an acquired focal arterial dissection by a radiologist? i had an mri/mra and am afraid that its really not basilar artery fenestration that i was born with but arterial dissection (which is worse)?

The images are so different so I doubt if the radiologist would make an error in the reading. Furthermore, basilar artery dissection is a rare but life threatening condition. I wonder what your symptoms were for prompting a brain MRA.

Yes. They can be confused! A fenestration, rare, is something you may be born with. It may have no symptoms, or sometimes an aneurysm can form in the vicinity. A dissection and/or thrombus, which could lead to stroke can occur as well. I don't know why you had the MRI/MRA, but I would "definitely" let the Radiologist, and any doc treating you know that you have this anomaly.

Don’t just worry but indeed get proactive. Have your doctors directly review images and demonstrate why the conclusions were reached. If dissatisfied, have second radiologist do an over-read