This looks like a small bubble forming on the wall of the artery.
Cerebral aneurysms can be present in the brain for years without causing symptoms.
However, over time. Previously, the only treatment was an operation on the brain by a neurosurgeon in which a metal clip is placed at the neck of the aneurysm. Detachable Coil Treatment performed by the neurointerventional radiologist can be done to prevent rupture and bleeding from the cerebral aneurysm. This is done with a small catheter which is advanced from the femoral artery in the groin all the way up into the artery in the brain into the aneurysm cavity. Small detachable coils are then advanced into the aneurysm sac, The coils fills the sac and causes the aneurysm sac to undergo thrombosis.