Alright, folks, it's time for another installment of name that lesion. (Ok, so maybe it's the first, can't remember.)

Today in Neuroscience we had two hours of lecture on various neuroimaging techniques. One of the techniques described was digital subtraction angiography. Basically you take a regular x-ray, inject contrast media, and then take another x-ray. A computer digitally subtracts everything that is not filled with contrast, so you end up with a picture of only the cerebral arteries. The following example was shown in class:

[1]
Click for larger image

Can you name that lesion? Be specific! (Vessel, suspected patient signs/symptoms)

Answers will be announced in a couple of days, as well as after-intervention pictures. No prizes other than self-satisfaction.

Update: This entry has been promoted to a "sticky" post until I get some more entries. Answer will be revealed on Monday.