Fenestrated ACA

Non contrast 3 D TOF MR Angiogram of Brain

Fenestration is a window or a ring produced by a segment of an artery.

Duplication and fenestration of artery both are considered as rare developmental anomalies but are used incorrectly and interchangeably. 

Duplication should be strictly applied to the artery that has 2 origins and a variable course with or without reunion in the same anatomical area.

In contrast, fenestration represents a vessel with a single origin, anywhere along its course the main trunk divides and reunites again forming a window or a ring.