Flow diversion is a type of endovascular treatment for brain aneurysms. It is based on two concepts:
1) the placement of a high-mesh density stent (or flow diverter) in the parent 
vessel blocks blood flow into the aneurysm
2) the flow diverter stent also provides a scaffold for new blood vessel cells (called endothelium) to grow. This seals the aneurysm off from the main artery.
Flow diversion thus allows for progressive clot to form in the aneurysm over time with subsequent cure of the aneurysm. The advantage of flow diversion over coiling is the ability to treat the weakened abnormal artery wall by providing a scaffold for neo-endothelization to occur. This neo-endothelialization process results in a durable occlusion of the aneurysm that often provides a curative outcome as compared to the known recurrence associated with coiling.
Pipeline™ Embolization Device (PED) is the original flow diverter invented in 2007. It is also currently the only flow diverter that is approved for commercial use in the United States by the Food and Drug Administration (FDA).
This is an example of a giant brain aneurysm that was treated with the PED flow diverter. Follow-up angiogram done in 3 months show that the aneurysm is cured completely! This aneurysm will not recur (or come back)!
Dr. Li-Mei Lin 