[Indication and Technical Tips for Flow Diveter Placement:Pipeline and FRED].

More than 2000 patients with large aneurysms have been treated with PipelineTM Flex since approval in 2015. The indication of PipelineTM Flex has expanded according to the PREMIER trial. Moreover, FREDTM has been approved in 2020 with a wider indication compared to that of PipelineTM. Aneurysms with 5 mm or larger of the maximum diameter in the internal carotid artery(ICA)and vertebral artery(VA)are currently indicated for PipelineTM. Moreover, the indications for FREDTM include the proximal anterior cerebral, proximal middle cerebral artery, and basilar artery in addition to the ICA and VA. The use in the acute stage of subarachnoid hemorrhage remains contraindicated for both. One should note several specific technical tips for these flow diverters. FREDTM can be deployed more easily compared to PipelineTM due to the large caliper filament and the flare ends. However, FREDTM is generally resistant to balloon angioplasty after it is fully deployed, most probably because the anchored flare ends disable foreshortening of FREDTM. Concomitant use of coiling may be recommended for intradural aneurysms to potentially minimize the risk of delayed rupture.