RT Journal Article SR Electronic T1 Republished: Pipeline embolization device induced collateral channels in elective flow diversion treatment JF Journal of NeuroInterventional Surgery JO J NeuroIntervent Surg FD BMJ Publishing Group Ltd. SP e1 OP e1 DO 10.1136/neurintsurg-2016-012297.rep VO 9 IS 1 A1 Yingming Amy Chen A1 Brian J Drake A1 Albert Ho Yuen Chiu A1 Thomas R Marotta YR 2017 UL http://jnis.bmj.com/content/9/1/e1.abstract AB The pipeline embolization device (PED) is a well recognized treatment for intracranial aneurysms. However, uncertainty remains regarding its effects on flow alteration, which is particularly highlighted by persistently perfused aneurysmal remnants and non-regressing, non-perfused aneurysmal masses. Here we present a 68-year-old woman with an incidental giant fusiform right paraophthalmic aneurysm electively treated with a PED. After lowering her antiplatelet therapy to promote aneurysm thrombosis, she was found to have a progressively enlarging perfused aneurysmal remnant. Angiography revealed PED occlusion, but curiously the development of a peri-construct collateral channel which feeds the aneurysmal remnant, and gives rise to distal branches and contributes to middle cerebral artery flow. The large ‘thrombosed’ aneurysmal mass showed tiny internal vessels on cone beam CT angiography as well as florid enhancement on MRI, further confirming that apparently thrombosed remnants are biologically active and may be remodeled depending on flow demand.