Coil thickness and packing of cerebral aneurysms: a comparative study of two types of coils.

BACKGROUND AND PURPOSE In coiling cerebral aneurysms, high packing prevents reopening over time. The purpose of this study was to compare packing of cerebral aneurysms treated with two types of coils with different wire thickness and different shapes. METHODS Packing, defined as the ratio between the volume of inserted coils and the volume of an aneurysm, was calculated for 144 cerebral aneurysms treated in 130 patients. Seventy-two aneurysms were treated with predominantly helical-shaped coils of 0.010-inch-diameter wire, and 72 aneurysms were treated with predominantly complex-shaped coils of 0.012-inch-diameter wire. Aneurysm volume was assessed from three-dimensional angiography. Aneurysm packing, inserted coil lengths, and numbers of coils were compared for both types of coils. RESULTS Mean packing was significantly higher (absolute value, 6.4%; relative value, 26.6%; P < .0001) in aneurysms coiled with 0.012-inch-diameter coils than aneurysms coiled with 0.010-inch-diameter coils. Inserted coil length per cubic millimeter of aneurysmal volume was equal for both types of coils. CONCLUSION Use of complex-shaped coils with a wire diameter of 0.012 inch to coil cerebral aneurysms results in significantly better packing than is achieved with helical coils of 0.010-inch-diameter wire.