The ability of plain radiography to predict intracranial aneurysm occlusion instability during follow-up of endosaccular treatment with Gugliemi detachable coils

Incomplete occlusion of an intracranial aneurysm at follow-up after treatment with Gugliemi detachable coils (GDC) increases the risk of rebleeding and serial angiographic monitoring is therefore currently indicated. We aimed to determine if a change in the plain radiographic appearances of the GDC ball could accurately predict the presence of unstable angiographic occlusion. Paired GDC radiographs (in two planes) and cerebral angiograms, performed immediately after treatment and at follow-up or at two consecutive follow-up examinations, were retrospectively compared. Radiographs were assessed for the radiographic change (loosening, compaction or reorientation) in the coil-ball and angiograms for unstable aneurysm occlusion (neck recurrence or deteriorating occlusion). We compared 49 paired films from 38 patients. Radiographic change in the coil ball had a negative predictive value of 96 %, positive predictive value of 57 % and accuracy of 76 % for the presence of angiographic aneurysm instability. It may be possible to increase the interval between follow-up angiographic examinations after GDC treatment safely if there is no change in the radiographic appearances in two planes.