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 followup after treatmen t 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 b all could accurately predict the presence of unstable angiographic occlusio n. Paired GDC radiographs (in two planes) and cerebral angiograms, performe d 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 in terval between followup angiographic examinations after GDC treatment safel y if there is no change in the radiographic appearances in two planes.