The accuracy of plain skull x-ray examination as a predictor of recanalization following Guglielmi Detachable Coil embolisation in the treatment of cerebral aneurysms

We evaluated the accuracy of plain skull x-ray series as an imaging modality for the follow-up of cerebral aneurysm recanalization after Guglielmi Detachable Coil (GDC) embolisation. We retrospectively reviewed of 100 consecutive follow-up angiograms and skull x-ray examinations in 78 patients harboring 82 aneurysms and in whom 85 procedures were performed. Angiography was performed between 1 and 54 months (mean: 10.8 months) after embolisation. The skull series (AP, lateral and Towne's projections) were taken at the time of follow-up angiography. Each follow-up angiogram and skull series were compared to the immediate post-coiling, correlating presence or absence of coil compaction on the skull series and recanalization of the aneurysm at angiography. In 97 (97%) examinations skull x-ray findings correlated with the angiographic findings. In three cases skull x-ray examination suggested compaction when no recanalization was seen angiographically; in these three cases, the aneurysms were small and found to be more thrombosed than baseline. In no case did angiographic recanalization occur in the absence of compaction on skull series. These findings yield 100% sensitivity, 95% specificity, 93% positive predictive value, 100% negative predictive value and 97% accuracy. The location size, configuration and neck/dome ratio of the aneurysm were not related to the correlation between angiography and skull x-ray exam. Skull x-ray series is a safe, accurate, and cost-effective mode of follow-up for patients with GDC-treated aneurysms. The possibility of it replacing angiography still requires a more comparative skull x-ray modality in follow-up studies.