Focal increased cortical density in immediate postembolization CT scans of patients with intracranial aneurysms.

BACKGROUND AND PURPOSE Cortical hyperdensity was observed in the immediate postembolization CT scans of some patients with intracranial aneurysms following uneventful endovascular treatments. The clinical significance and possible underlying mechanism were evaluated. MATERIAL AND METHODS Ninety-three consecutive patients with a total of 100 intracranial aneurysms, treated by endosaccular packing, were studied. Seventy-four aneurysms were treated with balloon assistance, and the remaining aneurysms were treated without balloon assistance. All patients underwent cranial CT just before and immediately after the endovascular treatment. If the post-treatment CT showed any new finding, an immediate MR imaging and a repeat CT 4-6 hours after the initial posttreatment CT were performed. Several parameters were investigated related to the presence of cortical hyperdensity. RESULTS Cranial CT showed focal cortical hyperdensity following the treatment of 40/74 aneurysms (54%) with balloon remodeling and 9/26 aneurysms (34.6%) without balloon assistance. None of these patients were symptomatic, and cortical hyperdensity resolved in the repeat CT scans. A statistically significant relationship was observed between the presence of this finding and the total amount of contrast material, microcatheter time, number of balloon inflations, and total balloon inflation time. CONCLUSION Immediate postembolization CT may show focal cortical hyperdensity following uneventful endovascular aneurysm treatment, most likely caused by blood-brain barrier disruption resulting in accumulation of contrast medium. The hyperdensity was more frequent when balloon assistance was used but was also seen in the patients with no balloon use. It is important to differentiate this clinically insignificant finding from possible hemorrhage, which would affect patients' immediate postprocedural medical management.