Imaging Follow-Up of Intracranial Aneurysms Treated by Endovascular Means

Aneurysm treatment is dedicated to prevention of rupture (for unruptured aneurysms) or rebleeding (for ruptured aneurysms). Endovascular embolization has become the first-line treatment for intracranial aneurysms in the majority of cases in many institutions. This minimally invasive approach achieved lower morbidity and mortality rates when compared with surgical management.1–4 However, although successful in improving patient care, its durability has been noted to be its Achilles’ heel since the earliest application of this technology. Indeed, after endovascular treatment (EVT) ≈20% of patients will experience aneurysm or neck reopening after traditional endovascular coiling, necessitating retreatment in about half of them to maintain long-term protection over bleeding.5 Despite this issue, low rates of bleeding have been reported after EVT of ruptured aneurysms, and its clinical superiority over surgery seems to be maintained over time according to the long-term clinical follow-up of the International Subarachnoid Aneurysm Trial (ISAT) cohort.6,7 In the Cerebral Aneurysm Rerupture after Treatment (CARAT) study, the bleeding rate after coil embolization was 0.11% (mean follow-up time, 4.4 years), whereas in the International Subarachnoid Aneurysm Trial, the annual risk of bleeding after coil-treated aneurysms was 0.08%.8 In a large single-center study, the Barrow Ruptured Aneurysm Trial (BRAT), no bleeding was observed after 6 years in the coiling arm, but 4.6% of these patients were retreated.9Thus, one may question the clinical usefulness of performing imaging follow-up, balancing the small risk of bleeding after EVT with the cost-effectiveness of follow-up.Although the primary end points of these studies were clinical, it is important to note that the majority of EVT patients had imaging follow-up performed at the discretion of the treating physician. For example, in the ISAT trial, 88.2% of the patients in the EVT arm (881 patients) had follow-up angiograms, generally performed 6 …