Introduction The appearance of eclipse sign in large and giant aneurysm is a characteristic angiographic finding after flow  diversion. However, its clinical implication for prediction of successful embolization has not been fully investigated. We evaluated the angiographic appearance of eclipse sign in different phases of cerebral angiography pre and post PED placement in correlation with aneurysm thrombosis at 6 months.

Methods Angiographic and clinical data of 48 consecutive procedures was analyzed retrospectively. Patients who had: 1) successful PED placement without adjunctive coiling, 2) visible eclipse sign on post embolization angiography, 3) and reliable follow up angiographic data were included. Fisher’s exact test was used for statistical analysis.

Results Among all included patients, the median aneurysm size was 23mm (10–38), the median age was 53 (19–88), and 10% (2/19) were male. Thrombosis rate at 6 months was 84% (16/19). Pre-intervention eclipse sign was present in 63% of (12/19) analyzed patients. The baseline angiographic appearance of eclipse sign in the late venous phase was present in 5 patients, mid capillary to late venous phase in 2 patients, late capillary to late venous in 1 patient, and early/mid arterial to late arterial (for 2–3 frames only) in 4 patients. No significant changes after intervention was observed only in 3 patients in whom the eclipse sign was initially visible only in the late venous phase. None of these 3 patients achieved successful thrombosis at 6 months.

Prolonged and earlier appearance of the eclipse sign in comparison to baseline angiography was observed in 9 patients, and completely new appearance from early arterial to late venous was detected in 6 patients. All of these patients achieved successful thrombosis in 6 months (p = 0.001).

Conclusions The presence of eclipse sign alone does not consistently correlate with subsequent aneurysm thrombosis and it can be observed even prior to PED placement. Instead, prolonged and earlier eclipse sign appearance in comparison to baseline angiography is more reliable prognostic factor for prediction of aneurysm thrombosis.

Disclosures R. Raychev: None. S. Tateshima: 2; C; Covidien, Stryker, Reverse Medical, Penumbra, Pulsar Vascular, Blockade. F. Vinuela: None. R. Jahan: 2; C; Covidien, Medina Medical. 3; C; Stryker. N. Gonzalez: None. G. Duckwiler: 2; C; Sequent Medical, Asahi Intecc USA. 6; C; Pipeline Proctor – Covidien.