Pipeline TM embolization device launched to China in 2014, and has been widely used to treat large width IA. Therefore, it is necessary to collect and analysis the clinical data to evaluate effectiveness and safety of its usage in Chinese population, and this may guide the clinical practice and meet the clinical needs better.

Recent years, the rapid development of endovascular treatment, especially the introduction of blood flow diverter device, has led to a new step in the treatment of intracranial aneurysms. It is different from usual treatment concept, blood flow diverter device's innovation is guiding to its parent artery reconstruction by cutting into the blood flow velocity and flow rate to the IA, and, promote the forming of aneurysm cavity thrombosis and the Neointima growth of IA's neck, so that to achieve aneurysm treatment.

A number of multi-center clinical studies on Pipeline embolization devices (PED, Ev3 Company/Medtronic, USA) have been conducted in North America and Europe recently. Becske etc reported the result of one multi-center prospective clinical trial of North America (PUFS), the PED treats the complicated intracranial internal carotid artery aneurysm. At the time of 180 days, 1 year, 3 years follow-up, the complete occlusion rate were 73.6%, 86.8% and 93.4% respectively. O 'kelly etc. the study showed that the rate of subtotal occlusion over 1 year follow-up of PED treatment for complex intracranial aneurysms was 90%. Many studies have confirmed the effectiveness of PED in the treatment of complex intracranial aneurysms.

The main motivation to innovate the blood flow diverter device is to use it to treat some large or giant aneurysms, fusiform aneurysm which can't be treated well by ordinary interventional embolization methods. So, in the initial stage of the application, its indications are mainly focus on the large or giant aneurysms located in the internal carotid artery before the origin of the posterior communicating artery. In recent years, the blood flow diverter devices were already used to treat many kinds of IA in almost all parts of the brain, different sizes and with pathological changes, such as dissecting aneurysms and vesicular aneurysms.

Although there was already much clinical research evidence which proved the efficacy and safety of PipelineTM 's treatment to the aneurysm as the embolization device, but these data are all from the foreign population, there is still no published clinical evidence of large sample size clinical study of Chinese population. Pipeline has been widely used to treat large width IA. Therefore, it's meaningful to evaluate effectiveness and safety in Chinese population, and this may guide the clinical practice and meet the clinical needs better.

Inclusion Criteria:

• Patients accepting to participate the study
• Patients treated with Pipeline

Exclusion Criteria:

• Patients treated by parent vessel occlusion
• Patients treated by other stent
• Patients lacking 3-dimensional aneurysm images or the images not satisfied the simulation

The trial is intended to conduct in 13 centers in China. The sample size of this study was calculated based on the embolization rate of aneurysm. According to the existing overseas research data, we assume that the one-year embolization rate of Pipeline treatment for aneurysms is about 70%. Under the condition that the allowable error is 10% and the inspection level is 0.05, 162 cases are needed in this study. Considering the heterogeneity of different centers, the further expanded sample size is 200 cases.