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Inclusion criteria:

Participants meeting all the following inclusion criteria will be included:

Preoperative inclusion criteria:

* Presence of unruptured aneurysms in the internal carotid artery (from the petrous segment to the distal end) or vertebral artery identified by digital subtraction angiography (DSA), computed tomography angiography (CTA), or magnetic resonance angiography (MRA) prior to surgery, wide-neck (neck width greater than or equal to \[\>=\] 4 millimeters \[mm\] or dome-to-neck ratio less than \[\<\] 2) saccular or fusiform aneurysms, and the parent artery diameter must be \>= 2.0 mm and less than or equal to \[\<=\] 6.0 mm
* Participants and/or their authorized representatives understand the purpose of the study, and are willing to voluntarily participate in the study and sign the informed consent form (ICF)
* Prior to enrollment, a clinical decision has already been made to use the choydar flow-directed mesh stent
* Participants who are willing and able to return for all follow-up visits as required by the study protocol

Intraoperative inclusion criteria:

\- Presence of unruptured aneurysms in the internal carotid artery (from the petrous segment to the distal end) or vertebral artery identified by DSA during the procedure, wide-neck (neck width \>= 4 mm or dome-to-neck ratio \<2) saccular or fusiform aneurysms, and the parent artery diameter must be \>= 2.0 mm and \<= 6.0 mm

Exclusion criteria:

Participants meeting any of the following exclusion criteria will be excluded:

* Participants with anatomy are unsuitable for flow diverter passage or placement or lesions unsuitable for flow diverter delivery and deployment (for example, the lesion vessel is excessively tortuous or tiny, the flow diverter cannot reach the lesion site, stenosis exists in the target vessel of recurrent aneurysm, or the flow diverter is not completely deployed)
* Participants who are allergic to contrast media
* Participants who are allergic to nickel-titanium alloy or platinum-tungsten alloy
* Participants who are contraindicated for antiplatelet and/or anticoagulant therapy
* Participants with active bacterial infections
* Participants who are confirmed positive pregnancy (for example, via test or oral communication) according to the site-specific standard of care
* Participants who are currently participating in an investigational (drug, device, etc.) clinical study that may confound the study endpoints (excluding observational, natural history, and/or epidemiological studies that do not require interventions)

• Chenzhou, China
• Guangzhou, China
• Nanjing, China
• Nanjing, China
• Nanyang, China
• Taiyuan, China
• Wuhu, China
• Zhengzhou, China