Intracranial aneurysms (IA) are abnormal outpouchings of cerebral arteries' walls that occur mostly in arteries found in the Circle of Willis and the middle cerebral artery bifurcation with a risk of rupture leading to subarachnoid hemorrhage (SAH) and potentially death. If IA is treated before rupture, survival rates improve dramatically. The IA can be treated with endovascular technique (coiling or stenting). Specifically, the parent artery reconstruction with a flow-diverter stent allows the treatment of a wide range of aneuryms with high rate of aneurysm occlusion. However, during follow-up, up to 15% of FD present deformities, associated with increased morbidity secondary to implant. This phenomenon is not predictable and its mechanism remains unexplained. The objective of this STREAM study is to generate longitudinal clinical and imaging data on the Silk Vista to further evaluate its efficacy and safety in the treatment of unruptured IA, and in particular, to assess and understand the impact of morphological changes over time associated with this device

Intracranial aneurysms (IA) are abnormal outpouchings of cerebral arteries' walls. IA prevalence ranges between 1.8% and 8% in adults, with an approximately equal male/female distribution and a mean age of 50 years at first detection. They predominantly occur in arteries found in the Circle of Willis and the middle cerebral artery bifurcation (85%). The primary concern after discovery of an unruptured IA (UIA) is the risk of rupture leading to subarachnoid hemorrhage (SAH) and potentially death. The aneurysmal SAH has been associated with up to 50% mortality, whereas approximately 30% of survivors are left with severe neurological and/or neurocognitive deficits, resulting in a significant public health burden. Given the evidence that when an IA is treated before rupture, survival rates improve dramatically, identification of aneurysms, specifically those at risk of rupture, and availability of effective treatment strategies, are essential for improving the clinical outcomes of these patients. The IA treatment management includes surgery (neurosurgical clipping has been the gold standard) or endovascular methods. However, over the past decade, the endovascular options to manage IA, ruptured or not, have rapidly evolved, making the treatment of IA less invasive and increasingly more successful. In endovascular technique, a parent artery reconstruction is realized with a flow-diverter stent. Following their specific characteristics, flow diverters (FD) were initially designed to treat giant and large. When comparing FD to the other endovascular techniques (coiling or stenting), FD have been shown to have a higher rate of occlusion for large aneurysms. However, during follow-up, up to 15% of FD present a stenosis that may affect their extremities (known as " fishmouth " stenosis) or their mid-segment (" stent collapse "). The deformities are associated with increased morbidity secondary to implant. This phenomena is not predictable and its mechanism remains unexplained. The DFT (drawn-filled tubing with platinum) technology used for braiding the latest generation of FD stents, including the SILK VISTA stent, may potentially contribute to this phenomenon. Data from an independent and comprehensive evaluation are needed to confirm safety and efficacy in this context. The Silk Vista SDF (BALT, Montmorency, France) is intended for the treatment of IA. The objective of this STREAM study is to generate longitudinal clinical and imaging data on the Silk Vista to further evaluate its efficacy and safety in the treatment of UIA, and in particular to assess and understand the impact of morphological changes over time associated with this device.

Inclusion Criteria:

• Age ≥ 18 and ≤ 80 years old,
• Patient has at least one unruptured intracranial aneurysm intended to be treated with Silk Vista
• Has an untreated or recanalized, unruptured or previously ruptured aneurysm whose rupture occurred >30 days prior to the index procedure
• Able and willing to comply with study procedures including returning to the study site for imaging exams
• Able and willing to give oral informed consent

Exclusion Criteria:

• Any criteria for non- or contraindication to endovascular treatment and/or flow-diverting stent placement (e.g., suspected mycotic aneurysm, including those caused by a left atrial myxoma, systemic bacterial infection, contraindication to antiplatelet drugs (aspirin, clopidogrel/Plavix, ticagrelor, and heparin), local or general anesthesia, allergy to the contrast agent required for treatment by the diversion technique, known severe allergy or hypersensitivity to nickel, titanium, tungsten, or platinum; cost of treatment for an intracranial aneurysm within the last 6 months; and for women, pregnant, or currently breastfeeding)
• Has a true bifurcation aneurysm, defined as an aneurysm (saccular or non-saccular) located at a point of vessel bifurcation
• Has vessel characteristics, such as severe tortuosity, stenosis, or morphology that would preclude safe endovascular access to the target aneurysm necessary for treatment with the study device.
• Presence of intracranial atherosclerotic disease.
• Received previous treatment of the target aneurysm or parent artery where it would interfere with the placement or proper apposition of the device
• Subarachnoid hemorrhage unrelated to a ruptured target aneurysm which occurred within 30 days prior to enrollment
• Intracranial parenchymal hemorrhage occurred within 30 days prior to enrollment
• Major surgery (including previous intracranial implant) occurred within previous 30 days or is planned in the next 6 months after enrollment date
• Has more than one known IA that is anticipated to require treatment within 6 months of the index procedure
• Chronic anticoagulation therapy is ongoing or known coagulopathy exists
• Patient has a serious or life-threatening comorbidity that could confound study results
• Presence of intracranial mass (tumor, except meningioma, abscess, or other infection), non-treated arteriovenous malformation (AVM) in the territory of the target aneurysm
• Participation in any other investigational study which may interfere with collection of valid data under this study or may influence study endpoints Unable to complete study follow up (12 months) due to geographical distance
• Unable to understanding study
• Under legal protection

Patients aged ≥ 18 and ≤ 80 years old, with at least one unruptured intracranial aneurysm intended to be treated with Silk Vista