Inclusion Criteria:  IC 1. Patient whose age is 18 years old or above; IC 2. Patient (or legal representative, where applicable) who understands the study requirements and the treatment procedures and provides written informed consent before any study-specific procedures are performed; IC 3. Patient eligible for the treatment with LVIS™ Evo™ and HydroCoil® Embolic System (HES); IC 4. Patient whose target aneurysm is unruptured or ruptured (> 30 days since occurrence); IC 5. Patient whose target aneurysm size is less than or equal to 12 mm; IC 6. Patient willing to comply with all planned follow-ups and evaluations.  Exclusion Criteria:  EC 1 Patient who has suffered an intracerebral hemorrhage within 30 days prior to the procedure; EC 2. Patient whose target aneurysm is a fusiform aneurysm; EC 3. Patient whose target aneurysm has previously been treated with a stent; EC 4. Patient whose target aneurysm is partially thrombosed; EC 5. Patient whose target aneurysm requires Y stenting; EC 6. Patient whose target aneurysm is associated with an arteriovenous malformation (cAVM), or any other lesion that could lead to hemorrhagic complications; EC 7. Patient who has more than one aneurysm to be treated during the same procedure, (except in case of an adjacent aneurysm that could be treated with the same stent); EC 8. Patient for whom the treatment with another stent than LVIS™ Evo™ or in addition to LVIS™ Evo™ is planned; EC 9. Patient with a planned treatment of other aneurysm in the same vascular territory within 12 months; EC 10. Patient who has a known allergy to contrast agents (that cannot be adequately premedicated) and/or to the study device or procedure-required concomitant medications or procedures (e.g. contraindication to antiplatelet and/or anticoagulants, allergy to Nickel-titanium or contraindication to MRI/MRA or angiography); EC 11. Patient who has one of the following (as assessed prior to the index procedure): Other serious medical illness (e.g., cancer or any severe or fatal comorbidity) with estimated life expectancy of less than the study duration, OR Planned procedure that may cause non-compliance with the protocol or confound data interpretation; EC 12. Patient who is participating or intends to participate in another study that changes the site practice (interventional) within the study time period; EC 13. Pregnant or breastfeeding woman.