International, non-randomized, European , multicenter, observational study to collect data for the treatment of intracranial aneurysms with OPTIMA coils system to further document its safety and efficacy

Inclusion Criteria:

1. Patient with small or large intracranial aneurysm, ruptured or unruptured, intended to be selectively treated with the OPTIMA coil system. Patients with recanalized aneurysms previously treated with coils exclusively are also eligible. Balloon and stent assisted coiling are allowed at index procedure.
2. In case of multiple aneurysms, patient can be included when only 1 aneurysm is treated during the procedure and none of the other aneurysms are treated up to 30 days post-procedure
3. Patient older than 18 years
4. Patient who has been informed of the study and has signed an informed consent form where applicable according to local regulations.

Exclusion Criteria:

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1. giant aneurysms (>25 mm)
2. recanalized aneurysms initially treated with stent or flow diverter (Only aneurysms initially treated with coils are eligible)
3. aneurysm treated with parent artery occlusion
4. dissecting or fusiform aneurysms
5. aneurysms associated with an arteriovenous malformation
6. aneurysm intended to be treated with flow diverter or flow disrupter during the procedure
7. aneurysm intended to be treated in a staged procedure
8. intracranial tumor (except meningioma)
9. Any condition or any situation that would prohibit the patient from coming to the investigational center for the follow-up, as requested according to sites current practice.