Citadel Embolization Device Study

Inclusion Criteria:

1. Age is ≥18 and ≤80 years

2. Has a single, unruptured or ruptured target intracranial aneurysm that is suitablefor endovascular treatment. Definition: For the purposes of this study, a rupturedintracranial aneurysm is defined as one with CT/MRI/LP evidence of subarachnoidhemorrhage attributed to the index aneurysm within the last 60 days.

3. Aneurysm morphology is saccular

4. Aneurysm size is between 6-12 mm

5. Has a wide-neck, saccular aneurysm, either bifurcation or sidewall, with a dome toneck ratio <2 or neck ≥4 mm

6. If the target intracranial aneurysm is classified as ruptured, patient must beneurologically stable with a Hunt & Hess Score of 1 or 2.

7. Must be willing to comply with protocol required procedures and follow up

8. Subject or LAR must be willing to sign and date an IRB approved written informedconsent prior to initiation of any screening or study procedures

Exclusion Criteria:

1. Target aneurysm has been previously treated

2. Target aneurysm is in any extradural location, including the extradural cavernoussegment

3. Has vessel characteristics, tortuosity or morphology or unfavorable aneurysmmorphology (e.g., determined from baseline or preprocedure imaging, or which may beevidenced by excessive resistance felt during the procedure) that would precludesafe endovascular access to the target aneurysm necessary for treatment with thestudy device

4. Has significant intracranial atherosclerotic disease or stenosis determined frombaseline or pre-procedure imaging

5. If the target intracranial aneurysm is classified as ruptured, patient isneurologically unstable or has a Hunt & Hess Score of ≥ 3

6. Has a history of intracranial vasospasm not responsive to medical therapy

7. Has undergone coiling or stenting of a non-target intracranial aneurysm within 30days prior to study treatment or has a non-target intracranial aneurysm that isexpected to be treated within 12 months following the treatment of the targetaneurysm

8. Treatment with flow diverting stent implant is anticipated

9. A planned, staged procedure is anticipated

10. Has Moya-Moya disease, arteriovenous malformation(s), arteriovenous fistula(e),intracranial tumor(s), intracranial hematoma(s), any other intracranial vascularmalformation, or any previous major intracranial surgery

11. Has had a recent (within 90 days) ischemic stroke, TIA, or intracranial hemorrhage

12. Has a baseline mRS score ≥2

13. Has a known coagulopathy or is on chronic anticoagulant therapy

14. Is pregnant or intends to become pregnant during the study or is breastfeeding

15. Is concurrently involved in another study that could affect outcomes of IA treatment

16. Has evidence of active cancer, terminal illness, high risk of embolic stroke,unstable atrial fibrillation, significant co-morbidities, major surgery ≤ 30 dayspre-procedure, psychiatric disorders, substance abuse, or a life expectancy of lessthan 5 years

17. Has a contraindication to angiography, radiographic contrast agents, or anymedications that are typically used during the procedure, and any othercontraindications listed in the Investigational DFU

18. Has a confirmed allergy to platinum, tungsten, nickel (e.g. nitinol), or otherelements used in the manufacturing of the investigational device