The objective of the Safety and Efficacy of Endovascular Treatment of Intracranial Aneurysms with Surpass Elite with GUARDian Flow Diverter (GUARD) trial is to evaluate the safety and efficacy of the Surpass Elite with Guardian Flow Diverter System (FDS) in the treatment of unruptured, wide-neck saccular or fusiform, intracranial aneurysms (IAs) located on the internal carotid artery (ICA) or its branches.

The Surpass Elite with Guardian Flow Diverter System is indicated for use in the endovascular treatment of adults (age 18 or above) with unruptured wide-neck saccular or fusiform intracranial aneurysms arising from a parent vessel with a diameter ≥ 3.0 millimeters (mm) and ≤ 6.0 mm and located on the ICA or its branches.

Inclusion Criteria:

1. Age is ≥18 and ≤80 years at the time of consent

2. Has a single unruptured target intracranial aneurysm (IA) of any size with the following characteristics:

   1. Is located on the internal carotid artery or its branches
   2. Has a wide neck (wide neck typically defined as neck width ≥ 4 millimeter (mm), or dome to neck ratio ≤ 2.0) or no discernible neck
   3. Aneurysm is either saccular or fusiform in nature

3. Has a parent vessel diameter ≥ 3.0 mm to ≤ 6.0 mm at the largest diameter

4. There is documented risk-benefit of endovascular treatment that outweighs the risks of intracranial aneurysm rupture during the subject's expected lifetime if left untreated.

Exclusion Criteria:

1. Has an extradural target aneurysm
2. Has a target aneurysm in the posterior circulation
3. Perforator or branch vessel, inclusive of the posterior communicating artery, arises from the target aneurysm body or neck (branches or arteries must arise or connect from the parent vessel separate from the aneurysm or neck to not be excluded from trial)
4. Has a true bifurcation aneurysm, defined as an aneurysm (saccular or non-saccular) located at a point of vessel bifurcation
5. Has vessel characteristics, such as severe tortuosity (cavernous Internal Carotid Artery (cICA) Type IV1), stenosis (>70%), or morphology that would preclude safe endovascular access or proper deployment of the trial device to the target aneurysm
6. Received previous treatment for the target aneurysm or parent artery where it would interfere with the placement or proper apposition of the device
7. Has a medical contraindication to trial or procedure related antiplatelet medications (aspirin, clopidogrel/Plavix, ticagrelor, and heparin), local or general anesthesia, or life-threatening allergy to contrast dye
8. Has a known severe allergy to nickel, chromium cobalt, tungsten, or platinum
9. Patients with heparin hypersensitivity, including patients with a previous incident of Heparin-Induced Thrombocytopenia (HIT).
10. Modified Rankin Score (mRS) assessment is ≥ 3 at pre-procedure exam
11. Presence of unstable neurological deficit (i.e., worsening of clinical condition in the last 30 days prior to the index procedure)
12. Subarachnoid hemorrhage occurred within 30 days prior to the index procedure
13. Major surgery (including previous intracranial implant) either occurred within 30 days prior to the index procedure date or is planned to occur within 120 days following the index procedure date
14. Has more than one intracranial aneurysm (IA) that requires treatment within 12 months after the index procedure
15. Received previous intracranial implant associated with the symptomatic or vascular distribution within the past 84 days prior to treatment date
16. Chronic anticoagulation therapy is ongoing or known coagulopathy exists
17. Has atrial fibrillation with or without pacemaker.
18. Has other known serious concurrent medical conditions such as cardiovascular disease (including recent myocardial infarction [<12 weeks], symptomatic congestive heart failure, or carotid stenosis), kidney failure (>2.0 mg/dl serum creatinine), pulmonary disease, uncontrolled diabetes, progressive neurologic disorders, terminal cancer, vasculitis, high risk of ischemic stroke or recent stroke
19. Has acute life-threatening illness (e.g., acute kidney or heart failure) other than the neurological disease to be treated in this trial
20. Evidence of active infection at the time of treatment
21. Life expectancy is less than 5 years due to other illness or condition (in addition to an intracranial aneurysm)
22. Unable to comply with the trial follow up requirements due to conditions such as dementia or psychiatric problems, active substance abuse, or history of non-compliance with medical advice, as determined by the investigator
23. Pregnant or breast- feeding women or women who wish to become pregnant during the length of trial participation
24. Presence of intracranial mass (tumor, except meningioma, abscess, or other infection), non-treated arteriovenous malformation (AVM) in the territory of the target aneurysm
25. Enrollment in another study involving an investigational product that could confound the outcomes of this trial