To evaluate the efficacy and safety of catheter-based thrombectomy for reperfusion by removing a thrombus in a cerebral blood vessel in patients with acute cerebral infarction (within 8 hours after onset), in whom intravenous administration of tissue plasminogen activator (t-PA) is not indicated or reperfusion cannot be achieved by intravenous t-PA administration.

Inclusion Criteria:

1. Patients with neurological disorders caused by blood vessel occlusion associated with acute cerebral infarction
2. Patients who can receive treatment within 8 hours after onset of symptoms of acute cerebral infarction
3. Patients in whom intravenous administration of t-PA is not indicated or reperfusion cannot be achieved by intravenous t-PA administration
4. Patients who have accessible occlusion of the middle cerebral artery (M1 or M2 to 3), basilar artery, vertebral artery, posterior cerebral artery (P1 or P2), anterior cerebral artery (A1 to 2), or intracranial internal carotid artery (pre-procedure TICI score, 0 or 1) as determined by angiography
5. Patients with an NIHSS score of 8 to 30
6. Patients with an mRS score of 0 to 2 before onset
7. Patients aged between 20 and 85 years (at the time of informed consent)
8. Patients who are able to provide written consent (signature) or whose legally acceptable representative (a person with parental authority, spouse, guardian, and an individual legally responsible for his/her custody) can provide written consent (signature)

Exclusion Criteria:

1. Patients who manifest the following:

   • Carotid artery dissection
   • Vasculitis
   • An angulated vessel, making it difficult to guide an investigational device
   • Significant (>50%) stenosis, making it difficult to guide an investigational device
   • Acute intracranial hemorrhage
   • Mass lesion or intracranial tumor
   • Widespread early ischemic changes revealed by CT or MRI

2. Patients who have two or more different major cerebrovascular occlusions requiring treatment

3. Patients with an allergy to contrast agents or who cannot receive them or those who have a serious metal allergy

4. Patients who received heparin within 48 hours and have Partial Thromboplastin Time (PTT)/Activated Partial Thromboplastin Time (APTT) > twice the upper limit of normal

5. Patients with known bleeding tendencies or coagulation deficiency or who have received oral anticoagulants (such as warfarin), and who have (PT-) International Normalized Ratio (INR) >3

6. Patients with platelet count <30,000 /mm3

7. Patients with blood glucose levels <50 mg/dL

8. Patients with uncontrolled hypertension (systolic BP >185 mmHg and diastolic BP >110 mmHg)

9. Patients with expected life expectancy <90 days

10. Female patients who are pregnant or breast feeding

11. Patients who are participating in clinical trials of drugs or medical devices

12. Patients disqualified from participation in the study by the investigator (sub-investigator) due to reasons other than the above