Please select the eligibility criteria that correspond to the clinical trial below.
Title: Imaging Collaterals in Acute Stroke
Brief Summary: Stroke is caused by a sudden blockage of a blood vessel that delivers blood to the brain. Unblocking the blood vessel with a blood clot removal device restores blood flow and if done quickly may prevent the disability that can be caused by a stroke.

However, not all stroke patients benefit from having their blood vessel unblocked.

The aim of this study is to determine if special brain imaging, called MRI, can be used to identify which stroke patients are most likely to benefit from attempts to unblock their blood vessel with a special blood clot removal device. In particular, we will assess in this trial whether a noncontrast MR imaging sequence, arterial spin labeling (ASL), can demonstrate the presence of collateral blood flow (compared with a gold standard of the angiogram) and whether it is useful to predict who will benefit from treatment.


Options:
A: Inclusion Criteria A. Clinical (Heterogeneous sampling frame)

1. Acute ischemic stroke
2. Age 18 or greater
3. Onset (last-seen-well) time to randomization time \< 12 hours.
4. Disabling stroke defined as a baseline NIHSS \> 5 at the time of randomization.
5. Pre-stroke (24 hours prior to stroke onset) independent functional status in activities of daily living with modified Barthel Index \> 90. Patient must be living in their own home, apartment or seniors lodge where no nursing care is required.

   B. Imaging (Homogeneous target population)
6. Confirmed symptomatic intracranial occlusion, based on single phase, multiphase or dynamic CTA, at one or more of the following locations: Carotid T/L, M1 MCA, or M1-MCA equivalent (2 or more M2-MCAs). Anterior temporal artery is not considered an M2.
7. Non-contrast CT and CTA for trial eligibility performed or repeated at ESCAPE stroke center with endovascular suite on-site.
8. Endovascular treatment intended to be initiated (groin puncture) within 60 minutes of baseline non-contrast CT with target baseline non-contrast CT to first recanalization of 90 minutes.
9. Signed informed consent or appropriate signed deferral of consent where approved.

Exclusion Criteria

1. Baseline non-contrast CT reveals a moderate/large core defined as extensive early ischemic changes of ASPECTS 0-5 in the territory of symptomatic intracranial occlusion.
2. Other confirmation of a moderate to large core defined one of three ways:

   1. On a single phase, multiphase or dynamic CTA: no or minimal collaterals in a region greater than 50% of the MCA territory when compared to pial filling on the contralateral side (multiphase/dynamic CTA preferred) OR
   2. On CT perfusion (\>8 cm coverage): a low CBV and very low CBF ASPECTS \<6 AND in the symptomatic MCA territory OR
   3. On CT perfusion(\<8 cm coverage): a region of low CBV and very low CBF \>1/3 of the CTP imaged symptomatic MCA territory.
3. Groin puncture is not possible within 60 minutes of the first slice of non-contrast CT acquisition (please note that if CTP is performed it should be done after CTA).
4. No femoral pulses or very difficult endovascular access that will result in a non-contrast CT-to-recanalization time that is longer than 90 minutes, or will result in an inability to deliver endovascular therapy.
5. Pregnancy; if a woman is of child-bearing potential a urine or serum beta HCG test is positive.
6. Severe contrast allergy or absolute contraindication to iodinated contrast.
7. Suspected intracranial dissection as a cause of stroke.
8. Clinical history, past imaging or clinical judgment suggests that the intracranial occlusion is chronic.
9. Patient has a severe or fatal comorbid illness that will prevent improvement or follow-up or that will render the procedure unlikely to benefit the patient.
B: Inclusion Criteria:

1. Age 18 and older (i.e., candidates must have had their 18th birthday)
2. NIHSS ≥8 at the time of neuroimaging
3. Presenting or persistent symptoms within 6 hours of when groin puncture can be obtained
4. Neuroimaging demonstrates large vessel proximal occlusion (distal ICA through MCA bifurcation)
5. The operator feels that the stroke can be appropriately treated with traditional endovascular approaches (the ADAPT approach or conventional first-line stent retriever approach)
6. Pre-event Modified Rankin Scale score 0-1
7. Non-contrast CT/CTA for trial eligibility performed or repeated at treating ADAPT stroke center.
8. Consenting requirements met according to local IRB

Exclusion Criteria:

1. Patient is more than 6-hours from symptom onset
2. Rapidly improving neurologic examination
3. Absence of large vessel occlusion on non-invasive imaging
4. Presence of an existing or pre-existing large territory infarction
5. Known or suspected pre-existing (chronic) large vessel occlusion in the symptomatic territory
6. Absent femoral pulses
7. Excessive vascular access tortuosity that will likely result in unstable access platform.
8. Pregnancy; if a woman is of child-bearing potential a urine or serum beta HCG test is positive.
9. Severe contrast allergy or absolute contraindication to iodinated contrast.
10. Clinical history, past imaging or clinical judgment suggests that the intracranial occlusion is chronic.
11. Patient has a severe or fatal comorbidities that will likely prevent improvement or follow-up or that will render the procedure unlikely to benefit the patient.

Head CT or MRI Scan Exclusion Criteria

* Presence of blood on imaging (subarachnoid hemorrhage (SAH)), intracerebral hemorrhage (ICH), etc.)
* High density lesion consistent with hemorrhage of any degree
* Significant mass effect with midline shift
* Core infarct lesion volume \>50 cc.
* Large (more than 1/3 of the middle cerebral artery) regions of clear hypodensity on the baseline CT scan or ASPECTS of \< 7; Sulcal effacement and/or loss of grey-white differentiation alone are not contraindications for treatment.
C: Inclusion Criteria

1. Age 18 and older
2. Clinical diagnosis of ischemic stroke and an associated score on the NIHSS of 5 or more points
3. Planned to undergo (or has undergone) intra-arterial (IA) thrombectomy and/or thrombolysis for acute hemispheric stroke. (Either as primary therapy or as adjuvant therapy following intravenous tPA treatment)
4. Planned to undergo or has undergone an MR brain scan including MR perfusion imaging (ASL \& bolus PWI) and MR angiography of the circle of Willis prior to IA therapy
5. Intra-arterial thrombectomy can be started within 90 minutes of completion of the MR perfusion scan and within 24 hours of symptom onset (Start of IA therapy is defined as the time of insertion of the femoral artery sheath; Time of brain scan is defined as the time that the scan is completed)
6. Able to obtain informed consent

Exclusion Criteria

1. Any pre-existing illness resulting in a modified Rankin Scale Score of 2 or higher prior to the qualifying stroke
2. Creatinine clearance \< 40 ml/min based on the NIDDK four-variable MDRD method (non-weight based)
3. Documented allergy to MR contrast agent
4. MRI contraindications (pacemaker, etc.)
5. Pregnancy
D: Inclusion Criteria:

* Age \> 18 years with no upper age limit.
* Cerebral infarction in the anterior circulation
* Occlusion of the anterior circulation proven by CT angiography or MR angiography
* With or without previous Intravenous thrombolysis
* Start of thrombectomy procedure within 6 hours of symptoms onset.
* Patient expresses verbally his non-opposition to be enrolled in the study ; in case patient cannot communicate, verbal non-opposition is obtained from his close / trusted person

Exclusion Criteria:

* Absence of indication for thrombectomy
* Cons-indication for thrombectomy
* Presence of cerebral infarction of the posterior circulation
* Occlusion of the cervical carotid artery
* Allergy to x-ray contrast products
* Patient was bedridden or using a wheelchair most of the day (pre-event modified Rankin Scale score \> 3) prior to stroke
* Pregnancy or breastfeeding
* Patient under legal protection
* No affiliation to health insurance

Secondary exclusion criteria

- Lack of access route for catheterization

Answer: C