Carotid artery stenting(CAS) and endarterectomy(CEA) are both important treatment strategy for patients with ICA (internal carotid artery) stenosis. Three dimensional pseudo-continuous arterial spin labeling (pCASL) is a noninvasive perfusion imaging modality to detect reperfusion for recanalization therapy. And it provides information about absolute CBF (ml 100 g-1 tissue min-1) at the brain tissue level. The aim of the present study was to evaluate the series hemodynamic changes in patients who had conducted CAS or CEA by using 3D pseudo-continuous arterial spin labeling (pCASL) to explore the potential pattern of CBF alternation and thus to improve the prevention strategy for hyperperfusion syndrome.

Patients:

Patients with unilateral severe internal carotid artery (ICA) stenosis of stroke eligible were enrolled who underwent CAS vs CEA.All patients underwent previous scan in 7 days before CAS and CEA and consecutive scan once per 24 hours after CAS and CEA.

Baseline characteristics of patients were recorded including age,gender, hypertension, hypercholesterolemia, diabetes melitus, smoking, obesity, qualifying stroke event.

Protocols:

MRI scan protocols T2 weighted image,T1 weighted image,diffusion weighted image(DWI),fluid-attenuated inversion recovery (FLAIR),arterial spin labeling(ASL) with Post labeling delay (PLD) of 2.0s,Territory ASL(TASL)(PLD=2.0s),3-dimensional Fast Spoiled Gradient Echo(3D-FSPGR).

Imaging evaluation：

1. Pseudo-continuous arterial spin labeling (pCASL) with post labeling delay (PLD) of 2.0s evaluation of cerebral blood flow in target downstream territory.
2. FLAIR hyperintensity vascular sign.
3. Collateral pattern assessment by Territorial ASL(TASL) (PLD=2.0s).

Treatment strategy:

Patients were randomly treated by CEA(carotid endarterectomy) or CAS(carotid artery stenting).

Follow up:

Patients were followed up every 24 hours after treatment procedure, and would have a repeat MRI scan after 3 months, 6 months and 1 year.

Inclusion Criteria:

• informed patient's consent for ICA stenting or endarterectomy
• lack of contraindications to MRI
• Symptomatic, unilateral ICA stenosis 70-99%;irrelevant stenosis <50% of contralateral ICA
• TIA or stroke - within 360 days

Exclusion Criteria:

• Intracranial hemorrhage
• Informed consent not obtained
• Common exclusion for MRI such as patients with claustrophobia
• Patients with poor imaging quality（Poor imaging quality mainly defined as the image cannot be applied to future analysis on account of severe motion artifacts appeared in conventional MRI and mistakes in the MRI process by accident factors which cannot to be applied to future analysis）
• Bilateral internal carotid artery occlusion

Symtomatic patients with unilateral severe internal carotid artery (ICA) stenosis.