OCT in Endovascular Recanalization of Chronic Carotid Artery Occlusion

Chronic carotid artery occlusion is an important cause of ischemic stroke. Even with best medical therapy, patients with symptomatic disease may continue to have recurrent ipsilateral transient ischemic attack or ischemic stroke and may have a substantial burden of cognitive decline. Advances in guidewires, microcatheters, distal protection devices, and endovascular techniques have improved the technical success of CCAO recanalization; however, the overall clinical benefit of endovascular therapy appears highly dependent on patient selection and intra-procedural decision-making. During endovascular recanalization, once the guidewire crosses the occluded segment, the operator often must determine whether intraluminal thrombus, dissection, plaque debris, or other lesions are present. Digital subtraction angiography is essential for lumen and flow assessment but cannot reliably characterize the tissue composition or age of intraluminal filling defects. OCT provides high-resolution intraluminal imaging and may improve thrombus identification and lesion assessment in this setting.

Inclusion Criteria: 1. Age 18-80 years, male or female. 2. Symptomatic chronic carotid artery occlusion, with atherosclerosis as the main etiology and disease duration of at least 3 weeks. 3. Persistent symptoms despite best medical therapy, including ipsilateral TIA or stroke, or imaging evidence of ipsilateral hypoperfusion. 4. Clinically planned endovascular recanalization procedure in which the guidewire successfully crosses the occluded segment. 5. Intra-procedural OCT intraluminal imaging is planned or completed. 6. The operator judges that OCT imaging will not substantially increase immediate rescue risk and that peri-procedural safety observation can be completed. 7. Baseline mRS score 0-2, NIHSS \=6. 8. Target vessel anatomy can support endovascular recanalization and stent therapy if clinically necessary. 9. Written informed consent has been signed before the procedure and includes OCT imaging and follow-up requirements. Exclusion Criteria: * 1.Intra-procedural clinical condition requires immediate rescue treatment, preventing protocol-defined OCT imaging or safety recording. 2.Flow-limiting dissection, vascular rupture, or another serious complication requiring immediate rescue treatment occurs before OCT examination. 3.Non-atherosclerotic etiology, including arterial dissection, moyamoya disease, vasculitis, or radiation-induced vascular injury. 4.Ipsilateral intracranial large vessel occlusion requiring priority treatment. 5.Severe coagulation disorder, including platelet count \2.0. 6.Known contraindication or severe allergy to iodinated contrast, required peri-procedural antithrombotic medication, or OCT-related flushing or contrast procedures. 7.Large cerebral infarction, defined as ASPECTS \70 mL. 8.Severe target vessel calcification or tortuosity such that the OCT catheter is not expected to pass safely or the recanalization risk is judged to be extremely high. 9.eGFR \