OCT in Endovascular Recanalization of Chronic Carotid Artery Occlusion

OCT is one of the highest-resolution intravascular imaging modalities, with axial resolution in the range of approximately 10-20 um. Compared with intravascular ultrasound, OCT can more clearly demonstrate vessel wall layering, plaque components, thrombus surface morphology, signal attenuation, and intraluminal structural detail. In carotid intervention, published clinical experience suggests that OCT may help define thrombus boundaries, characterize thrombus morphology, guide stent landing zones, inform use of protection devices, and support peri-procedural antithrombotic decisions.

The clinical value of OCT thrombus typing remains incompletely established. Coronary OCT studies have reported good discrimination of thrombus type using image attenuation, backscatter, and grayscale parameters, whereas other studies comparing acute OCT findings with histopathology have not confirmed reliable prediction of thrombus composition or freshness. These conflicting data indicate that OCT thrombus classification should be validated prospectively within the specific clinical context of CCAO recanalization rather than extrapolated from coronary studies or isolated case reports.

Inclusion criteria

• Age 18-80 years, male or female.
• Symptomatic chronic carotid artery occlusion, with atherosclerosis as the main etiology and disease duration of at least 3 weeks.
• Persistent symptoms despite best medical therapy, including ipsilateral TIA or stroke, or imaging evidence of ipsilateral hypoperfusion.
• Clinically planned endovascular recanalization procedure in which the guidewire successfully crosses the occluded segment.
• Intra-procedural OCT intraluminal imaging is planned or completed.
• The operator judges that OCT imaging will not substantially increase immediate rescue risk and that peri-procedural safety observation can be completed.
• Baseline mRS score 0-2, NIHSS <=15, and ASPECTS >=6.
• Target vessel anatomy can support endovascular recanalization and stent therapy if clinically necessary.
• 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 <80 x 10^9/L or INR >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 <6 or DWI infarct volume >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 <30 mL/min or severe hepatic dysfunction. 10.Life expectancy <12 months. 11.Pregnancy or lactation. 12.Current participation in another conflicting clinical study that may affect outcome assessment.