The purpose of the study is to evaluate the safety and feasibility of drug coated balloon in treatment of intracranial in-stent restenosis.

This study is a prospective, multi-center, randomized controlled trial using drug coated balloon versus uncoated PTA balloon in treatment of intracranial in-stent restenosis.

Inclusion Criteria:

• 18 to 80 years of age
• Confirmed by DSA: in-stent restenosis (ISR) at intracranial segment of internal carotid artery, middle cerebral artery, basilar artery and vertebral artery; ISR is defined as >50% stenosis within or immediately adjacent (within 5 mm) of the implanted stent and >20% absolute luminal loss
• presence of ISR associated ischemic stroke or transient ischemic attacks even with medical treatment and strict control of risk factor
• asymptomatic ISR with severe hypoperfusion in the ISR territories, confirmed by a cerebral blood flow decrease of ≥30% when compared with the perfusion on the contralateral side for anterior circulation lesions or the anterior circulation territory for posterior circulation lesions on CT perfusion, and/or by an American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) Collateral Flow Grading System score <3 on DSA.
• the diameter of target vessel is 2.0-4.5mm
• there is only one intracranial ISR lesion per subject
• baseline mRS score ≤2
• Voluntarily participate in this study and sign the informed consent form

Exclusion Criteria:

• Patients with stroke within 2 weeks before procedure;
• any history of brain parenchyma or other intracranial subarachnoid, subdural or extradural hemorrhage in the past 30 days.
• Those who have received thrombolysis within 24 hours before procedure;
• Deterioration of neurological function within 24 hours before procedure (defined as NIHSS score increased by ≥ 4 points over the baseline)
• patients with thrombus in target vessels.
• in addition to ISR lesions, there are other primary intracranial lesions that need endovascular treatment.
• Major surgery (including open femoral, aortic or carotid artery surgery) is planned within the past 30 days or within 90 days.
• patients with renal artery, iliac artery and cardiac coronary artery requiring simultaneous intervention.
• Combined with intracranial tumors, aneurysms or intracranial arteriovenous malformations.
• Cardiac stroke or potential cardiogenic thromboembolism, with any of the following cardiogenic embolism causes: chronic or paroxysmal atrial fibrillation, mitral valve stenosis, mechanical valves, endocarditis, intracardiac thrombus or implant, dilated cardiomyopathy, spontaneous acoustic imaging of the left atrium;
• patients with myocardial infarction within 6 weeks before procedure.
• those who cannot tolerate general anesthesia due to insufficiency of heart, lung and other important organs.
• patients with known severe hepatic and renal dysfunction.
• patients with hemoglobin < 100g / L, platelet count < 100,000 / mm3, INR > 1.5or with uncorrectable factors leading to bleeding.
• patients who cannot receive dual antiplatelet therapy due to existing diseases or who are tested to be tolerant to dual antiplatelet therapy.
• Patients with known severe allergies or contraindications to heparin, paclitaxel, contrast agents and other related intravascular treatment drugs
• current alcohol or drug abuse, uncontrolled severe hypertension (systolic blood pressure > 180mmHg or diastolic blood pressure > 110mmHg).
• Life expectancy < 1 year.
• pregnant or lactating women.
• patients who are unable to complete follow-up due to cognitive, emotional disorders or mental illness.
• Patients who are participating in other drug/device clinical trials and have not completed all follow-ups required by the programme;
• According to the judgement of the investigator, other situations that are not suitable for enrollment