ACOART Intracranial ISR Pilot:Intracranial DCB in the 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 procedur…