Investigation of Brain Blood Flow Changes in Acute Ischemic Stroke Patients After Successful Endovascular Thrombectomy

Introduction: Endovascular thrombectomy (EVT) is an effective treatment strategy to mitigate the ischemic tissue damage caused by the acute cerebral large-vessel occlusion. However, in clinical practice, nearly half of the patients do not experience adequate neurological improvement despite successful recanalization - a phenomenon termed reperfusion failure or clinically ineffective reperfusion. Given the clinical relevance of this phenomenon and the absence of a standardized imaging diagnostic method to identify it, our project aims to explore the potential role of blood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR) as novel imaging biomarker for studying reperfusion failure. Study population: Adult patients with acute ischemic stroke of the ICA, MCA or with tandem occlusion who have undergone a successful recanalization, described as mTICI score ≥2b. Objective(s): Primary objective: to longitudinally observe blood flow changes derived from BOLD-CVR imaging following successful endovascular thrombectomy in patients with large-vessel occlusion acute ischemic stroke (LVO-AIS) during the early post-treatment phase and assess their association with clinical outcome 90 days post-EVT. Secondary objective: to compare BOLD-CVR findings with those obtained from the clinical standard dynamic susceptibility contrast (DSC) MR perfusion imaging acquired in the same examination session as well as other imaging techniques included in the standard post-treatment imaging protocol at our institution. Outcomes: Clinical outcomes: * 90-day functional outcome. * Functional outcome at hospital discharge. * Neurological deterioration during hospitalization. * Radiologically confirmed haemorrhagic transformation within the reperfused tissue. * Radiologically confirmed infarct lesion progression within the reperfused tissue. * Additionally, DSC MR perfusion imaging parameters and other standard hemodynamic imaging parameters will be considered as imaging outcomes Study design: Single-center prospective observational cohort study Measurements and procedures: Included patients will undergo a total of 3 BOLD-CVR examinations: 72 hours, 7 days, and 90 days after EVT. Participation in the final examination will mark the end of the subject's involvement in the study. Clinical outcomes will be prospectively collected as per established institutional patient management protocols: during hospitalization, at discharge, and at the cerebrovascular outpatient clinic at 3 months. Number of Participants: Target sample size: 100 patients Given the observational study design and exploratory nature of this project, no sample size calculation can be performed. The provided target sample size (N = 100) has been estimated considering the inclusion of as many consecutive subjects as possible. Study period: 2.5 years The investigators aim to enroll a target sample size of 100 patients over a period of 2.5 years. This translates to an inclusion of 3-4 patients per month, with the last three months allocated for the follow-up of the last included patients. Study Centre: Clinical Neuroscience Center, Department of Neurosurgery, University Hospital Zurich Statistical Considerations: The association between BOLD-CVR findings and clinical outcomes will be investigated using regression analyses.