Arterial spin labeling MRI in patients undergoing carotid artery revascularization: a systematic review of the hemodynamic changes and clinical implications

Arterial spin labeling (ASL) MRI is a non-invasive imaging modality that measures cerebral blood flow (CBF) without the need for contrast agents or radiation, offering insights into hemodynamic changes. Carotid revascularization procedures, carotid endarterectomy and carotid artery stenting, aim to improve cerebral perfusion and reduce the risk of ischemic events. This study explores ASL's clinical potential in assessing CBF changes in carotid stenosis patients prior to revascularization procedures. A systematic review was conducted following PRISMA guidelines to identify studies that utilized ASL in patients undergoing carotid revascularization. Searches were performed in the MEDLINE/PubMed and Web of Science databases. Extracted data included patient demographics, ASL acquisition parameters, perfusion analysis methods, and study findings related to ASL results. Twenty studies involving 710 patients were included. Preoperative ASL consistently identified perfusion deficits ipsilateral to stenosis, which improved post-revascularization, particularly in eloquent brain regions. After revascularization, CBF increase was greatest in patients with severe baseline deficits and smaller in those with prior strokes. ASL metrics predicted post-procedural cerebral hyperperfusion (CH), though protocol variability influenced results. Visual assessment methods based on arterial transit artifacts (ATA) emerged as practical tools for hyperperfusion risk prediction without requiring extensive post-processing. ASL MRI is a valuable tool for assessing hemodynamic changes in carotid artery stenosis and predicting treatment outcomes, particularly the risk of hyperperfusion. Its non-invasive nature and ability to evaluate collateral flow enhance its clinical value. Question Can arterial spin labeling (ASL) MRI reliably assess cerebral blood flow changes in patients with carotid stenosis undergoing revascularization, improving decision-making regarding risks and outcomes? Findings ASL detects pre-treatment perfusion deficits, quantifies post-revascularization blood flow increases, predicts hyperperfusion risk, and assesses collateral flow in carotid stenosis patients undergoing endarterectomy or stenting. Clinical relevance ASL MRI provides a non-invasive method to evaluate cerebral perfusion in carotid stenosis, aiding in risk assessment for cerebral hyperperfusion syndrome and optimizing treatment strategies by preoperatively assessing collateral circulation and post-treatment cerebral blood flow recovery.