Quantitative ASL MR angiography and perfusion imaging for cerebral revascularization

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PROJECT SUMMARY/ABSTRACT Cerebrovascular disease is one of the leading causes of death and disability worldwide. Cerebral revascularization, especially surgical revascularization, has evolved as an effective surgical therapy for the management of chronic cerebrovascular diseases such as moyamoya disease, complex aneurysms, and selected carotid steno-occlusive disease to improve the cerebral hemodynamics and reduce the risk of stroke. Nonetheless, optimal surgical planning is still unclear as a variety of revascularization techniques can be considered. To date, the choice of revascularization strategy is primarily based on the subjective interpretation of flow demands in the at-risk territory. This results in a variable, subjective clinical practice that places patients at risk for hemodynamics-related postoperative complications, significantly impacting the clinical outcomes. A segmented and quantitative characterization of cerebral hemodynamics pre- and post-revascularization is necessary to objectify flow requirements, standardize and improve patient care. However, none of the existing clinical imaging modalities are able to provide high spatiotemporal resolution angiographic images with quantitative hemodynamic information from individual arterial segments without contrast agents. Arterial spin labeling (ASL) possesses appealing features that allow for the assessment of both perfusion and angiography quantitatively. Building upon our successful track record on the development of ASL 4D MRA as well as ASL perfusion imaging, the goal of the present project is to develop and evaluate an easily-carry-out noninvasive ASL suite consisting of advanced 4D MRA and perfusion territorial mapping to quantitively assess cerebral hemodynamics from individual arteries and downstream tissue pre and post-cerebral revascularization. In Aim 1, we will develop and optimize a novel rapid high spatiotemporal resolution 4D MRA technique (<5minutes). In Aim2, we will develop and validate post-processing algorithms for cerebral hemodynamic quantification and vascular territories with 4D MRA and random vessel-encoded ASL. By leveraging the rich clinical resource from the USC Revascularization Center, in Aim 3, we will quantitively evaluate perioperative hemodynamics on patients who undergo cerebral revascularization and study the association of revascularization-related hemodynamic change with clinical outcomes. The successful completion of this project will lead to a robust, noninvasive, flexible, and quantitative ASL MRI suite within 10 min scan time that is ready to be incorporated into clinical MRI settings. The proposed technique can be highly valuable as a potential imaging tool for the quantitative evaluation of flow demands in cerebral revascularization.