This project is aimed at developing new MR imaging capabilities for depicting the anatomy of intracranial aneurysms, and to elucidate the hemodynamics within these entities. Successful completion of this project will lead to more robust, reliable and time-efficient MRI methods for acquiring high resolution 3D angiograms and fully 7D flow measurements within the vasculature. This will create a systematic and methodical approach to the determination of anatomy and function in intracranial aneurysms and will provide important new guidance to clinicians as they develop strategies to treat these disorders. The specific aims of this project are therefore: 1) to use flow phantoms with a range of complexity to determine the most suitable imaging approach for capturing time-resolved information on velocity fields and for evaluating the flow lumen, using the full capabilities of current MR hardware and software. 2) We aim to develop and evaluate tools for display, post-processing and analysis of geometric and high dimensional, hemodynamic data from different time points and modalities; and 3) Test the optimal techniques developed in Aims 1 and 2 in patient studies, and evaluate the ability to monitor changes in anatomy and physiology over time. Current methods for acquiring MR angiography and velocity determination have been developed in the clinical setting on human studies where it is difficult to perform systematic and repeated studies. Those developments also lack a true gold standard and comparisons between MR measurements and gold standard techniques have typically been qualitative. Patient-derived models that replicate in vivo flow conditions will permit the determination of the limits of current methods, and allow for selection of the most suitable approach. Accurate maps of locations of structural changes that can be linked to the hemodynamic forces acting at those locations in aneurysms will provide information that will provide an insight on the progression of aneurysmal disease on a patient-specific basis. Relevance to public health: This proposal aims to develop MR methods for assessing the structure of aneurysms in the brain and for measuring blood flow patterns within those aneurysms. The availability of a robust and reliable method for non-invasively assessing structure and function in these territories will permit clinicians to effectively evaluate patients with these diseases, sparing them the associated risks of arterial catheterization. In addition, the ability to non-invasively determine blood flow patterns in intracranial aneurysms should provide new insights into the underlying physiology that causes some aneurysms to remain stable, and others to grow, resulting in profound symptoms or rupture with a high likelihood of devastating cerebral injury or death.