Intracranial aneurysms present a formidable risk of death or devastating injury either from mass effect or hemorrhage. Aneurysms are detected with a broad range of sizes on first presentation. However, little is known about the rate of progression of aneurysms over time. It has long been suspected that hemodynamic forces play an important role in the genesis and rupture of aneurysms, but there is, to our knowledge, no literature that demonstrates which hemodynamic descriptors of an aneurysm are predictive of future growth. Recent results from the International Study of Unruptured Intracranial Aneurysms demonstrate that the risk of attempting a repair of aneurysms smaller than 7 mm in diameter exceeds the benefit from that intervention. There is now, therefore, a group of patients with saccular intracranial aneurysms who are not being treated, and who can be followed by non-invasive imaging. These patients are part of a broader group of patients with aneurysms of the intracranial circulation for whom there are no safe and effective interventions. The goal of this project is to monitor such patients on a bi-annual basis with non-invasive Magnetic Resonance Imaging. Using boundary values (geometric and velocity) obtained from patient-specific in-vivo imaging, Computational Fluid Dynamics (CFD) simulations will be performed to determine the hemodynamic conditions in each aneurysm. Progression over time in aneurysm lumen volume and/or volume of intralumenal thrombus will be measured from co-registered serial imaging studies. A relationship between different candidate hemodynamic variables and observed aneurysm growth will be sought. Specifically, we hypothesize that, specifying a low wall shear stress threshold value, the larger the surface area is with wall shear stress below that threshold value the greater will be the increase in aneurysm volume over time. In addition to using the standard methodology already established, we will develop new imaging capabilities, and will implement more comprehensive measurements of flow velocities throughout the vascular territory of interest. Our CFD methods will be extended to model non-Newtonian effects, and the in-vivo velocity measurements will be used to select which model is most suitable. As these new tools become available they will be used to improve the accuracy of our methods. This project represents an effort in translational research directed at an important component of neurovascular disorders. Public Health Relevance: This study will determine the relationship between growth of intracranial aneurysms and hemodynamic forces. That information will be used to guide clinicians as to what interventional treatments might be considered, and when they might best be implemented.

Public Health Relevance

This project proposes to examine the influence that forces exerted by flowing blood have on the progression of aneurysms in the brain. The project will use non-invasive MR imaging to monitor changes in aneurysm anatomy over time and numerical simulations to calculate the hemodynamic forces. The project will provide insight into the underlying mechanisms of aneurysm progression and could help in guiding treatment for this devastating condition.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Medical Imaging Study Section (MEDI)
Program Officer
Jacobs, Tom P
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of California San Francisco
Schools of Medicine
San Francisco
United States
Zip Code
Haraldsson, Henrik; Hope, Michael; Acevedo-Bolton, Gabriel et al. (2014) Feasibility of asymmetric stretch assessment in the ascending aortic wall with DENSE cardiovascular magnetic resonance. J Cardiovasc Magn Reson 16:6
Liu, Jing; Dyverfeldt, Petter; Acevedo-Bolton, Gabriel et al. (2014) Highly accelerated aortic 4D flow MR imaging with variable-density random undersampling. Magn Reson Imaging 32:1012-20
Dyverfeldt, Petter; Deshpande, Vibhas S; Kober, Tobias et al. (2014) Reduction of motion artifacts in carotid MRI using free-induction decay navigators. J Magn Reson Imaging 40:214-20
Burris, Nicholas S; Sigovan, Monica; Knauer, Heather A et al. (2014) Systolic flow displacement correlates with future ascending aortic growth in patients with bicuspid aortic valves undergoing magnetic resonance surveillance. Invest Radiol 49:635-9
Hope, Michael D; Sigovan, Monica; Wrenn, S Jarrett et al. (2014) MRI hemodynamic markers of progressive bicuspid aortic valve-related aortic disease. J Magn Reson Imaging 40:140-5
Dyverfeldt, Petter; Hope, Michael D; Tseng, Elaine E et al. (2013) Magnetic resonance measurement of turbulent kinetic energy for the estimation of irreversible pressure loss in aortic stenosis. JACC Cardiovasc Imaging 6:64-71
Hasan, David M; Mahaney, Kelly B; Magnotta, Vincent A et al. (2012) Macrophage imaging within human cerebral aneurysms wall using ferumoxytol-enhanced MRI: a pilot study. Arterioscler Thromb Vasc Biol 32:1032-8
Boussel, Loic; Rayz, Vitaliy; Martin, Alastair et al. (2011) Temporal stability of dysmorphic fusiform aneurysms of the intracranial internal carotid artery. J Vasc Interv Radiol 22:1007-11
Martin, A J; Hetts, S W; Dillon, W P et al. (2011) MR imaging of partially thrombosed cerebral aneurysms: characteristics and evolution. AJNR Am J Neuroradiol 32:346-51
Rayz, V L; Boussel, L; Ge, L et al. (2010) Flow residence time and regions of intraluminal thrombus deposition in intracranial aneurysms. Ann Biomed Eng 38:3058-69

Showing the most recent 10 out of 13 publications