I am an Associate Professor in the Computational and Data Sciences Department of the College of Sciences at GMU and the Center for Computational Fluid Dynamics. Recently, I have been invited by Jim to join Krasnow and to write a summary of our research. Here it is…
Stroke is the third cause of death after heart disease and cancer, and the leading cause of long term disability. Strokes can be ischemic (due to a diminution of blood supply to the brain) or hemorrhagic (bleeding into the brain). Ischemic strokes are most commonly caused by the blockage of a feeding vessel due to athersclerotic narrowing of the vessels or due to emboli. The major source of ischemic stroke is carotid artery atherosclerosis. Hemorrhagic strokes are most commonly due to the rupture of a cerebral aneurysm. Cerebral aneurysms are pathological dilatations of the arterial wall, typically located at or near arterial bifurcations in the circle of Willis. The vascular architecture of the brain is unique in the human body because the circle of Willis provides a redundant network of vessels, reflecting the important nature of a constant oxygen supply to the brain.
Our current research focuses on intracranial aneurysms. With advances in modern medical imaging techniques, unruptured aneurysms are more frequently detected. Because the prognosis of cerebral hemorrhage is still very poor, preventive treatment is frequently performed. However, the risks associated with surgical and endovascular interventions may exceed the rupture risk of the aneurysm if left untreated. Therefore, the best option would be to treat only those patients at higher risk. This requires a better understanding of the mechanisms responsible for aneurysm initiation, growth and rupture. Previous studies have identified the major factors involved in these processes: a) arterial hemodynamics (blood flows), b) arterial mechanobiology, and c) the peri-aneurysmal environment.
Our research goals are to better understand the mechanisms of aneurysm development, progression and rupture, to develop computational tools for assessing the rupture risk of individual patients, and to optimize and peronalize minimally invasive endovascular procedures to treat these patients. To this end, we are constructing patient-specific computational fluid dynamics models of brain aneurysms from 3D rotational angiography images in order to quantify the in vivo blood flow patterns and hemodynamic forces on the aneurysm walls. Using this methodology, we are developing a database of cerebral aneurysms that contains, clinical information, medical images and computational models of blood flow patterns. We are using all this information to study possible relationships between anatomical and hemodynamic characteristics and clinical events such as aneurysm rupture or the development of symptoms. In parallel, we are developing techniques to simulate blood flows after deployment of endovascular devices such as coils and stents used to treat these aneurysms. This is a challenging problem because of the complex geometry of the vessel and the devices. However, we are using a so called mesh embedding approach that greatly simplifies this problem and allows us to perform “virtual” interventions in order to predict what the effects of a given device would be for a particular patient. This would allow us to select the best treatment option for an individual. This is quite important for aneurysms that are difficult to treat with coils or by surgical clipping. In addition, we are constructing models of the circle of Willis from magnetic resonance angiography images of normal subjects in order to characterize the vascular architecture of the brain and the hemodynamic patterns in the main arteries feeding the brain. This information is important for prescribing “typical” physiologic flow conditions in the simulations when they are not available for an given patient. It is also important for understanding the role of hemodynamics in the process of aneurysm initiation, and the role of the collateral pathways provided by the circle of Willis during arterial occlusions and medical interventions. Our research is highly multidisciplinary, it involves medical image analysis, computational geometry, computational fluid dynamics, high performance computing, computer graphics and visualization, biomechanics, cell mechanotransduction, and clinical research. For this reason we are collaborating with a number of colleagues in the US and around the world. In particular, we maintain a strong collaboration with the Neuroradiology division of Inova Fairfax Hospital, the Interventional Neuroradiology unit at UCLA (the largest site for cerebral aneurysms) and with the Computational Imaging Lab of the Pompeu Fabra University in Barcelona, Spain. Support for this research has come from the Whitaker Foundation, Philips Medical Systems and the American Heart Association. We look forward to continuing our research in this exciting area and to make an impact on the way medicine is practiced today. Transforming medicine into a predictive science has the potential of tremendously improving patient evaluation and management, which is our ultimately objective. JRC
Discoverers and Discoveries 