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IPA Lab | Image Processing Applications Laboratory

Cerebral Aneurysm


Cerebral aneurysms (CA) or intracranial aneurysms are localized dilations of blood vessels in the brain that affect 1 in 50 people [1]. Cerebral aneurysm rupture leads to a critical medical condition known as Subarachnoid Hemorrhage (SAH) that is often fatal or may lead to permanent neurological deficits.

The treatment goal is to eliminate flow into the aneurysm, thereby facilitating long term processes that seals off the aneurysm from normal circulation. Over the last decade, endovascular treatment of CAs has gained popularity. Common treatments include aneurysm occlusion with embolic coils, and flow diversion with stents. Despite the advantages of endovascular treatments over conventional surgical techniques, they are often unsuccessful.


The objective of current studies is to establish a foundation for understanding the fluid dynamics of aneurysms treated with endovascular devices through in-vitro experimentation and in-silico simulations. We are also investigating the effects of various novel endovascular devices oncerebral aneurysm fluid dynamics. The ultimate goal of these studies is to improve treatment outcomes for patients with cerebral aneurysms.

Current Status:

Effects of Basilar Tip Aneurysm Geometry on Endovascular Treatment Outcomes

Aneurysm geometry is extensively characterized in the clinic and is the primary factor considered during CA evaluation and treatment planning. On the other hand, although hemodynamics is known play an important role in CA progression and growth it is considered to a limited degree in CA evaluation. This study quantifies the effect of CA geometry on hemodynamics using in-silico simulations and in-vitro experimentations before and after treatment with endovascular devices. Eight unique idealized basilar tip (BTA) aneurysms are chosen in this study using a factorial design as shown in Figure 1 where the vertices correspond to a combination of dome size, dome to neck ratio and parent-vessel contact angle. Embolic coils, pipeline flow diverter and a high porosity stent was used as the treatment option depending on the type of aneurysm geometry. Figure 2 represents vector plots comparing in-slilico and in-vitro results. This project was funded by the American Heart Association

Figure 1: 2-level factorial design with three factors (dome size, dome-to-neck ratio and parent vessel contact angle).


Figure 2: In-silico (left) and in-vitro (right) results in an idealized basilar tip aneurysm.

Top: Untreated model, Middle: Low coil packing density, Bottom: High coil packing density

Treatment with Embolic Coils

Coil packing rate and aneurysmal geometric features:

In an in-vitro study using particle-image velocimetry (PIV), we have quantified a relationship between coil packing density and clinically relevant aneurysm fluid dynamic parameters in parametric idealized aneurysm models. This quantitative information relates specific aneurysmal geometric features to post-treatment aneurysm fluid dynamics [3].

Coil Design:

We have also evaluated the performance of conventional and new embolic coil designs on post-treatment aneurysm fluid dynamics in separate studies

PIV velocity magnitude vectors acquired from a narrow-neck basilar tip aneurysm model at different packing densities

Treatment with Endovascular Stents

Stent configurations in bifurcating aneurysms:

Using both PIV and computational fluid dynamics (CFD) we have quantified the performance of different stent configurations on aneurysmal fluid dynamics

CFD simulations for two stent configurations

PIV velocity magnitude vectors for three stent configurationsTelescoping stents

A common treatment for wide-neck cerebral aneurysms is multiple stent-in-stent deployments that reduce stent porosity and enhance flow diversion. We have conducted in-vitro studies to quantify the changes in aneurysmal fluid dynamics using these techniques.

Stand-alone Stent treatment

In collaboration with the Center for Advanced Surgical and Interventional Technolgy at UCLA, we are investigating the fluid dynamic performance of a Hyper-Elastic Thin Film Nitinol (HE-TFN) covered stent for stand-alone stent treatment.

Velocity magnitude vectors within a  sidewall aneurysm treated with two different HE-TFN covered struts

1] Rinkel, G., M. Djibuti, A. Algra, and J. V. Gijn. Prevalence and risk of rupture of intracranial aneurysms: a systematic review. Stroke 29:251–256, 1998.

[2] Schievink, W. Intracranial aneurysms. N. Engl. J. Med. 336:28–40, 1997.

[3] Babiker MH, Gonzalez LF, Albuquerque F, Collins D, Elvikis A, Frakes DH (2010) Quantitative effects of coil packing density on cerebral aneurysm fluid dynamics: An in vitro steady flow study. Ann Biomed Eng 38:2293–2301