Geometry Anticipates Hemodynamic Phenotype of Basilar Tip Aneurysms

2007 ◽  
Author(s):  
Matthew D. Ford ◽  
Sang-Wook Lee ◽  
Stephen P. Lownie ◽  
David W. Holdsworth ◽  
David A. Steinman
Keyword(s):  
Endovascular Therapy ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Clinical Use ◽  
Hemodynamic Forces ◽  
Risk Of Rupture ◽  
Specific Manner ◽  
Computational Fluid Dynamics Cfd ◽  
Unruptured Cerebral Aneurysms ◽  
Hemodynamic Information

The prevalence of unruptured cerebral aneurysms is estimated to be as high as 5% [1]. Basilar tip aneurysms account for 4–5% of these, but have a higher risk of rupture [2]. They are also difficult to treat surgically, and so endovascular therapy is often the only option. Hemodynamic forces have been implicated in the risk of rupture [3] and complications of endovascular therapy [4]; however, hemodynamic information is difficult to acquire clinically. Computational fluid dynamics (CFD), in combination with clinical imaging, can be used to accurately capture the intra-aneurysmal hemodynamics in a patient-specific manner [5]. Still, these techniques have not translated to routine clinical use, largely due to the time and effort required to construct, simulate, and interpret these models.

scholarly journals A Workflow for Patient-Individualized Virtual Angiogram Generation Based on CFD Simulation

2012 ◽  
Vol 2012 ◽  
pp. 1-24 ◽  
Author(s):  
Jürgen Endres ◽  
Markus Kowarschik ◽  
Thomas Redel ◽  
Puneet Sharma ◽  
Viorel Mihalef ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Cfd Simulation ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Hemodynamic Parameters ◽  
Risk Of Rupture ◽  
Computational Fluid Dynamics Cfd ◽  
Subsequent Comparison

Increasing interest is drawn on hemodynamic parameters for classifying the risk of rupture as well as treatment planning of cerebral aneurysms. A proposed method to obtain quantities such as wall shear stress, pressure, and blood flow velocity is to numerically simulate the blood flow using computational fluid dynamics (CFD) methods. For the validation of those calculated quantities, virtually generated angiograms, based on the CFD results, are increasingly used for a subsequent comparison with real, acquired angiograms. For the generation of virtual angiograms, several patient-specific parameters have to be incorporated to obtain virtual angiograms which match the acquired angiograms as best as possible. For this purpose, a workflow is presented and demonstrated involving multiple phantom and patient cases.

scholarly journals Morphological and Hemodynamic Changes during Cerebral Aneurysm Growth

2021 ◽  
Vol 11 (4) ◽  
pp. 520
Author(s):  
Emily R. Nordahl ◽  
Susheil Uthamaraj ◽  
Kendall D. Dennis ◽  
Alena Sejkorová ◽  
Aleš Hejčl ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Swirling Flow ◽  
Morphological Changes ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Aneurysm Wall ◽  
Aneurysm Growth ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) has grown as a tool to help understand the hemodynamic properties related to the rupture of cerebral aneurysms. Few of these studies deal specifically with aneurysm growth and most only use a single time instance within the aneurysm growth history. The present retrospective study investigated four patient-specific aneurysms, once at initial diagnosis and then at follow-up, to analyze hemodynamic and morphological changes. Aneurysm geometries were segmented via the medical image processing software Mimics. The geometries were meshed and a computational fluid dynamics (CFD) analysis was performed using ANSYS. Results showed that major geometry bulk growth occurred in areas of low wall shear stress (WSS). Wall shape remodeling near neck impingement regions occurred in areas with large gradients of WSS and oscillatory shear index. This study found that growth occurred in areas where low WSS was accompanied by high velocity gradients between the aneurysm wall and large swirling flow structures. A new finding was that all cases showed an increase in kinetic energy from the first time point to the second, and this change in kinetic energy seems correlated to the change in aneurysm volume.

Abstract 1122‐000145: Impact of Age on Outcomes Following Endovascular vs Clipping of Ruptured and Unruptured Cerebral Aneurysms

2021 ◽  
Vol 1 (S1) ◽  
Author(s):  
Hamidreza Saber ◽  
Naoki Kaneko ◽  
David Kimball ◽  
Jose Morales ◽  
Satoshi Tateshima ◽  
...  
Keyword(s):  
Hospital Mortality ◽  
Endovascular Therapy ◽  
Age Groups ◽  
Cerebral Aneurysms ◽  
Unruptured Aneurysm ◽  
Favorable Outcome ◽  
Hospital Length Of Stay ◽  
Surgical Clipping ◽  
Unruptured Aneurysms ◽  
Unruptured Cerebral Aneurysms

Introduction : Age is an important determinant of outcome in patients with unruptured or ruptured cerebral aneurysms. Advancements in endovascular therapies have significantly impacted patient selection and treatment of patients with cerebral aneurysm. Recent release of the National claims data for 2017–2018 provides the opportunity to explore novel population‐level outcomes following clipping vs endovascular treatment of ruptured and unruptured cerebral aneurysms in different age groups. Methods : Analysis of US National Inpatient Sample of hospitalizations with aneurysmal subarachnoid hemorrhage (aSAH) or unruptured aneurysms treated with clipping or endovascular therapy from January 1, 2017 to December 31, 2018. Pre‐defined age strata included: younger than 50 years; 50–64 years; 65–79 years; and 80 years or older. Primary outcomes included in‐hospital mortality and favorable outcome defined as discharge to home. Results : Overall, 34,955 hospitalizations with unruptured aneurysm treatment, (26,695 endovascular and 8,260 surgical clipping), and 17,525 hospitalizations with aSAH were identified in the study period. In unruptured aneurysm group, endovascular therapy was associated with significantly higher favorable outcome across all age groups, and lower mortality in those 65 years or older (all P<0.001) when compared to clipping. Median hospital length‐of‐stay was 1 day (IQR 1–4) in endovascular vs 4 days (IQR 3–8) in clipping group (P<0.001). In aSAH group, endovascular therapy was associated with higher favorable outcome in 50–80 years age groups when compared to clipping, with no significant differences for in‐hospital mortality outcome (Table). Significantly more favorable outcomes were achieved with coiling vs clipping in those aged 65 or above with unruptured aneurysms. Conclusions : In 2017–2018 in US, unruptured aneurysm patients treated with endovascular therapy had significantly lower morbidity and mortality compared to those treated with surgical clipping, and differences were more pronounced with age. Similar but less strong association was observed in patients with aSAH.

scholarly journals Prediction of Thin-Walled Areas of Unruptured Cerebral Aneurysms through Comparison of Normalized Hemodynamic Parameters and Intraoperative Images

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Kwang-Chun Cho ◽  
Ji Hun Choi ◽  
Je Hoon Oh ◽  
Yong Bae Kim
Keyword(s):  
Interaction Analysis ◽  
Cerebral Aneurysms ◽  
Weighted Average ◽  
Weighting Factor ◽  
Hemodynamic Parameters ◽  
Color Analysis ◽  
Risk Of Rupture ◽  
Thin Walled ◽  
Unruptured Cerebral Aneurysms ◽  
Normalization Scheme

Object. Rupture of a cerebral aneurysm occurs mainly in a thin-walled area (TWA). Prediction of TWAs would help to assess the risk of rupture and select appropriate treatment strategy. There are several limitations of current prediction techniques for TWAs. To predict TWAs more accurately, HP should be normalized to minimize the influence of analysis conditions, and the effectiveness of normalized, combined hemodynamic parameters (CHPs) should be investigated with help of the quantitative color analysis of intraoperative images. Methods. A total of 21 unruptured cerebral aneurysms in 19 patients were analyzed. A normalized CHP was newly suggested as a weighted average of normalized wall shear stress (WSS) and normalized oscillatory shear index (OSI). Delta E from International Commission on Illumination was used to more objectively quantify color differences in intraoperative images. Results. CFD analysis results indicated that WSS and OSI were more predictive of TWAs than pressure (P<.001, P=.187, P=.970, respectively); these two parameters were selected to define the normalized CHP. The normalized CHP became more statistically significant (P<.001) as the weighting factor of normalized WSS increased and that of normalized OSI decreased. Locations with high CHP values corresponded well to those with high Delta E values (P<.001). Predicted TWAs based on the normalized CHP showed a relatively good agreement with intraoperative images (17 in 21 cases, 81.0%). Conclusion. 100% weighting on the normalized WSS produced the most statistically significant result. The normalization scheme for WSS and OSI suggested in this work was validated using quantitative color analyses, rather than subjective judgments, of intraoperative images, and it might be clinically useful for predicting TWAs of unruptured cerebral aneurysms. The normalization scheme would also be integrated into further fluid-structure interaction analysis for more reliable estimation of the risk of aneurysm rupture.

scholarly journals Risk of unruptured aneurysm treatment in California

Stroke ◽  
2001 ◽  
Vol 32 (suppl_1) ◽  
pp. 381-381
Author(s):  
S. Claiborne Johnston ◽  
Shoujun Zhao ◽  
R. Adams Dudley ◽  
Daryl R Gress
Keyword(s):  
Adverse Events ◽  
Cerebral Aneurysm ◽  
Endovascular Therapy ◽  
Odds Ratio ◽  
Cerebral Aneurysms ◽  
Hospital Treatment ◽  
Hospital Death ◽  
Hospital Deaths ◽  
The Difference ◽  
Unruptured Cerebral Aneurysms

P230 Background. Few studies have directly compared the risk of cerebral aneurysm repair with surgery and with endovascular coil embolization. Since the vast majority of patients with unruptured cerebral aneurysms are non-disabled prior to treatment, this diagnosis provides an opportunity to compare risks of treatment. Methods. Discharge abstracts for all patients with a primary diagnosis of unruptured cerebral aneurysm were retrieved from a statewide database of non-Federal hospital discharges in California from January 1990 through December 1998. Admissions for initial treatment and all follow-up care were combined to reflect the entire course of therapy. An adverse event was defined as an in-hospital death or discharge to nursing home or rehabilitation hospital at any point during the treatment course. Results. A total of 2069 patients were treated for unruptured aneurysms. Adverse outcomes were more frequent in the 1699 patients treated with surgery than in the 370 treated with endovascular therapy (25% vs. 10%; p<0.0001 by chi-square test). The difference persisted after adjustment for age, gender, race, source of admission, and year of treatment (odds ratio 3.5 for adverse events surgery vs. endovascular therapy, 95% confidence interval 2.4–5.2, p<0.0001 by logistic regression). In-hospital deaths occurred in 3.5% of surgical cases and 0.5% of endovascular cases (p=0.003), and the difference remained significant after adjustment in multivariable models (odds ratio 6.3, 1.5–26.2, p=0.01). Adverse events were less likely at hospitals treating a larger portion of patients with endovascular therapy after adjustment for case characteristics, hospital treatment volume, and clustering of observations using generalized estimating equations (p=0.006). Conclusions. In California, endovascular repair of unruptured cerebral aneurysms is associated with fewer adverse events and in-hospital deaths than surgery.

scholarly journals Size-Dependent Distribution of Patient-Specific Hemodynamic Factors in Unruptured Cerebral Aneurysms Using Computational Fluid Dynamics

Diagnostics ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 64 ◽  
Author(s):  
Ui Yun Lee ◽  
Gyung Ho Chung ◽  
Jinmu Jung ◽  
Hyo Sung Kwak
Keyword(s):  
Fluid Dynamics ◽  
Shear Rate ◽  
Blood Viscosity ◽  
Cerebral Aneurysms ◽  
Velocity Shear ◽  
Patient Specific ◽  
Complex Flow ◽  
Size Dependent ◽  
Unruptured Cerebral Aneurysms ◽  
Small Aneurysms

Purpose: To analyze size-dependent hemodynamic factors [velocity, shear rate, blood viscosity, wall shear stress (WSS)] in unruptured cerebral aneurysms using computational fluid dynamics (CFD) based on the measured non-Newtonian model of viscosity. Methods: Twenty-one patients with unruptured aneurysms formed the study cohort. Patient-specific geometric models were reconstructed for CFD analyses. Aneurysms were divided into small and large groups based on a cutoff size of 5 mm. For comparison between small and large aneurysms, 5 morphologic variables were measured. Patient-specific non-Newtonian blood viscosity was applied for more detailed CFD simulation. Quantitative and qualitative analyses of velocity, shear rate, blood viscosity, and WSS were conducted to compare small and large aneurysms. Results: Complex flow patterns were found in large aneurysms. Large aneurysms had a significantly lower shear rate (235 ± 341 s−1) than small aneurysms (915 ± 432 s−1) at peak-systole. Two times higher blood viscosity was observed in large aneurysms compared with small aneurysms. Lower WSS was found in large aneurysms (1.38 ± 1.36 Pa) than in small aneurysms (3.53 ± 1.22 Pa). All the differences in hemodynamic factors between small and large aneurysms were statistically significant. Conclusions: Large aneurysms tended to have complex flow patterns, low shear rate, high blood viscosity, and low WSS. The hemodynamic factors that we analyzed might be useful for decision making before surgical treatment of aneurysms.

scholarly journals Computational Fluid Dynamics for Cerebral Aneurysms in Clinical Settings

2021 ◽  
pp. 27-32
Author(s):  
Fujimaro Ishida ◽  
Masanori Tsuji ◽  
Satoru Tanioka ◽  
Katsuhiro Tanaka ◽  
Shinichi Yoshimura ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Clinical Settings ◽  
Geometry Model ◽  
Aneurysm Wall ◽  
3D Ct Angiography ◽  
Specific Geometry ◽  
Computational Fluid Dynamics Cfd

AbstractHemodynamics is thought to play an important role in the pathogenesis of cerebral aneurysms and recent development of computer technology makes it possible to simulate blood flow using high-resolution 3D images within several hours. A lot of studies of computational fluid dynamics (CFD) for cerebral aneurysms were reported; therefore, application of CFD for cerebral aneurysms in clinical settings is reviewed in this article.CFD for cerebral aneurysms using a patient-specific geometry model was first reported in 2003 and it has been revealing that hemodynamics brings a certain contribution to understanding aneurysm pathology, including initiation, growth and rupture. Based on the knowledge of the state-of-the-art techniques, this review treats the decision-making process for using CFD in several clinical settings. We introduce our CFD procedure using digital imaging and communication in medicine (DICOM) datasets of 3D CT angiography or 3D rotational angiography. In addition, we review rupture status, hyperplastic remodeling of aneurysm wall, and recurrence of coiled aneurysms using the hemodynamic parameters such as wall shear stress (WSS), oscillatory shear index (OSI), aneurysmal inflow rate coefficient (AIRC), and residual flow volume (RFV).

scholarly journals Vortex Analysis of Intra-Aneurismal Flow in Cerebral Aneurysms

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Kevin Sunderland ◽  
Christopher Haferman ◽  
Gouthami Chintalapani ◽  
Jingfeng Jiang
Keyword(s):  
Vortex Core ◽  
Cardiac Cycle ◽  
Temporal Stability ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Cfd Simulations ◽  
Hemodynamic Characteristics ◽  
Computational Fluid Dynamics Cfd ◽  
Marching Cube Algorithm ◽  
Core Characteristics

This study aims to develop an alternative vortex analysis method by measuring structure ofIntracranial aneurysm (IA) flow vortexes across the cardiac cycle, to quantify temporal stability of aneurismal flow. Hemodynamics were modeled in “patient-specific” geometries, using computational fluid dynamics (CFD) simulations. Modified versions of knownλ2andQ-criterion methods identified vortex regions; then regions were segmented out using the classical marching cube algorithm. Temporal stability was measured by the degree of vortex overlap (DVO) at each step of a cardiac cycle against a cycle-averaged vortex and by the change in number of cores over the cycle. No statistical differences exist in DVO or number of vortex cores between 5 terminal IAs and 5 sidewall IAs. No strong correlation exists between vortex core characteristics and geometric or hemodynamic characteristics of IAs. Statistical independence suggests this proposed method may provide novel IA information. However, threshold values used to determine the vortex core regions and resolution of velocity data influenced analysis outcomes and have to be addressed in future studies. In conclusions, preliminary results show that the proposed methodology may help give novel insight toward aneurismal flow characteristic and help in future risk assessment given more developments.

scholarly journals Propose a Wall Shear Stress Divergence to Estimate the Risks of Intracranial Aneurysm Rupture

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Y. Zhang ◽  
H. Takao ◽  
Y. Murayama ◽  
Y. Qian
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Intracranial Aneurysm ◽  
Risk Estimation ◽  
Aneurysm Rupture ◽  
Patient Specific ◽  
Luminal Surface ◽  
Risk Of Rupture ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Shear

Although wall shear stress (WSS) has long been considered a critical indicator of intracranial aneurysm rupture, there is still no definite conclusion as to whether a high or a low WSS results in aneurysm rupture. The reason may be that the effect of WSS direction has not been fully considered. The objectives of this study are to investigate the magnitude of WSS (WSS) and its divergence on the aneurysm surface and to test the significance of both in relation to the aneurysm rupture. Patient-specific computational fluid dynamics (CFD) was used to compute WSS and wall shear stress divergence (WSSD) on the aneurysm surface for nineteen patients. Our results revealed that if highWSSis stretching aneurysm luminal surface, and the stretching region is concentrated, the aneurysm is under a high risk of rupture. It seems that, by considering both direction and magnitude of WSS, WSSD may be a better indicator for the risk estimation of aneurysm rupture (154).

Natural history and general management of unruptured intracranial aneurysms

2004 ◽  
Vol 17 (5) ◽  
pp. 1-6 ◽  
Author(s):  
Peng Roc Chen ◽  
Kai Frerichs ◽  
Robert Spetzler
Keyword(s):  
Natural History ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Cerebral Aneurysms ◽  
Population Based ◽  
Unruptured Aneurysms ◽  
Unruptured Intracranial Aneurysms ◽  
Risk Of Rupture ◽  
History Of ◽  
Unruptured Cerebral Aneurysms ◽  
Noninvasive Neuroimaging

After an aneurysmal subarachnoid hemorrhage, nearly half of the patients die and the half who survive suffer from irreversible cerebral damage. With increasing use of noninvasive neuroimaging techniques (for example, magnetic resonance and computerized tomography angiography), more unruptured cerebral aneurysms are found. To understand the prevalence of unruptured aneurysms in the general population, along with the risks of aneurysm formation, data on growth and rupture rates are crucial. The risk of rupture in aneurysms smaller than 10 mm is still not quite clear without a population-based prospective study. Nevertheless, a 0.5 to 2% annual risk may be a reasonable estimate. Growing aneurysms and those larger than 10 mm carry a higher rate of rupture. The management of an unruptured intracranial aneurysm should be based on a thorough understanding of the natural history of these lesions and careful evaluation of the morbidity and mortality levels associated with each treatment option.

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