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.

Determining the Presence of Thin-Walled Regions at High-Pressure Areas in Unruptured Cerebral Aneurysms by Using Computational Fluid Dynamics

Neurosurgery ◽  
2016 ◽  
Vol 79 (4) ◽  
pp. 589-595 ◽  
Author(s):  
Tomoaki Suzuki ◽  
Hiroyuki Takao ◽  
Takashi Suzuki ◽  
Yukinao Kambayashi ◽  
Mitsuyoshi Watanabe ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Pressure ◽  
Dynamic Pressure ◽  
Cerebral Aneurysms ◽  
Maximum Pressure ◽  
Pressure Elevation ◽  
Risk Of Rupture ◽  
Thin Walled ◽  
Unruptured Cerebral Aneurysms

Abstract BACKGROUND Thin-walled regions (TWRs) of cerebral aneurysms are at high risk of rupture, and careful attention should be paid during surgical procedures. Despite this, an optimal imaging technique to estimate TWRs has not been established. Previously, pressure elevation at TWRs was reported with computational fluid dynamics (CFD) but not fully evaluated. OBJECTIVE To investigate the possibility of predicting aneurysmal TWRs at high-pressure areas with CFD. METHODS Fifty unruptured middle cerebral artery aneurysms were analyzed. Spatial and temporal maximum pressure (Pmax) areas were determined with a fluid-flow formula under pulsatile blood flow conditions. Intraoperatively, TWRs of aneurysm domes were identified as reddish areas relative to the healthy normal middle cerebral arteries; 5 neurosurgeons evaluated and divided these regions according to Pmax area and TWR correspondence. Pressure difference (PD) was defined as the degree of pressure elevation on the aneurysmal wall at Pmax and was calculated by subtracting the average pressure from the Pmax and dividing by the dynamic pressure at the aneurysm inlet side for normalization. RESULTS In 41 of the 50 cases (82.0%), the Pmax areas and TWRs corresponded. PD values were significantly higher in the correspondence group than in the noncorrespondence group (P = .008). A receiver-operating characteristic curve demonstrated that PD accurately predicted TWRs at Pmax areas (area under the curve, 0.764; 95% confidence interval, 0.574-0.955; cutoff value, 0.607; sensitivity, 66.7%; specificity, 82.9%). CONCLUSION A high PD may be a key parameter for predicting TWRs in unruptured cerebral aneurysms.

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.

Colocalization of thin-walled dome regions with low hemodynamic wall shear stress in unruptured cerebral aneurysms

2013 ◽  
Vol 119 (1) ◽  
pp. 172-179 ◽  
Author(s):  
Laith M. Kadasi ◽  
Walter C. Dent ◽  
Adel M. Malek
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
Wall Shear Stress ◽  
Cerebral Aneurysms ◽  
Pressure Differential ◽  
Time Dependent ◽  
Aneurysm Wall ◽  
Thin Walled ◽  
Wall Shear ◽  
Unruptured Cerebral Aneurysms

Object Wall shear stress (WSS) plays a role in regulating endothelial function and has been suspected in cerebral aneurysm rupture. The aim of this study was to evaluate the spatial relationship between localized thinning of the aneurysm dome and estimated hemodynamic factors, hypothesizing that a low WSS would correlate with aneurysm wall degeneration. Methods Steady-state computational fluid dynamics analysis was performed on 16 aneurysms in 14 patients based on rotational angiographic volumes to derive maps of WSS, its spatial gradient (WSSG), and pressure. Local dome thickness was estimated categorically based on tissue translucency from high-resolution intraoperative microscopy findings. Each computational model was oriented to match the corresponding intraoperative view and numerically sampled in thin and normal adjacent dome regions, with controls at the neck and parent vessel. The pressure differential was computed as the difference between aneurysm dome points and the mean neck pressure. Pulsatile time-dependent confirmatory analysis was carried out in 7 patients. Results Matched-pair analysis revealed significantly lower levels of WSS (0.381 Pa vs 0.816 Pa; p < 0.0001) in thin-walled dome areas than in adjacent baseline thickness regions. Similarly, log WSSG and log WSS × WSSG were both lower in thin regions (both p < 0.0001); multivariate logistic regression analysis identified lower WSS and higher pressure differential as independent correlates of lower wall thickness with an area under the curve of 0.80. This relationship was observed in both steady-state and time-dependent pulsatile analyses. Conclusions Thin-walled regions of unruptured cerebral aneurysms colocalize with low WSS, suggesting a cellular mechanotransduction link between areas of flow stasis and aneurysm wall thinning.

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.

scholarly journals Non-Atherosclerotic Fusiform Cerebral Aneurysms

2002 ◽  
Vol 29 (1) ◽  
pp. 41-48 ◽  
Author(s):  
J. Max Findlay ◽  
Chunhai Hao ◽  
Derek Emery
Keyword(s):  
Connective Tissue ◽  
Cerebral Aneurysms ◽  
Side Wall ◽  
Endovascular Coiling ◽  
Parent Artery ◽  
Cerebral Atherosclerosis ◽  
Parent Artery Occlusion ◽  
Risk Of Rupture ◽  
Thin Walled ◽  
Proximal Occlusion

Background:Fusiform cerebral aneurysms are dilatations of the entire circumference of a segment of cerebral artery, usually considered due to atherosclerosis in adults. They are relatively thick-walled and elongated, causing neural compression or ischemia when discovered. We have noted a subset of fusiform cerebral aneurysms that vary from this common description.Patients:Out of a series of 472 intracranial aneurysms treated over 11 years, 11 patients between the ages 16 and 67 years (mean age 37) were identified who had discrete fusiform aneurysms unassociated with generalized cerebral atherosclerosis, connective tissue disorder or inflammation. Three presented with hemorrhage, six with neural compression by the aneurysm and two were discovered incidentally.Results:Nine aneurysms were located in the posterior circulation, the other two in the intracranial carotid artery. Their mean length and width were 16.3 and 11 mm, respectively. Three aneurysms contained thrombus. The eight aneurysms that were exposed surgically were partly or substantially thin-walled with normal appearing parent arteries. Eight were treated with proximal occlusion and three were circumferentially “wrapped”. Parent artery occlusion caused one death and one mild disability and the remaining patients made good recoveries (follow-up 0.5 - 10 years).Conclusions:There is a subset of cerebral aneurysms with discrete fusiform morphology, apparently unrelated to cerebral atherosclerosis or systemic connective tissue disease, thin-walled in part or whole, more common in the vertebrobasilar system, and possessing a risk of rupture. Treatments currently available include proximal occlusion or aneurysm “wrapping”, different approaches than neck-clipping or endovascular coiling of side-wall saccular cerebral aneurysms that leave the parent artery intact.

Abstract 2731: CFD Reveals Hemodynamic Differences Between Unruptured And Ruptured Intracranial Aneurysms During Observation

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Hiroyuki Takao ◽  
Yuichi Murayama ◽  
Toshihiro Ishibashi ◽  
Ichiro Yuki ◽  
Shinobu Otsuka ◽  
...  
Keyword(s):  
Cerebral Aneurysm ◽  
Significant Risk ◽  
Cerebral Aneurysms ◽  
Aneurysm Rupture ◽  
Medium Size ◽  
Hemodynamic Parameters ◽  
Natural Risk ◽  
Risk Of Rupture ◽  
Significant Difference

Background and Purpose: Although various studies have been performed, the mechanism leading to the rupture of cerebral aneurysms has not yet been elucidated. Accurate assessment of cerebral aneurysm rupture risk is important because current treatments carry a small but significant risk that can exceed the small natural risk of rupture. Various hemodynamic parameters have been proposed for estimating the risk of rupture of cerebral aneurysms, with limited success. We evaluated several hemodynamic parameters to predict rupture in a dataset of initially unruptured aneurysms in which some aneurysms ruptured during follow-up observation. Methods: Geometry of the aneurysm and blood vessels was extracted from CTA images and analyzed using a mathematical formula for fluid flow under pulsatile blood flow conditions. Fifty side-wall internal carotid posterior communicating artery (ICA-pcom) aneurysms and fifty middle cerebral artery (MCA) bifurcation aneurysms of medium size were investigated for Energy loss (EL), Pressure Loss Coefficient (PLC), wall-shear-stress (WSS) and oscillatory shear index (OSI). During a follow-up observation period, 6 ICA-pcom and 7 MCA aneurysms ruptured (44 and 43 remained unruptured, respectively, with the same location and a similar size as the ruptured cases). Results: A significant difference in the minimum WSS between aneurysms that ruptured and those that remained unruptured was noted only in ICA aneurysms (P<0.001). EL showed higher tendency in ruptured aneurysms but statistically not significant. For PLC, a significant difference was noted in both ICA (P<0.001) and MCA (P<0.001) aneurysms. All other parameters did not show significant differences between the two groups. Conclusion: A significant difference was noted in WSSMIN only in ICA aneurysms. For PLC, a significant difference was noted in both ICA and MCA aneurysms, suggesting that PLC may be one, out of possibly other useful parameters to predict cerebral aneurysm rupture.

High-Fidelity Finite Element Mesh Generation for Fluid-Structure Interaction Analysis of Cerebral Aneurysms

2009 ◽  
Author(s):  
Yongjie Zhang ◽  
Wenyan Wang ◽  
Xinghua Liang ◽  
Yuri Bazilevs ◽  
Ming-Chen Hsu ◽  
...  
Keyword(s):  
Mesh Generation ◽  
Interaction Analysis ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Material Strength ◽  
Element Mesh ◽  
Computational Tools ◽  
Unruptured Cerebral Aneurysms ◽  
Ideal Method ◽  
Invasive Measurement

Nowadays approximately 3–6% of the population is estimated to have unruptured cerebral aneurysms. The rupture risk of aneurysms can be predicted by using computational tools and patient-specific models. As an ideal method, we can assess the risk factors by determining the blood tension and the material strength of the wall tissue in the aneurisms. Although it is hard to obtain aneurismal material strength without invasive measurement, it is possible to estimate the wall tension by numerical simulation [1].

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 Clear Detection of Thin-Walled Regions in Unruptured Cerebral Aneurysms by Using Computational Fluid Dynamics

2019 ◽  
Vol 121 ◽  
pp. e287-e295 ◽  
Author(s):  
Hidehito Kimura ◽  
Masaaki Taniguchi ◽  
Kosuke Hayashi ◽  
Yosuke Fujimoto ◽  
Youichi Fujita ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cerebral Aneurysms ◽  
Thin Walled ◽  
Unruptured Cerebral Aneurysms
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