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

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.

Download Full-text

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

Neurosurgery ◽

10.1097/00006123-201610000-00029 ◽

2016 ◽

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

High Pressure ◽

Cerebral Aneurysms ◽

Thin Walled ◽

Unruptured Cerebral Aneurysms

Download Full-text

Computational fluid dynamics (CFD) analysis using porous media modeling predicts angiographic occlusion status after coiling of unruptured cerebral aneurysms—Preliminary study

Journal of Neuroendovascular Therapy ◽

10.5797/jnet.or.2014-0035 ◽

2015 ◽

Vol 9 (2) ◽

pp. 69-77 ◽

Cited By ~ 6

Author(s):

Yasuyuki UMEDA ◽

Fujimaro ISHIDA ◽

Masanori TSUJI ◽

Kazuhiro FURUKAWA ◽

Takanori SANO ◽

...

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Porous Media ◽

Cerebral Aneurysms ◽

Cfd Analysis ◽

Computational Fluid Dynamics Cfd ◽

Preliminary Study ◽

Unruptured Cerebral Aneurysms

Download Full-text

Morphological and Hemodynamic Changes during Cerebral Aneurysm Growth

Brain Sciences ◽

10.3390/brainsci11040520 ◽

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.

Download Full-text

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

BioMed Research International ◽

10.1155/2018/3047181 ◽

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.

Download Full-text