Abstract 1122‐000063: Postoperative Recanalization Factors of Coil Embolization for Cerebral Aneurysms with Comparable Volume Embolization Ratio

2021 ◽  
Vol 1 (S1) ◽  
Author(s):  
Hayato Uchikawa ◽  
Hiroyuki Takao ◽  
Soichiro Fujimura ◽  
Yuya Uchiyama ◽  
Yuma Yamanaka ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Aneurysm ◽  
High Velocity ◽  
Coil Embolization ◽  
Cerebral Aneurysms ◽  
Mean Value ◽  
Morphological Parameters ◽  
Hemodynamic Parameters ◽  
Concentrated Flow ◽  
Coil Shape

Introduction : Volume embolization ratio (VER) has been reported to be involved in postoperative recanalization of coil embolization. However, despite comparable VER, some cases remained stable, and the others showed recanalization. Hemodynamic and morphological factors, as described in previous studies, may also influence recanalization in addition to VER. In this study, we focused on cerebral aneurysms treated by coil embolization with comparable VER. Blood flow analysis using computational fluid dynamics (CFD) and geometrical measurements were performed to investigate the recanalization factors. Methods : We focused on the aneurysms that underwent coil embolization with 15–20% VER. The criteria for the case selection were that the size of the aneurysms was 5–10 mm and that the aneurysm was treated by only coil (i.e., the stent‐assisted cases were excluded). Aneurysms that recanalized after coil embolization and underwent additional coil deployment were defined as “recanalized”, and aneurysms that remained stable after coil embolization without coil compaction were defined as “stable”. Finally, we selected 7 recanalized cases (ICA: 1, MCA: 3, ACA: 3) and 18 stable cases (ICA: 6, MCA: 3, ACA: 9). CFD analysis and morphometry were performed on the vessel geometry after coil embolization. The coil shape was modeled by the virtual coil technique. We calculated three morphological parameters and 34 hemodynamic parameters, then we compared them between the recanalized and stable cases using the Mann‐Whitney U test to identify recanalization factors. In addition, we reconstructed the coil shape from medical images and compared its structure and flow characters for stable and recanalized cases. Results : The average VER for the cases analyzed in this study were 16.7% for recanalized cases and 17.7% for stable cases. As hemodynamic parameters, the spatially averaged velocity normal to the neck plane into the cerebral aneurysm ( NV neck ), and the ratio of the area where blood flows into the cerebral aneurysm after the coil embolization to the area of the neck surface (inflow area ratio: IAR) showed significant difference. Although the hemodynamic parameters were significantly different, morphological parameters did not show statistically significance. In the recanalized case, NV neck tended to be higher (mean value, recanalized: 0.931, stable: 0.822, P < 0.05), and IAR tended to be lower (mean value, recanalized: 0.319, stable: 0.408, P < 0.01). The high NV neck and low IAR indicate that the aneurysm had concentrated flow with a high velocity at the neck surface. There was the concentrated blood flow with the high velocity that collided with the modeled coil in a CFD result for the recanalized case. The area where the blood flow impinged on the modeled coil coincided with the compacted coil region reconstructed from medical images. Therefore, a large force on the coil indicated by these hemodynamic parameters may cause the postoperative recanalization. Conclusions : Even with the same level of VER, there was a possibility of recanalization in aneurysms with a high velocity and concentrated flow into the aneurysm. It is necessary to consider not only VER but also hemodynamic factors to investigate recanalization factors after the coil embolization.

scholarly journals Computed Tomography Image under Optimized Iterative Reconstruction Algorithm to Analyze the Characteristics of Blood Flow Field in Cerebral Aneurysm before and after Stent Implantation

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Kunyang Bao ◽  
Chao Liu ◽  
Jin Li ◽  
Xiang Liu ◽  
Wenzhang Luo ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Field ◽  
Cerebral Aneurysm ◽  
Iterative Reconstruction ◽  
Stent Implantation ◽  
Cerebral Aneurysms ◽  
Reconstruction Algorithm ◽  
Ct Images ◽  
Iterative Reconstruction Algorithm ◽  
The Difference

In order to analyze the change characteristics of blood flow field in cerebral aneurysms before and after stent implantation, this study first constructed an optimized iterative reconstruction algorithm to reconstruct CT images of patients with cerebral aneurysms and used it to solve the problem of image sharpness. In addition, backprojection image reconstruction algorithm and Fourier transform analytic method were introduced. According to the CT images of cerebral arteries of patients, the lesions were presented in a three-dimensional and visual way through the reconstructed three-dimensional images, thus achieving the effects of simulation and simulation. The results showed that the sensitivity, specificity, and accuracy of the optimized iterative reconstruction algorithm were 90.78%, 83.27%, and 94.82%, which were significantly higher than those of the backprojection image reconstruction algorithm and Fourier transform analysis method, and the difference was statistically significant ( P < 0.05 ). Before operation, the blood flow velocity in the neck of aneurysm was 7.35 × 10−2 m/s, the exit velocity was 1.51 × 10−1 m/s, and the maximum velocity appeared in the upstream part of the exit. After passing through the aneurysm, the blood flow velocity began to decrease gradually, forming a vortex at the top of the tumor. After stent implantation, the neck and outlet velocities of cerebral aneurysm were 9.352 × 10−2 m/s and 1.897 × 10−2 m/s, respectively. The velocity of blood flow decreased after entering the aneurysm, and there was no vortex at the top of the aneurysm. Among the outlet velocities of arterial blood vessels, the velocity before stent implantation was significantly lower than that after stent implantation, and the difference was statistically significant ( P < 0.05 ). Compared with prestent, the shear force distribution on the wall of cerebral aneurysm showed a significant decrease, and the difference was statistically significant ( P < 0.05 ). To sum up, pelvic floor ultrasound based on hybrid iterative reconstruction algorithm has high accuracy in diagnosing the changes of blood flow field in cerebral aneurysms. The application of CT images in the diagnosis of cerebral aneurysms can objectively provide imaging data for clinical practice and has high application value.

Evaluation of Cerebral Aneurysm Stent Performance in a Subject-Specific Computational Model

2010 ◽  
Author(s):  
Timothy J. Gundert ◽  
John F. LaDisa
Keyword(s):  
United States ◽  
Blood Flow ◽  
Computational Model ◽  
Cerebral Aneurysm ◽  
Cerebral Aneurysms ◽  
The United States ◽  
Flow Stagnation ◽  
Subject Specific ◽  
Endovascular Devices ◽  
Saccular Aneurysms

Rupture of cerebral aneurysms is the second leading cause of stroke in the United States [1]. Altered hemodynamics is thought to play a role in the progression and subsequent rupture of aneurysms. Blood flow into an aneurysm can be occluded by surgically clipping the aneurysm or using endovascular devices, such as stents or coils. In saccular aneurysms, coiling alone may be a sufficient method of inducing flow stagnation in the aneurysm, causing thrombosis and preventing rupture. When treating wide-necked aneurysms, stenting is often used in conjunction with coiling to prevent the migration of coils. Many investigators have studied the ability of a stent-only treatment to favorably alter flow in aneurysms [2, 3].

scholarly journals Lyophilizing thrombin powder-based treatment for hemostasis during coil embolization of ruptured cerebral aneurysm: Two case reports

2019 ◽  
Vol 25 (4) ◽  
pp. 454-459
Author(s):  
Changchun Jiang ◽  
Wei Wang ◽  
Baojun Wang ◽  
Yuechun Li ◽  
Guorong Liu ◽  
...  
Keyword(s):  
Cerebral Aneurysm ◽  
Coil Embolization ◽  
Case Reports ◽  
Balloon Catheter ◽  
Treatment Strategies ◽  
Cerebral Aneurysms ◽  
Interventional Therapy ◽  
Parent Artery ◽  
Clinical Practices ◽  
Detachable Coils

Background Rupture of cerebral aneurysm is an inevitable complication during embolization, followed by subsequent acute subarachnoid hemorrhage or intracranial hematoma, and results in the aggravation of a patient’s condition. In particular, for patients who have had a ruptured aneurysm, urgent treatment strategies are required during operation. The most common hemostatic methods seen in clinical practices are as follows: after lowering the blood pressure, we continue to embolize the aneurysms with detachable coils as soon as possible or inject with Glubran/Onyx embolization liquids, as well as use a balloon catheter to temporarily block the blood supply. If the conditions are permissible, a balloon guiding catheter may even be used to restrict the proximal blood flow. At times, due to limitations of these methods, neurosurgeons are requested to perform craniotomy to treat the hemostasis. However, the delayed transition often leads to rapid deterioration of the patient’s condition and even death due to cerebral hernia. Case description We herein presented two cases of ruptured cerebral aneurysms to provide an alternative method for hemostasis and to save the lives of patients as much as possible. In an extremely urgent situation (conventional treatment is ineffective), we successfully saved the patient’s life by injecting lyophilizing thrombin powder (LTP) solution into the aneurysmal sac and the parent artery through a microcatheter. Conclusions To our knowledge, this is the first report of successful hemostasis during coil embolization of ruptured cerebral aneurysm with LTP. Further prospective studies are needed to confirm the safety and efficacy of LTP in cerebrovascular interventional therapy.

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.

The Effects of High Porosity Stent Configurations on Cerebral Aneurysm Hemodynamics

2011 ◽  
Author(s):  
Haithem Babiker ◽  
Justin Ryan ◽  
L. Fernando Gonzalez ◽  
Felipe Albuquerque ◽  
Daniel Collins ◽  
...  
Keyword(s):  
Endovascular Treatment ◽  
Cerebral Aneurysm ◽  
Coil Embolization ◽  
Cerebral Aneurysms ◽  
High Porosity ◽  
Incomplete Filling ◽  
Aneurysmal Neck ◽  
Treatment For Cerebral Aneurysms ◽  
Wide Neck

Coil embolization is the most common endovascular treatment for cerebral aneurysms at many centers [1]. Nevertheless, the coiling of wide-neck aneurysms is a challenge. Incomplete filling of the aneurysmal sac due to coil configuration challenges and aneurysmal growth can often lead to recurrence. To assist treatment with coils, clinicians may deploy a high porosity stent in a staged process to act as a supporting bridge for coils. The stent is first deployed across the aneurysmal neck, and multiple coils are then deployed into the aneurysmal sac 6–8 weeks later [2]. Under certain circumstances, coil deployment is not possible and high porosity stents alone are used for treatment [2–3].

Abstract 1122‐000015: Differences of Morphological and Hemodynamic Rupture Risk Factors in Cerebral Aneurysms Between Pre‐ and Post‐Rupture

2021 ◽  
Vol 1 (S1) ◽  
Author(s):  
Yuma Yamanaka ◽  
Hiroyuki Takao ◽  
Soichiro Fujimura ◽  
Yuya Uchiyama ◽  
Shota Sunami ◽  
...  
Keyword(s):  
Risk Factors ◽  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Cerebral Aneurysms ◽  
Aneurysm Rupture ◽  
Morphological Parameters ◽  
Rupture Risk ◽  
Parent Vessel ◽  
Cfd Simulations

Introduction : Morphological and hemodynamic characteristics have been reported to be involved in the rupture of cerebral aneurysms. Therefore, geometrical measurements of cerebral aneurysms and blood flow analysis using computational fluid dynamics (CFD) have been conducted. Some previous studies investigated the rupture risk factors from cerebral arterial geometries that were taken before the rupture (pre‐rupture), and the others used geometries taken after the rupture (post‐rupture). However, aneurysm rupture may alter arterial geometries and CFD simulation results. The aim of this study is to evaluate the morphological and hemodynamic alternations due to cerebral aneurysm rupture. Methods : We identified 21 cerebral aneurysms (ICA: 9, MCA: 3, ACA: 4, BA: 3, VA: 2) which had ruptured during the follow‐up terms. Each case had at longest two‐years term between the rupture date and the latest angiographic date before the aneurysm rupture (pre‐rupture). The post‐rupture arterial geometries were acquired preoperatively for subarachnoid hemorrhage. We used the arterial geometries reconstructed from computed tomography angiography or digital subtraction angiography images for conducting morphological measurements and CFD simulations. We performed transient blood flow simulations for two heart pulse cycles in the CFD simulations. We obtained five morphological parameters and 24 hemodynamic parameters considered as the rupture risk factors. Finally, we conducted Wilcoxon’s signed‐rank sum test between the parameters obtained from pre‐ and post‐rupture aneurysms to specify altered parameters due to the aneurysm rupture. We also calculated the change rate (CR) based on the value in pre‐rupture for parameters that had a statistical significance to investigate the alternation in detail. Results : The aneurysmal volume ( V ), height ( H ), aspect ratio ( AR ), and spatial averaged, maximum, and minimum wall shear stress of the aneurysm dome normalized by the spatially averaged wall shear stress of the parent vessel ( NWSSave , NWSSmax , and NWSSmin ) were significantly altered between pre‐ and post‐rupture. In particular, the morphological parameters increased after the rupture (average CR of V , H , and AR were 25.8 %, 13.4 %, and 15.9 %, respectively). These results indicate that the aneurysm shapes tended to increase lengthwise after the rupture. On the other hand, the NWSS tended to decrease (average CR of NWSSave , NWSSmax , and NWSSmin  were ‐21.0 %, ‐13.7 %, and ‐22.7 %, respectively). These results imply that the aneurysm rupture altered the aneurysm to a more complicated shape, and thereby the blood flow became stagnated that introduced lower WSS . In contrast, there were some cases in which NWSS increased, and these cases had vasospasm at their parent arteries caused by the rupture (i.e., 5 of 21 cases had vasospasm, and the average CR of NWSSave was 14.1 %). The parent vessel proximal to the aneurysm was shrunk due to the vasospasm, resulting in increased flow velocity and thus increased NWSS . Conclusions : The cerebral aneurysm rupture deformed the aneurysms into longitudinal and led to increased volumes. The NWSSs in CFD simulations using post‐rupture geometries tended to decrease in comparison with pre‐rupture. When studying rupture factors of cerebral aneurysms using geometrical measurements and CFD simulations, special attention should be paid to the clinical image and rupture characteristics standardization criteria.

Development of Stent Strut Pattern for Cerebral Aneurysm

2010 ◽  
Author(s):  
Toshio Nakayama ◽  
Shinkyu Jeong ◽  
Srinivas Karkenahalli ◽  
Makoto Ohta
Keyword(s):  
Blood Flow ◽  
Cerebral Aneurysm ◽  
Cerebral Aneurysms ◽  
Optimization Method ◽  
Flow Speed ◽  
Parent Artery ◽  
Stent Strut ◽  
Computational Fluid Dynamics Cfd ◽  
Commercial Solver ◽  
Volume Method

Background and purpose: Stent implantation (stenting) in intracranial arteries is termed as endovascular treatment. The number of such cases has been increasing worldwide because the surgical damage resulting from stenting seem to be less than that of other treatments. The role of stenting for cerebral aneurysms is to reduce the blood flow speed in cerebral aneurysms. We have developed a computational fluid dynamics (CFD) system using a realistic stent and blood vessel and have studied the effect of the stent. Results of our study showed the stent strut pattern and stenting position to be very effective for reducing the blood flow speed in cerebral aneurysms. We have in describe the designing method used to design the stent strut pattern which reduces both the blood flow speed and the wall shear stress (WSS). Methods: An idealized aneurysm, a parent artery, and various stent shapes were used. The shape of the parent artery was a straight pipe and the aneurysm was a sphere. The stent was implanted in the neck of the aneurysm. The porosity remained of 80%, and the width of the stent strut ranged from 90 to 160[μm]. The stent strut height was fixed at a constant 150 [μm]. For the constructed shape data, a tetrahedron numerical mesh was generated. Calculation using the finite volume method was performed by a commercial solver. The optimization method was applied to the CFD results, and the stent strut patterns that reduced the blood flow speed and the WSS most were determined. Conclusion: The development method of stent strut pattern was proposed. Various stent strut patterns to reduce blood flow speed and WSS in/on cerebral aneurysm were tested. The stent strut pattern that reduced the blood flow speed and that reduced the WSS were determined. In the future works, the number of CFD cases should be increased and the optimal stent strut pattern determined.

Classification of Blood Flow in Cerebral Aneurysm Considering the Parent Artery Curves

2013 ◽  
Author(s):  
Toshio Nakayama ◽  
Shin-ichiro Sugiyama ◽  
Makoto Ohta
Keyword(s):  
Blood Flow ◽  
Flow Pattern ◽  
Cerebral Aneurysm ◽  
Cerebral Aneurysms ◽  
Flow Simulation ◽  
Flow Speed ◽  
Parent Artery ◽  
Blood Flow Pattern ◽  
Stent Strut

Background and purpose: Recently, the number of endovascular treatments has increased worldwide because of advances in minimally invasive surgery. We considered the effect of reduced flow due to stent implantation and proposed the design of stent strut pattern from the viewpoint of fluid dynamics. We developed an optimized stent strut pattern using a computational fluid dynamics (CFD) system. A classification of cerebral aneurysms was proposed using the aspect ratio (AR) and the stent strut pattern was optimized. The results of optimal stent strut pattern for reduced blood flow speed and wall shear stress were different, and the influence of the AR values was small because there was no dependence on relationship between blood flow and the AR values due to the use of a straight pipe in the parent artery. The classification of blood flow pattern in a cerebral aneurysm must consider the parent artery curves. In this study, we investigated the relationship between the blood flow pattern in cerebral aneurysms and parent artery curves using CFD. Methods: To investigate the influence of blood flow based on the parent artery curve, the parent artery shape was constructed as follows. Patient-specific parent artery shape with a cerebral aneurysm was reconstructed using OsiriX. Center line was extracted using a vascular modeling tool kit. The parent artery shape was reconstructed based on this center line using CAD. The diameter of the parent artery was 4 mm. The cerebral aneurysm shape was a combination of a straight pipe and a half sphere, and the AR value was fixed at 1.0. The cerebral aneurysm position varied from the original position to a 180° rotated position. Tetrahedral numerical mesh was generated with a commercial mesh generator (ICEM CFD 14.0; Ansys Inc.) for the CFD analysis. The numerical blood flow simulation was performed on a supercomputer using the commercial ANSYS FLUENT 6.3 software package and the finite volume method, and a steady flow simulation was performed. Boundary conditions were set for velocity at the inlet, pressure at the outlet, no-slip parent artery, and stent surface. Reynolds numbers at the inlet determined from the mean blood flow speed were 240 and 600. Results and discussion: In this study, we revealed the blood flow pattern in some cerebral aneurysms using CFD. The pattern in a cerebral aneurysm was influenced by the aneurysm direction and parent artery curves. The blood flow pattern in a neck cerebral aneurysm was classified into two types.

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.

scholarly journals A new combined parameter predicts re-treatment for coil-embolized aneurysms: a computational fluid dynamics multivariable analysis study

2017 ◽  
Vol 10 (8) ◽  
pp. 791-796 ◽  
Author(s):  
Soichiro Fujimura ◽  
Hiroyuki Takao ◽  
Takashi Suzuki ◽  
Chihebeddine Dahmani ◽  
Toshihiro Ishibashi ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Coil Embolization ◽  
Multivariable Analysis ◽  
Cerebral Aneurysms ◽  
Clinical Information ◽  
Patient Specific ◽  
Slight Reduction ◽  
Clinical Parameters ◽  
Basic Fluid

PurposeCoil embolization is a minimally invasive method used to treat cerebral aneurysms. Although this endovascular treatment has a high success rate, aneurysmal re-treatment due to recanalization remains a major problem of this method. The purpose of this study was to determine a combined parameter that can be useful for predicting aneurysmal re-treatment due to recanalization.MethodsPatient-specific geometries were used to retrospectively analyze the blood flow for 26 re-treated and 74 non-retreated aneurysms. Post-operatively aneurysms were evaluated at 12-month follow-up. The hemodynamic differences between the re-treatment and non-retreatment aneurysms were analyzed before and after coil embolization using computation fluid dynamics. Basic fluid characteristics, rates of change, morphological factors of aneurysms and patient-specific clinical information were examined. Multivariable analysis and logistic regression analysis were performed to determine a combined parameter—re-treatment predictor (RP).ResultsAmong examined hemodynamic, morphological, and clinical parameters, slight reduction of blood flow velocity rate in the aneurysm, slight increase of pressure rate at the aneurysmal neck and neck area, and hypertension were the main factors contributing to re-treatment. Notably, hemodynamic parameters between re-treatment and non-retreatment groups before embolization were similar: however, we observed significant differences between the groups in the post-embolization average velocity and the rate of reduction in this velocity in the aneurysmal dome.ConclusionsThe combined parameter, RP, which takes into consideration hemodynamic, morphological, and clinical parameters, accurately predicts aneurysm re-treatment. Calculation of RP before embolization may be able to predict the aneurysms that will require re-treatment.

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