In Vitro Evaluation of Intra-Aneurysmal, Flow-Diverter-Induced Thrombus Formation: A Feasibility Study

Gester, Kathrin; Lüchtefeld, I.; Büsen, Martin; Sonntag, Simon J.; Linde, Torsten; Steinseifer, Ulrich; Cattaneo, Giorgio

doi:10.3174/ajnr.a4555

Cited by 29 publications

(34 citation statements)

References 34 publications

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“…As such, a comprehensive mesh independence study was performed to evaluate any mesh-induced discretisation error in the key metrics used to evaluate device performance. 21 Although less variation is seen in mean-WSS reduction across the aneurysm and device combinations (shown in Figure 8), the differences of 14.6% and 6.5%, for Aneurysms I and III respectively are still notable.…”

Section: Post-processingmentioning

confidence: 87%

Virtual flow-diverter treatment planning: The effect of device placement on bifurcation aneurysm haemodynamics

Peach

Spranger

Ventikos

2016

Proc Inst Mech Eng H

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Bifurcation aneurysms account for a large fraction of cerebral aneurysms and often present morphologies that render traditional endovascular treatments, such as coiling, challenging and problematic. Flow-diverter stents offer a potentially elegant treatment option for such aneurysms, but clinical use of these devices remains controversial. Specifically, the deployment of a flow-diverter device in a bifurcation entails jailing one or more potentially vital vessels with a low-porosity mesh designed to restrict the flow. When multiple device placement configurations exist, the most appropriate clinical decision becomes increasingly opaque. In this study, three bifurcation aneurysm geometries were virtually treated by flow-diverter device. Each aneurysm was selected to offer two possible device deployment positions. Flow-diverters similar to commercially available designs were deployed with a fast-deployment algorithm before transient and steady state computational fluid dynamics simulations were performed. Reductions in aneurysm inflow, mean wall shear stress and maximum wall shear stress, all factors often linked with aneurysm treatment outcome, were compared for different device configurations in each aneurysm. In each of the three aneurysms modelled, a particular preferential device placement was shown to offer superior performance with the greatest reduction in the flow metrics considered. In all the three aneurysm geometries, substantial variations in inflow reduction (up to 25.3%), mean wall shear stress reduction (up to 14.6%) and maximum wall shear stress reduction (up to 12.1%) were seen, which were all attributed to device placement alone. Optimal device placement was found to be non-trivial and highly aneurysm specific; in only one-third of the simulated geometries, the best overall performance was achieved by deploying a device in the daughter vessel with the highest flow rate. Good correspondence was seen between transient results and steady state computations that offered a significant reduction in simulation run time. If accurate steady state computations are combined with the fast-deployment algorithm used, the modest run time and corresponding hardware make a virtual treatment pipeline in the clinical setting a meaningful possibility.

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Section: Post-processingmentioning

confidence: 87%

Virtual flow-diverter treatment planning: The effect of device placement on bifurcation aneurysm haemodynamics

Peach

Spranger

Ventikos

2016

Proc Inst Mech Eng H

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“…In vitro tools which can be used to generate data for validation are desirable as there can be greater control over the experimental process. 16 To date, there have been a large number of in-vitro studies of haemodynamics. 2-4, [11][12][13]17,22,40,41 For both in silico and in vitro setups, the reconstruction of patientspecific anatomical models is beneficial.…”

Section: Introductionmentioning

confidence: 99%

“…Particle image velocimetry (PIV) is an in vitro fluid dynamic measurement method that is commonly used for external and internal flow studies and is particularly useful for bio-fluid flow problems, such as flow in aneurysms. 9,13,16,29,38 Aside from vascular flow, it has also been employed for the investigation of respiratory studies. 14 The majority of flows of medical interest occur in highly complex internal channels.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a Desktop 3D Printed Rigid Refractive-Indexed-Matched Flow Phantom for PIV Measurements on Cerebral Aneurysms

Ngoepe

Jermy

et al. 2019

Cardiovasc Eng Tech

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Purpose-Fabrication of a suitable flow model or phantom is critical to the study of biomedical fluid dynamics using optical flow visualization and measurement methods. The main difficulties arise from the optical properties of the model material, accuracy of the geometry and ease of fabrication. Methods-Conventionally an investment casting method has been used, but recently advancements in additive manufacturing techniques such as 3D printing have allowed the flow model to be printed directly with minimal post-processing steps. This study presents results of an investigation into the feasibility of fabrication of such models suitable for particle image velocimetry (PIV) using a common 3D printing Stereolithography process and photopolymer resin. Results-An idealised geometry of a cerebral aneurysm was printed to demonstrate its applicability for PIV experimentation. The material was shown to have a refractive index of 1.51, which can be refractive matched with a mixture of deionised water with ammonium thiocyanate (NH 4 SCN). The images were of a quality that after applying common PIV pre-processing techniques and a PIV cross-correlation algorithm, the results produced were consistent within the aneurysm when compared to previous studies. Conclusions-This study presents an alternative low-cost option for 3D printing of a flow phantom suitable for flow visualization simulations. The use of 3D printed flow phantoms reduces the complexity, time and effort required compared to conventional investment casting methods by removing the necessity of a multi-part process required with investment casting techniques.

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“…Second, poststent MR imaging measurements were performed shortly after the procedure and did not reflect the entire IA thrombosis evolution influencing both the flow conditions and the neck endothelialization as shown in vitro by Gester et al 40 Consequently, our statements should be weighed carefully, and further studies should be considered to monitor aneurysmal velocity modification during follow-up imaging. Third, our results presented here (based on systolic velocity reduction) are limited among other relevant flow parameters in flow diversion, such as wall shear stress, the stagnation zone, and residence time.…”

Section: Limitationsmentioning

confidence: 99%

How Flow Reduction Influences the Intracranial Aneurysm Occlusion: A Prospective 4D Phase-Contrast MRI Study

Brina¹,

Bouillot

Reymond³

et al. 2019

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE: Flow-diverter stents are widely used for the treatment of wide-neck intracranial aneurysms. Various parameters may influence intracranial aneurysm thrombosis, including the flow reduction induced by flow-diverter stent implantation, which is assumed to play a leading role. However, its actual impact remains unclear due to the lack of detailed intra-aneurysmal flow measurements. This study aimed to clarify this relationship by quantitatively measuring the intra-aneurysmal flow using 4D phase-contrast MR imaging. MATERIALS AND METHODS:We acquired prospective pre-and post-stent implantation 4D phase-contrast MR imaging data of a consecutive series of 23 patients treated with flow-diverter stents. Velocity field data were combined with the intraprocedural 3D angiogram vessel geometries for precise intracranial aneurysm extraction and partial volume correction. Intra-aneurysmal hemodynamic modifications were compared with occlusion outcomes at 6 and 12 months. RESULTS:The averaged velocities at systole were lower after flow-diverter stent implantation for all patients and ranged from 21.7 6 7.1 cm/s before to 7.2 6 2.9 cm/s after stent placement. The velocity reduction was more important for the group of patients with aneurysm thrombosis at 6 months (68.8%) and decreased gradually from 66.2% to 55% for 12-month thrombosis and no thrombosis, respectively (P = .08). CONCLUSIONS:We propose an innovative approach to measure intracranial flow changes after flow-diverter stent implantation. We identified a trend between flow reduction and thrombosis outcome that brings a new insight into current understanding of the flow-diversion treatment response.ABBREVIATIONS: CFD 4 computational fluid dynamics; 3DRA 4 3D rotational angiography; FDS 4 flow-diverter stent; IA 4 intracranial aneurysm;PCMR 4 phase-contrast MRI; PVRR 4 proportional velocity-reduction ratio; Q ICA 4 ICA systolic flow rates ratio; Q ICA 4 ICA mean flow rates; Vel an 4 intraaneurysmal velocity; VENC 4 velocity encoding

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In Vitro Evaluation of Intra-Aneurysmal, Flow-Diverter-Induced Thrombus Formation: A Feasibility Study

Abstract: BACKGROUND AND PURPOSE:Intracranial aneurysm treatment by flow diverters aims at triggering intra-aneurysmal thrombosis. By combining in vitro blood experiments with particle imaging velocimetry measurements, we investigated the time-resolved thrombus formation triggered by flow diverters.

Cited by 29 publications

References 34 publications

Virtual flow-diverter treatment planning: The effect of device placement on bifurcation aneurysm haemodynamics

Virtual flow-diverter treatment planning: The effect of device placement on bifurcation aneurysm haemodynamics

Evaluation of a Desktop 3D Printed Rigid Refractive-Indexed-Matched Flow Phantom for PIV Measurements on Cerebral Aneurysms

How Flow Reduction Influences the Intracranial Aneurysm Occlusion: A Prospective 4D Phase-Contrast MRI Study

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