1
|
Hariri S, Mirzaei Poueinak M, Hassanvand A, Barzegar Gerdroodbary M, Faraji M. Effects of blood hematocrit on performance of endovascular coiling for treatment of middle cerebral artery (MCA) aneurysms: Computational study. INTERDISCIPLINARY NEUROSURGERY 2023. [DOI: 10.1016/j.inat.2023.101729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
|
2
|
Fast virtual coiling algorithm for intracranial aneurysms using pre-shape path planning. Comput Biol Med 2021; 134:104496. [PMID: 34077817 DOI: 10.1016/j.compbiomed.2021.104496] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 09/30/2022]
Abstract
To aid in predicting and improving treatment outcome of endovascular coiling of intracranial aneurysms, simulation of patient-specific coil deployment should be both accurate and fast. We developed a fast virtual coiling algorithm called Pre-shape Path Planning (P3). It captures the mechanical propensity of a released coil to restore its pre-shape for bending energy minimization, producing coils without unrealistic kinks and bends. A coil is discretized into finite-length segments and extruded from the delivery catheter segment-by-segment following a generic coil pre-shape. With the release of each segment, coil-wall and coil-coil collisions are detected and resolved. Modeling of each case took seconds to minutes. To test the algorithm, we evaluated its output against the literature, experiments, and patient angiograms. The periphery-to-core ratio of coils deployed by P3 decreased with increasing coil packing density, consistent with observations in the literature. Coils deployed by P3 compared well with in vitro experiments, free from unphysical kinks and loops that arose from previous virtual coiling algorithms. Simulations of coiling in four patient-specific aneurysms agreed well with the patient angiograms. To test the influence of coil pre-shape on P3, we performed hemodynamic simulations in aneurysms with coils deployed by P3 using the generic pre-shape, P3 using a coil-specific pre-shape, and full finite-element-method simulation. We found that the generic pre-shape was sufficient to produce results comparable to virtual coiling by finite element modeling. Based on these findings, P3 can rapidly simulate coiling in patient-specific aneurysms with good accuracy and is thus a potential candidate for clinical treatment planning.
Collapse
|
3
|
Chivukula VK, Marsh L, Chassagne F, Barbour MC, Kelly CM, Levy S, Geindreau C, Roscoat SRD, Kim LJ, Levitt MR, Aliseda A. Lagrangian Trajectory Simulation of Platelets and Synchrotron Microtomography Augment Hemodynamic Analysis of Intracranial Aneurysms Treated With Embolic Coils. J Biomech Eng 2021; 143:1102198. [PMID: 33665669 DOI: 10.1115/1.4050375] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Indexed: 11/08/2022]
Abstract
As frequency of endovascular treatments for intracranial aneurysms increases, there is a growing need to understand the mechanisms for coil embolization failure. Computational fluid dynamics (CFD) modeling often simplifies modeling the endovascular coils as a homogeneous porous medium (PM), and focuses on the vascular wall endothelium, not considering the biomechanical environment of platelets. These assumptions limit the accuracy of computations for treatment predictions. We present a rigorous analysis using X-ray microtomographic imaging of the coils and a combination of Lagrangian (platelet) and Eulerian (endothelium) metrics. Four patient-specific, anatomically accurate in vitro flow phantoms of aneurysms are treated with the same patient-specific endovascular coils. Synchrotron tomography scans of the coil mass morphology are obtained. Aneurysmal hemodynamics are computationally simulated before and after coiling, using patient-specific velocity/pressure measurements. For each patient, we analyze the trajectories of thousands of platelets during several cardiac cycles, and calculate residence times (RTs) and shear exposure, relevant to thrombus formation. We quantify the inconsistencies of the PM approach, comparing them with coil-resolved (CR) simulations, showing the under- or overestimation of key hemodynamic metrics used to predict treatment outcomes. We fully characterize aneurysmal hemodynamics with converged statistics of platelet RT and shear stress history (SH), to augment the traditional wall shear stress (WSS) on the vascular endothelium. Incorporating microtomographic scans of coil morphology into hemodynamic analysis of coiled intracranial aneurysms, and augmenting traditional analysis with Lagrangian platelet metrics improves CFD predictions, and raises the potential for understanding and clinical translation of computational hemodynamics for intracranial aneurysm treatment outcomes.
Collapse
Affiliation(s)
| | - Laurel Marsh
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195
| | - Fanette Chassagne
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195
| | - Michael C Barbour
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195
| | - Cory M Kelly
- Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195
| | - Samuel Levy
- Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195
| | - Christian Geindreau
- Laboratoire 3SR, Université Grenoble Alpes, 1270 Rue de la Piscine, Gières 38610, France
| | | | - Louis J Kim
- Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195; Department of Radiology, University of Washington, Seattle, WA 98195
| | - Michael R Levitt
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195; Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195; Department of Radiology, University of Washington, Seattle, WA 98195
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195; Department of Neurological Surgery, University of Washington, Seattle, WA 98195; Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA 98195
| |
Collapse
|
4
|
Jang LK, Alvarado JA, Pepona M, Wasson EM, Nash LD, Ortega JM, Randles A, Maitland DJ, Moya ML, Hynes WF. Three-dimensional bioprinting of aneurysm-bearing tissue structure for endovascular deployment of embolization coils. Biofabrication 2020; 13. [DOI: 10.1088/1758-5090/abbb9b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 09/25/2020] [Indexed: 01/30/2023]
|
5
|
Intra-aneurysmal pressure changes during stent-assisted coiling. PLoS One 2020; 15:e0233981. [PMID: 32497124 PMCID: PMC7272096 DOI: 10.1371/journal.pone.0233981] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 05/16/2020] [Indexed: 01/14/2023] Open
Abstract
We aimed to examine aneurysm hemodynamics with intra-saccular pressure measurement, and compare the effects of coiling, stenting and stent-assisted coiling in proximal segments of intracranial circulation. A cohort of 45 patients underwent elective endovascular coil embolization (with or without stent) for intracranial aneurysm at our department. Arterial pressure transducer was used for all measurements. It was attached to proximal end of the microcatheter. Measurements were taken in the parent artery before and after embolization, at the aneurysm dome before embolization, after stent implantation, and after embolization. Stent-assisted coiling was performed with 4 different stents: LVIS and LVIS Jr (Microvention, Tustin, CA, USA), Leo (Balt, Montmorency, France), Barrel VRD (Medtronic/ Covidien, Irvine, CA, USA). Presence of the stent showed significant reverse correlation with intra-aneurysmal pressure–both systolic and diastolic—after its implantation (r = -0.70 and r = -0.75, respectively), which was further supported by correlations with stent cell size–r = 0.72 and r = 0.71, respectively (P<0.05). Stent implantation resulted in significant decrease in diastolic intra-aneurysmal pressure (p = 0.046). Systolic or mean intra-aneurysmal pressure did not differ significantly. Embolization did not significantly change the intra-aneurysmal pressure in matched pairs, regardless of the use of stent (p>0.05). In conclusion, low-profile braided stents show a potential to divert blood flow, there was significant decrease in diastolic pressure after stent placement. Flow-diverting properties were related to stent porosity. Coiling does not significantly change the intra-aneurysmal pressure, regardless of packing density.
Collapse
|
6
|
Pichamuthu J, Feroze R, Chung T, Jankowitz B, Vorp DA. CEREBRAL ANEURYSM WALL STRESS AFTER COILING DEPENDS ON MORPHOLOGY AND COIL PACKING DENSITY. J Biomech Eng 2019; 141:2738328. [PMID: 31294748 DOI: 10.1115/1.4044214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Indexed: 11/08/2022]
Abstract
Endovascular coil embolization is widely used to treat cerebral aneurysms as an alternative to surgical clipping. It involves filling the aneurysmal sac with metallic coils to promote the formation of a coil/thrombus mass (CTM) to protect the aneurysm wall from hemodynamic forces and prevents rupture. A significant number of aneurysms are incompletely coiled leading to aneurysm regrowth and/or recanalization. Porcine blood and platinum coils were used to construct an in-vitro CTM for uniaxial compression testing with coil packing densities (CPDs) of 10%, 20%, and 30%. Mechanical properties for each case were derived and used in finite element simulations of patient specific 3D reconstructions of aneurysms with simple or complex geometries. Reproducible stress/strain curves were obtained from compression testing of CTM and predicted by a polynomial mechanical response function. An exponential increase in the CTM stiffness was observed with increasing CPD. Elevated wall stresses were found throughout the aneurysm dome, neck, and parent artery in simulations of the aneurysms with no filling. Complete, 100% filling of the aneurysms with whole blood clot and CPDs of 10%, 20%, and 30% significantly reduced mean wall stress (MWS) in simple and complex geometry aneurysms. Sequential increases in CPD resulted in significantly greater increases in MWS in simple but not complex geometry aneurysms. These results provide a quantitative measure of the degree to which CPD impacts wall stress and suggest that complex aneurysmal geometries may be more resistant to coil embolization treatment.
Collapse
Affiliation(s)
- Joseph Pichamuthu
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA; Center for Vascular Remodeling and Regeneration, University of Pittsburgh, Pittsburgh, PA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Rafey Feroze
- Department of Neurosurgery, University of Pittsburgh, Pittsburgh, PA
| | - Timothy Chung
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA
| | - Brian Jankowitz
- Department of Neurosurgery, University of Pittsburgh, Pittsburgh, PA
| | - David A Vorp
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA; Center for Vascular Remodeling and Regeneration, University of Pittsburgh, Pittsburgh, PA; Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, PA; Department of Surgery, University of Pittsburgh, Pittsburgh, PA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA; Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA; Clinical and Translational Sciences Institute, University of Pittsburgh, Pittsburgh, PA
| |
Collapse
|
7
|
Otani T, Shindo T, Ii S, Hirata M, Wada S. Effect of Local Coil Density on Blood Flow Stagnation in Densely Coiled Cerebral Aneurysms: A Computational Study Using a Cartesian Grid Method. J Biomech Eng 2018; 140:2671737. [DOI: 10.1115/1.4039150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Indexed: 11/08/2022]
Abstract
Aneurysm recurrence is the most critical concern following coil embolization of a cerebral aneurysm. Adequate packing density (PD) and coil uniformity are believed necessary to achieve sufficient flow stagnation, which decreases the risk of aneurysm recurrence. The effect of coil distribution on the extent of flow stagnation, however, especially in cases of dense packing (high PD), has received less attention. Thus, the cause of aneurysm recurrence despite dense packing is still an open question. The primary aim of this study is to evaluate the effect of local coil density on the extent of blood flow stagnation in densely coiled aneurysms. For this purpose, we developed a robust computational framework to determine blood flow using a Cartesian grid method, by which the complex fluid pathways in coiled aneurysms could be flexibly treated using an implicit function. This tool allowed us to conduct blood flow analyses in two patient-specific geometries with 50 coil distribution patterns in each aneurysm at clinically adequate PD. The results demonstrated that dense packing in the aneurysm may not necessarily block completely the inflow into the aneurysm and local flow that formed in the neck region, whose strength was inversely related to this local PD. This finding suggests that local coil density in the neck region still plays an important role in disturbing the remaining local flow, which possibly prevents thrombus formation in a whole aneurysm sac, increasing the risk of aneurysm regrowth and subsequent recurrence.
Collapse
Affiliation(s)
- Tomohiro Otani
- Mem. ASME Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyamacho, Toyonaka-shi 560-8531, Osaka, Japan e-mail:
| | - Takuya Shindo
- Department of Systems Science, School of Engineering Science, Osaka University, 1-3 Machikaneyamacho, Toyonaka-shi 560-8531, Osaka, Japan e-mail:
| | - Satoshi Ii
- Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyamacho, Toyonaka-shi 560-8531, Osaka, Japan e-mail:
| | - Masayuki Hirata
- Department of Neurosurgery, Graduate School of Medicine and Global Center for Medical Engineering and Informatics (MEI Center), Osaka University, 2-2 Yamadaoka, Suita-shi 560-0871, Osaka, Japan e-mail:
| | - Shigeo Wada
- Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyamacho, Toyonaka-shi 560-8531, Osaka, Japan e-mail:
| |
Collapse
|
8
|
Sarrami-Foroushani A, Lassila T, Frangi AF. Virtual endovascular treatment of intracranial aneurysms: models and uncertainty. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 9. [PMID: 28488754 DOI: 10.1002/wsbm.1385] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/09/2017] [Accepted: 02/07/2017] [Indexed: 01/11/2023]
Abstract
Virtual endovascular treatment models (VETMs) have been developed with the view to aid interventional neuroradiologists and neurosurgeons to pre-operatively analyze the comparative efficacy and safety of endovascular treatments for intracranial aneurysms. Based on the current state of VETMs in aneurysm rupture risk stratification and in patient-specific prediction of treatment outcomes, we argue there is a need to go beyond personalized biomechanical flow modeling assuming deterministic parameters and error-free measurements. The mechanobiological effects associated with blood clot formation are important factors in therapeutic decision making and models of post-treatment intra-aneurysmal biology and biochemistry should be linked to the purely hemodynamic models to improve the predictive power of current VETMs. The influence of model and parameter uncertainties associated to each component of a VETM is, where feasible, quantified via a random-effects meta-analysis of the literature. This allows estimating the pooled effect size of these uncertainties on aneurysmal wall shear stress. From such meta-analyses, two main sources of uncertainty emerge where research efforts have so far been limited: (1) vascular wall distensibility, and (2) intra/intersubject systemic flow variations. In the future, we suggest that current deterministic computational simulations need to be extended with strategies for uncertainty mitigation, uncertainty exploration, and sensitivity reduction techniques. WIREs Syst Biol Med 2017, 9:e1385. doi: 10.1002/wsbm.1385 For further resources related to this article, please visit the WIREs website.
Collapse
Affiliation(s)
- Ali Sarrami-Foroushani
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
| | - Toni Lassila
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
| | - Alejandro F Frangi
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), The University of Sheffield, Sheffield, UK
| |
Collapse
|
9
|
Doron O, Cohen JE, Gomori M, Spektor S. Extensive bone erosion caused by pseudotumoral aneurysm growth. J Clin Neurosci 2016; 36:54-56. [PMID: 27842796 DOI: 10.1016/j.jocn.2016.10.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/15/2016] [Indexed: 11/18/2022]
Abstract
Carotid ophthalmic aneurysms constitute 0.9-6.5% of the aneurysms of the ICA with up to 20% of the cases presenting with visual symptoms. We report a case of an adult woman, presented with chronic headaches and protracted visual alterations progressing to left eye amaurosis. Neuroradiological exams, revealed a giant partially thrombosed carotid ophthalmic aneurysm extending anteriorly, causing pseudotumoral spheno-orbital bone erosion. The patient underwent surgical clipping, evacuation of the thrombotic mass and decompression of the optic pathways with rapid recovery of the vision. This unusual case, contributes to the available body of evidence on aneurysms growth.
Collapse
Affiliation(s)
- Omer Doron
- Department of Neurosurgery, Hadassah University Medical Center, Affiliated to the Hebrew University and Hadassah Medical School, Jerusalem, Israel.
| | - Jose E Cohen
- Department of Neurosurgery, Hadassah University Medical Center, Affiliated to the Hebrew University and Hadassah Medical School, Jerusalem, Israel
| | - Moshe Gomori
- Department of Radiology, Hadassah University Medical Center, Affiliated to the Hebrew University and Hadassah Medical School, Jerusalem, Israel
| | - Sergey Spektor
- Department of Neurosurgery, Hadassah University Medical Center, Affiliated to the Hebrew University and Hadassah Medical School, Jerusalem, Israel
| |
Collapse
|
10
|
Otani T, Ii S, Shigematsu T, Fujinaka T, Hirata M, Ozaki T, Wada S. Computational study for the effects of coil configuration on blood flow characteristics in coil-embolized cerebral aneurysm. Med Biol Eng Comput 2016; 55:697-710. [DOI: 10.1007/s11517-016-1541-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 06/29/2016] [Indexed: 11/28/2022]
|
11
|
Levitt MR, Barbour MC, Rolland du Roscoat S, Geindreau C, Chivukula VK, McGah PM, Nerva JD, Morton RP, Kim LJ, Aliseda A. Computational fluid dynamics of cerebral aneurysm coiling using high-resolution and high-energy synchrotron X-ray microtomography: comparison with the homogeneous porous medium approach. J Neurointerv Surg 2016; 9:0. [PMID: 27405312 DOI: 10.1136/neurintsurg-2016-012479] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 06/21/2016] [Accepted: 06/27/2016] [Indexed: 11/04/2022]
Abstract
BACKGROUND Computational modeling of intracranial aneurysms provides insights into the influence of hemodynamics on aneurysm growth, rupture, and treatment outcome. Standard modeling of coiled aneurysms simplifies the complex geometry of the coil mass into a homogeneous porous medium that fills the aneurysmal sac. We compare hemodynamics of coiled aneurysms modeled from high-resolution imaging with those from the same aneurysms modeled following the standard technique, in an effort to characterize sources of error from the simplified model. MATERIALS Physical models of two unruptured aneurysms were created using three-dimensional printing. The models were treated with coil embolization using the same coils as those used in actual patient treatment and then scanned by synchrotron X-ray microtomography to obtain high-resolution imaging of the coil mass. Computational modeling of each aneurysm was performed using patient-specific boundary conditions. The coils were modeled using the simplified porous medium or by incorporating the X-ray imaged coil surface, and the differences in hemodynamic variables were assessed. RESULTS X-ray microtomographic imaging of coils and incorporation into computational models were successful for both aneurysms. Porous medium calculations of coiled aneurysm hemodynamics overestimated intra-aneurysmal flow, underestimated oscillatory shear index and viscous dissipation, and over- or underpredicted wall shear stress (WSS) and WSS gradient compared with X-ray-based coiled computational fluid dynamics models. CONCLUSIONS Computational modeling of coiled intracranial aneurysms using the porous medium approach may inaccurately estimate key hemodynamic variables compared with models incorporating high-resolution synchrotron X-ray microtomographic imaging of complex aneurysm coil geometry.
Collapse
Affiliation(s)
- Michael R Levitt
- Department of Neurological Surgery, University of Washington, Seattle, Washington, USA.,Department of Radiology, University of Washington, Seattle, Washington, USA.,Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
| | - Michael C Barbour
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
| | | | - Christian Geindreau
- Laboratoire 3SR, UMR 5521, CNRS, Université Grenoble Alpes, Grenoble INP, Grenoble, France
| | - Venkat K Chivukula
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
| | - Patrick M McGah
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
| | - John D Nerva
- Department of Neurological Surgery, University of Washington, Seattle, Washington, USA
| | - Ryan P Morton
- Department of Neurological Surgery, University of Washington, Seattle, Washington, USA
| | - Louis J Kim
- Department of Neurological Surgery, University of Washington, Seattle, Washington, USA.,Department of Radiology, University of Washington, Seattle, Washington, USA
| | - Alberto Aliseda
- Department of Neurological Surgery, University of Washington, Seattle, Washington, USA.,Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
| |
Collapse
|
12
|
Park W, Song Y, Park KJ, Koo HW, Yang K, Suh DC. Hemodynamic Characteristics Regarding Recanalization of Completely Coiled Aneurysms: Computational Fluid Dynamic Analysis Using Virtual Models Comparison. Neurointervention 2016; 11:30-6. [PMID: 26958410 PMCID: PMC4781914 DOI: 10.5469/neuroint.2016.11.1.30] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 02/25/2016] [Indexed: 11/24/2022] Open
Abstract
Purpose Hemodynamic factors are considered to play an important role in initiation and progression of the recurrence after endosaccular coiling of the intracranial aneurysms. We made paired virtual models of completely coiled aneurysms which were subsequently recanalized and compared to identify hemodynamic characteristics related to the recurred aneurysmal sac. Materials and Methods We created paired virtual models of computational fluid dynamics (CFD) in five aneurysms which were initially regarded as having achieved complete occlusion and then recurred during follow-up. Paired virtual models consisted of the CFD model of 3D rotational angiography obtained in the recurred aneurysm and the control model of the initial, parent artery after artificial removal of the coiled and recanalized aneurysm. Using the CFD analysis of the virtual model, we analyzed the hemodynamic characteristics on the neck of each aneurysm before and after its recurrence. Results High wall shear stress (WSS) was identified at the cross-sectionally identified aneurysm neck at which recurrence developed in all cases. A small vortex formation with relatively low velocity in front of the neck was also identified in four cases. The aneurysm recurrence locations corresponded to the location of high WSS and/or small vortex formation. Conclusion Recanalized aneurysms revealed increased WSS and small vortex formation at the cross-sectional neck of the aneurysm. This observation may partially explain the hemodynamic causes of future recanalization after coil embolization.
Collapse
Affiliation(s)
- Wonhyoung Park
- Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.; Department of Neurosurgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Yunsun Song
- Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Kye Jin Park
- Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Hae-Won Koo
- Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Kuhyun Yang
- Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Dae Chul Suh
- Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| |
Collapse
|
13
|
Chen Y, Jankowitz BT, Cho SK, Yeo WH, Chun Y. A novel low-profile flow sensor for monitoring of hemodynamics in cerebral aneurysm. ACTA ACUST UNITED AC 2015. [DOI: 10.12989/bme.2015.2.2.071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
14
|
Goubergrits L, Schaller J, Kertzscher U, Woelken T, Ringelstein M, Spuler A. Hemodynamic impact of cerebral aneurysm endovascular treatment devices: coils and flow diverters. Expert Rev Med Devices 2014; 11:361-73. [PMID: 24918904 DOI: 10.1586/17434440.2014.925395] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Coils and flow diverters or stents are devices successfully used to treat cerebral aneurysms. Treatment aims to reduce intra-aneurysmal flow, thereby separating the aneurysmal sac from the blood circulation. The focus and this manuscript combining literature review and our original research is an analysis of changes in aneurysmal hemodynamics caused by endovascular treatment devices. Knowledge of post-treatment hemodynamics is a path to successful long-term treatment. Summarizing findings on hemodynamic impact of treatment devices, we conclude: coiling and stenting do not affect post-treatment intra-aneurysmal pressure, but significantly alter aneurysmal hemodynamics through flow reduction and a change in flow structure. The impact of treatment devices on aneurysmal flow depends, however, on a set of parameters including device geometry, course of placement, parent vessel and aneurysm geometry.
Collapse
Affiliation(s)
- Leonid Goubergrits
- Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | | | | | | | | | | |
Collapse
|
15
|
Contrast Agent Bolus Dispersion in a Realistic Coronary Artery Geometry: Influence of Outlet Boundary Conditions. Ann Biomed Eng 2013; 42:787-96. [DOI: 10.1007/s10439-013-0950-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 11/19/2013] [Indexed: 01/02/2023]
|
16
|
Mitsos AP, Giannakopoulou MD, Kaklamanos IG, Kapritsou M, Konstantinou MI, Fotis T, Mamoura KV, Mariolis-Sapsakos T, Ntountas IT, Konstantinou EA. Endovascular treatment of cerebral aneurysms in relation to their parent artery wall: a single center study. Neuroradiol J 2013; 26:71-9. [PMID: 23859171 DOI: 10.1177/197140091302600112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Accepted: 12/13/2012] [Indexed: 11/17/2022] Open
Abstract
We report our two-year experience in the endovascular treatment of brain aneurysms in relation to their parent artery wall. We prospectively recorded patients with intracranial aneurysms (107 ruptured - 38 unruptured) treated with coiling during a two-year period: 145 patients, 94 females and 51 males - mean age 56 years. The aneurysms were divided into side-wall (A) and bifurcation (B) groups. A total occlusion rate was noted in post-embolization angiograms in 101 aneurysms (70%) with a morbidity of 4%. No angiographic recurrence arose in the six-month follow-up. The two groups had a similar total occlusion rate (68.31% and 71.8% respectively), while the complication rate was 3% in group A and 4.7% in group B. Significant differences between the two groups were noted in the number of assisted coiling cases: 28 out of 60 cases (46.7%) in group A - 14 out of 85 cases (16.5%) in group B. Further statistical analysis showed strong dependencies for the type of endovascular procedure between the ruptured and unruptured aneurysms in both groups (p 0.000<0.05), but no dependencies between the aneurysm occlusion rate and the ruptured or non-ruptured aneurysms, or between the occlusion rate and the type of endovascular procedure (p 0.552>0.05 and 0.071>0.05 respectively). In conclusion, the anatomic relation of the aneurysm sac with the wall of the parent artery is important, as significant differences in endovascular practice, devices and techniques were noted between side-wall and bifurcation aneurysms.
Collapse
|
17
|
Graziano F, Russo VM, Wang W, Khismatullin D, Ulm AJ. 3D computational fluid dynamics of a treated vertebrobasilar giant aneurysm: a multistage analysis. AJNR Am J Neuroradiol 2013; 34:1387-94. [PMID: 23306008 DOI: 10.3174/ajnr.a3373] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The treatment of giant aneurysms of the vertebrobasilar junction remains a challenging task in neurosurgical practice, and the reference standard therapy is still under debate. Through a detailed postmortem study, we analyzed the hemodynamic factors underlying the formation and recanalization of an aneurysm located at this particular site and its anatomic configuration. METHODS An adult fixed cadaveric specimen with a known VBJ GA, characterized radiographically and treated with endovascular embolization, was studied. 3D computational fluid dynamic models were built based on the specific angioarchitecture of the specimen, and each step of the endovascular treatment was simulated. RESULTS The 3D CFD study showed an area of hemodynamic stress (high wall shear stress, high static pressure, high flow velocity) at the neck region of the aneurysm, matching the site of recanalization seen during the treatment period. CONCLUSIONS Aneurysm morphologic features, location, and patient-specific angioarchitecture are the principal factors to be considered in the management of VBJ giant aneurysms. The 3D CFD study has suggested that, in the treatment of giant aneurysms, the intra-aneurysmal environment induced by partial coil or Onyx embolization may lead to hemodynamic stress at the neck region, potentially favoring recanalization of the aneurysm.
Collapse
Affiliation(s)
- F Graziano
- Clinica Neurochirurgica, AOU G. Rodolico Universita' degli Studi di Catania, Italy.
| | | | | | | | | |
Collapse
|
18
|
Jeong W, Han MH, Rhee K. Effects of framing coil shape, orientation, and thickness on intra-aneurysmal flow. Med Biol Eng Comput 2013; 51:981-90. [DOI: 10.1007/s11517-013-1073-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 03/29/2013] [Indexed: 11/30/2022]
|
19
|
Otani T, Nakamura M, Fujinaka T, Hirata M, Kuroda J, Shibano K, Wada S. Computational fluid dynamics of blood flow in coil-embolized aneurysms: effect of packing density on flow stagnation in an idealized geometry. Med Biol Eng Comput 2013; 51:901-10. [PMID: 23529587 DOI: 10.1007/s11517-013-1062-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 03/10/2013] [Indexed: 11/30/2022]
Abstract
Coil embolization is performed to induce flow stagnation in cerebral aneurysms and enhance blood clot formation, thus preventing rupture and further growth. We investigated hemodynamics in differently positioned aneurysms coiled at various packing densities to determine the effective packing density in terms of flow stagnation. As a first step, hemodynamic simulations were conducted for idealized geometries of both terminal- and sidewall-type aneurysms. Porous media modeling was employed to describe blood flow in coil-embolized aneurysms. The stagnant volume ratio (SVR) was analyzed to quantify the efficacy of coil embolization. Regardless of aneurysm type and angle, SVR increased with increasing packing density, but the increase in SVR varied depending on type. For sidewall-type aneurysms, the packing density required to achieve 60 % SVR was 20 %, roughly independent of aneurysm angle; flow stagnation was achieved at low packing density. In contrast, in terminal-type aneurysms, the packing density required to achieve 60 % SVR was highly dependent on aneurysm angle, accomplishing a 20 % packing density only for lower angles. Indications are that a relatively high packing density would be required, particularly when these aneurysms are angled against the parent artery. The packing density required for flow stagnation varies depending on aneurysm type and relative position.
Collapse
Affiliation(s)
- Tomohiro Otani
- Graduate School of Engineering Science, Osaka University, Machikaneyama-chou 1-3, Toyonaka, Osaka 560-8531, Japan
| | | | | | | | | | | | | |
Collapse
|
20
|
Computer Simulations in Stroke Prevention: Design Tools and Virtual Strategies Towards Procedure Planning. Cardiovasc Eng Technol 2013. [DOI: 10.1007/s13239-013-0134-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
21
|
3D cerebrovascular segmentation combining fuzzy vessel enhancement and level-sets with anisotropic energy weights. Magn Reson Imaging 2013; 31:262-71. [DOI: 10.1016/j.mri.2012.07.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 11/20/2022]
|
22
|
Virtual treatment of basilar aneurysms using shape memory polymer foam. Ann Biomed Eng 2013; 41:725-43. [PMID: 23329002 DOI: 10.1007/s10439-012-0719-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 11/30/2012] [Indexed: 10/27/2022]
Abstract
Numerical simulations are performed on patient-specific basilar aneurysms that are treated with shape memory polymer (SMP) foam. In order to assess the post-treatment hemodynamics, two modeling approaches are employed. In the first, the foam geometry is obtained from a micro-CT scan and the pulsatile blood flow within the foam is simulated for both Newtonian and non-Newtonian viscosity models. In the second, the foam is represented as a porous media continuum, which has permeability properties that are determined by computing the pressure gradient through the foam geometry over a range of flow speeds comparable to those of in vivo conditions. Virtual angiography and additional post-processing demonstrate that the SMP foam significantly reduces the blood flow speed within the treated aneurysms, while eliminating the high-frequency velocity fluctuations that are present within the pre-treatment aneurysms. An estimation of the initial locations of thrombus formation throughout the SMP foam is obtained by means of a low fidelity thrombosis model that is based upon the residence time and shear rate of blood. The Newtonian viscosity model and the porous media model capture similar qualitative trends, though both yield a smaller volume of thrombus within the SMP foam.
Collapse
|
23
|
Morales HG, Larrabide I, Geers AJ, San Román L, Blasco J, Macho JM, Frangi AF. A virtual coiling technique for image-based aneurysm models by dynamic path planning. IEEE TRANSACTIONS ON MEDICAL IMAGING 2013; 32:119-129. [PMID: 23008248 DOI: 10.1109/tmi.2012.2219626] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Computational algorithms modeling the insertion of endovascular devices, such as coil or stents, have gained an increasing interest in recent years. This scientific enthusiasm is due to the potential impact that these techniques have to support clinicians by understanding the intravascular hemodynamics and predicting treatment outcomes. In this work, a virtual coiling technique for treating image-based aneurysm models is proposed. A dynamic path planning was used to mimic the structure and distribution of coils inside aneurysm cavities, and to reach high packing densities, which is desirable by clinicians when treating with coils. Several tests were done to evaluate the performance on idealized and image-based aneurysm models. The proposed technique was validated using clinical information of real coiled aneurysms. The virtual coiling technique reproduces the macroscopic behavior of inserted coils and properly captures the densities, shapes and coil distributions inside aneurysm cavities. A practical application was performed by assessing the local hemodynamic after coiling using computational fluid dynamics (CFD). Wall shear stress and intra-aneurysmal velocities were reduced after coiling. Additionally, CFD simulations show that coils decrease the amount of contrast entering the aneurysm and increase its residence time.
Collapse
Affiliation(s)
- Hernán G Morales
- Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Information and Communications Technologies Department, Universitat Pompeu Fabra (UPF), Barcelona, Spain.
| | | | | | | | | | | | | |
Collapse
|
24
|
Cito S, Ahn YC, Pallares J, Duarte RM, Chen Z, Madou M, Katakis I. Visualization and measurement of capillary-driven blood flow using spectral domain optical coherence tomography. MICROFLUIDICS AND NANOFLUIDICS 2012; 13:227-237. [PMID: 23795150 PMCID: PMC3689301 DOI: 10.1007/s10404-012-0950-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Capillary-driven flow (CD-flow) in microchannels plays an important role in many microfluidic devices. These devices, the most popular being those based in lateral flow, are becoming increasingly used in health care and diagnostic applications. CD-flow can passively pump biological fluids as blood, serum or plasma, in microchannels and it can enhance the wall mass transfer by exploiting the convective effects of the flow behind the meniscus. The flow behind the meniscus has not been experimentally identified up to now because of the lack of high-resolution, non-invasive, cross-sectional imaging means. In this study, spectral-domain Doppler optical coherence tomography is used to visualize and measure the flow behind the meniscus in CD-flows of water and blood. Microchannels of polydimethylsiloxane and glass with different cross-sections are considered. The predictions of the flow behind the meniscus of numerical simulations using the power-law model for non-Newtonian fluids are in reasonable agreement with the measurements using blood as working fluid. The extension of the Lucas-Washburn equation to non-Newtonian power-law fluids predicts well the velocity of the meniscus of the experiments using blood.
Collapse
Affiliation(s)
- Salvatore Cito
- Department of Mechanical Engineering, University Rovira i Virgili, Av. Països Catalans, 26, 43007 Tarragona, Spain; Department of Chemical Engineering, University Rovira i Virgili, Av. Països Catalans, 26, 43007 Tarragona, Spain
| | | | | | | | | | | | | |
Collapse
|
25
|
Forkert ND, Schmidt-Richberg A, Fiehler J, Illies T, Möller D, Handels H, Säring D. Automatic correction of gaps in cerebrovascular segmentations extracted from 3D time-of-flight MRA datasets. Methods Inf Med 2012; 51:415-22. [PMID: 22935785 DOI: 10.3414/me11-02-0037] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Accepted: 01/30/2012] [Indexed: 11/09/2022]
Abstract
OBJECTIVES Exact cerebrovascular segmentations are required for several applications in today's clinical routine. A major drawback of typical automatic segmentation methods is the occurrence of gaps within the segmentation. These gaps are typically located at small vessel structures exhibiting low intensities. Manual correction is very time-consuming and not suitable in clinical practice. This work presents a post-processing method for the automatic detection and closing of gaps in cerebrovascular segmentations. METHODS In this approach, the 3D centerline is calculated from an available vessel segmentation, which enables the detection of corresponding vessel endpoints. These endpoints are then used to detect possible connections to other 3D centerline voxels with a graph-based approach. After consistency check, reasonable detected paths are expanded to the vessel boundaries using a level set approach and combined with the initial segmentation. RESULTS For evaluation purposes, 100 gaps were artificially inserted at non-branching vessels and bifurcations in manual cerebrovascular segmentations derived from ten Time-of-Flight magnetic resonance angiography datasets. The results show that the presented method is capable of detecting 82% of the non-branching vessel gaps and 84% of the bifurcation gaps. The level set segmentation expands the detected connections with 0.42 mm accuracy compared to the initial segmentations. A further evaluation based on 10 real automatic segmentations from the same datasets shows that the proposed method detects 35 additional connections in average per dataset, whereas 92.7% were rated as correct by a medical expert. CONCLUSION The presented approach can considerably improve the accuracy of cerebrovascular segmentations and of following analysis outcomes.
Collapse
Affiliation(s)
- N D Forkert
- Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Bldg. W36, Martinistraße 52, 20246 Hamburg.
| | | | | | | | | | | | | |
Collapse
|
26
|
Li C, Wang S, Chen J, Yu H, Zhang Y, Jiang F, Mu S, Li H, Yang X. Influence of hemodynamics on recanalization of totally occluded intracranial aneurysms: a patient-specific computational fluid dynamic simulation study. J Neurosurg 2012; 117:276-83. [PMID: 22680247 DOI: 10.3171/2012.5.jns111558] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Some totally occluded intracranial aneurysms may recur. The role of hemodynamic mechanisms in this process remains to be elucidated. The authors used computational fluid dynamic analysis and investigated the local hemodynamic characteristics at the aneurysm neck before and after total embolization, attempting to identify hemodynamic risk factors leading to recurrence of totally embolized aneurysms.
Methods
Between May 2008 and June 2010, the authors recruited 17 consecutive patients with totally occluded intracranial aneurysms (7 recanalized and 10 stable lesions). Using patient-specific 3D digital subtraction angiography data, the hemodynamic features before and after embolization were retrospectively characterized.
Results
The overall preembolization blood flow patterns were nearly the same in the recanalized and stable groups, with no significant difference in either the maximum wall shear stress (WSS) (p = 0.914) or the spatially averaged WSS (p = 0.322) at peak systole at the aneurysm neck. After occlusion, the overall flow pattern changed, and the WSS distribution at the treated aneurysm neck differed in the 2 groups. In all of the 7 recanalized cases, both the maximum WSS and spatially averaged WSS at peak systole at the treated aneurysm neck were higher than those at the aneurysm neck before embolization. In contrast, both parameters were decreased in 70%–80% of the stable cases. After embolization, both the maximum WSS (p = 0.021) and spatially averaged WSS (p = 0.041) at peak systole at the treated aneurysm neck were higher in the recanalized group than in the stable group.
Conclusions
Higher WSS at the treated aneurysm neck after total embolization can be an important hemodynamic factor that contributes to aneurysm recurrence after endovascular treatment.
Collapse
Affiliation(s)
- Chuanhui Li
- 1Beijing Tiantan Hospital, Beijing Neurosurgical Institute, and
| | - Shengzhang Wang
- 3Department of Mechanics and Engineering Science, Fudan University, Shanghai; and
| | - Jialiang Chen
- 3Department of Mechanics and Engineering Science, Fudan University, Shanghai; and
| | - Hongyu Yu
- 2Department of Biomedical Engineering, Capital Medical University, Beijing
| | - Ying Zhang
- 1Beijing Tiantan Hospital, Beijing Neurosurgical Institute, and
| | - Fan Jiang
- 4Key Laboratory of Cardiovascular Remodeling and Function Research, Medical School and Qilu Hospital, Shandong University, Jinan, Shandong Province, China
| | - Shiqing Mu
- 1Beijing Tiantan Hospital, Beijing Neurosurgical Institute, and
| | - Haiyun Li
- 2Department of Biomedical Engineering, Capital Medical University, Beijing
| | - Xinjian Yang
- 1Beijing Tiantan Hospital, Beijing Neurosurgical Institute, and
| |
Collapse
|
27
|
Ugron Á, Szikora I, Paál G. Haemodynamic changes induced by intrasaccular packing on intracranial aneurysms: A computational fluid dynamic study. Interv Med Appl Sci 2012. [DOI: 10.1556/imas.4.2012.2.4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
Endovascular treatment of intracranial aneurysms is a routine medical practice. The most widely used technique is the packing the aneurysm sac with an embolic material. To gain deeper understanding in the effects of specific treatment methods, the intra-aneurysmal haemodynamics are studied with the help of patient-specific computational models. Numerical simulations demonstrated that embolisation with liquid polymer results in an overall decrease of the wall shear stress and pressure in the aneurysm region. Within the range of clinically relevant packing density, simulation of coil embolisation showed homogenisation and decrease of the wall loads on the aneurysm sac. Increasing the packing density above 20% produces little or no further reduction of intra-aneurysmal flow. Sufficient packing of the aneurysm sac results in significant intra-aneurysmal flow decrease associated with reduced wall loads but locally increased pressure or wall shear stress zones may appear depending on the specific vessel geometry.
Collapse
Affiliation(s)
- Ádám Ugron
- 1 Department of Hydrodynamic Systems, Budapest University of Technology and Economics, Budapest, Hungary
- 3 Budapest University of Technology and Economics, P.O. Box 91, H-1521, Budapest, Hungary
| | - István Szikora
- 2 National Institute of Neurosciences, Budapest, Hungary
| | - György Paál
- 1 Department of Hydrodynamic Systems, Budapest University of Technology and Economics, Budapest, Hungary
| |
Collapse
|
28
|
JOU LIANGDER, SALONER DAVID, HIGASHIDA RANDALL. DETERMINING INTRA-ANEURYSMAL FLOW FOR COILED CEREBRAL ANEURYSMS WITH DIGITAL FLUOROSCOPY. BIOMEDICAL ENGINEERING-APPLICATIONS BASIS COMMUNICATIONS 2012. [DOI: 10.4015/s1016237204000086] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Background and Purpose. Aneurysm geometry often dictates the success of coil embolization. A strong hemodynamic force or high intra-aneurysmal flow may indicate a high probability of recanalization. It is necessary to develop a tool that can predict and estimate the level of hemodynamic forces that coils are subject to during the procedure. Methods. A compartment model is developed to estimate the intra-aneurysmal flow after coil embolization from digital fluoroscopy. The model is based on the measured signal intensity curves for the aneurysm and adjacent artery and derives the amount of intra-aneurysmal flow reduction. A clinical case of a carotid aneurysm was used for demonstration of its ability. Results. Intra-aneurysmal flow was reduced by 70% after coil embolization, and the estimated porosity was 60%. Flow reduction was confirmed by computational fluid dynamics simulations that modeled the coiled aneurysm as a porous medium. Conclusion. Intra-aneurysmal flow reduction may be used to predict the outcome of coil embolization or possible aneurysm recurrence. A sustained high intra-aneurysmal flow prohibits complete embolization and allows recanalization of the aneurysm. The compartment model provides a reasonable estimate of intra-aneurysmal flow and hemodynamic forces on the coils.
Collapse
Affiliation(s)
- LIANG-DER JOU
- Department of Radiology, University of California San Francisco, USA
| | - DAVID SALONER
- Department of Radiology, University of California San Francisco, USA
| | - RANDALL HIGASHIDA
- Department of Radiology, University of California San Francisco, USA
| |
Collapse
|
29
|
NABAEI MALIKEH, FATOURAEE NASSER. COMPUTATIONAL MODELING OF FORMATION OF A CEREBRAL ANEURYSM UNDER THE INFLUENCE OF SMOOTH MUSCLE CELL RELAXATION. J MECH MED BIOL 2012. [DOI: 10.1142/s0219519411004599] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The mechanics of cerebral aneurysm pathogenesis, evolution and rupture are not yet well understood. This paper presents a numerical analysis of the formation of a saccular cerebral aneurysm in for the first time in a 3D model of the basilar artery bifurcation under normal and hypertensive blood pressure. Due to the excessive endothelium derived nitric oxide produced in high wall shear stress, we assumed that smooth muscle cell relaxation is the origin of the aneurysm formation. Arterial wall remodeling under constant tension was considered to be the other mechanism of disease evolution. The wall was constructed from two elastic and hyperelastic isotropic regions. The flow was considered steady, laminar, Newtonian, and incompressible. The fully coupled fluid and structure models were solved with the finite elements package ADINA 8.5. The wall shear stress, effective stress and deformation distributions under normal and hypertensive blood pressure were compared to a healthy bifurcation. The model shows that although the malfunction of the endothelial cell layer and the corresponding smooth muscle cell-related loss of vascular tone is important to the inception of the disease; A saccular aneurysm may not be formed by this mechanism alone, and also requires the fiber-related arterial wall remodeling for further development.
Collapse
Affiliation(s)
- MALIKEH NABAEI
- Student of Biomedical Engineering-Biomechanics, Amirkabir University of Technology, Biological Fluid Mechanics Research Laboratory, Tehran 15914, Iran
| | - NASSER FATOURAEE
- Faculty of Biomedical, Engineering, Amirkabir University of Technology, Biological Fluid Mechanics Research Laboratory, Tehran 15914, Iran
| |
Collapse
|
30
|
Hemodynamics of cerebral aneurysms: computational analyses of aneurysm progress and treatment. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2012; 2012:782801. [PMID: 22454695 PMCID: PMC3290806 DOI: 10.1155/2012/782801] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 11/10/2011] [Indexed: 12/02/2022]
Abstract
The progression of a cerebral aneurysm involves degenerative arterial wall remodeling. Various hemodynamic parameters are suspected to be major mechanical factors related to the genesis and progression of vascular diseases. Flow alterations caused by the insertion of coils and stents for interventional aneurysm treatment may affect the aneurysm embolization process. Therefore, knowledge of hemodynamic parameters may provide physicians with an advanced understanding of aneurysm progression and rupture, as well as the effectiveness of endovascular treatments. Progress in medical imaging and information technology has enabled the prediction of flow fields in the patient-specific blood vessels using computational analysis. In this paper, recent computational hemodynamic studies on cerebral aneurysm initiation, progress, and rupture are reviewed. State-of-the-art computational aneurysmal flow analyses after coiling and stenting are also summarized. We expect the computational analysis of hemodynamics in cerebral aneurysms to provide valuable information for planning and follow-up decisions for treatment.
Collapse
|
31
|
Spiegel M, Redel T, Zhang YJ, Struffert T, Hornegger J, Grossman RG, Doerfler A, Karmonik C. Tetrahedral vs. polyhedral mesh size evaluation on flow velocity and wall shear stress for cerebral hemodynamic simulation. Comput Methods Biomech Biomed Engin 2011; 14:9-22. [DOI: 10.1080/10255842.2010.518565] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
32
|
Luo B, Yang X, Wang S, Li H, Chen J, Yu H, Zhang Y, Zhang Y, Mu S, Liu Z, Ding G. High shear stress and flow velocity in partially occluded aneurysms prone to recanalization. Stroke 2011; 42:745-53. [PMID: 21233477 DOI: 10.1161/strokeaha.110.593517] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. However, the hemodynamic features in the residual neck of the partially embolized aneurysms and their influences on recanalization are rarely reported. In this study, we characterized the hemodynamics of partially occluded aneurysms, which were proven to undergo recanalization during follow-up using computational fluid dynamic analysis. METHODS From May 2007 to June 2009, we identified 11 partial aneurysms during follow-up, including 5 recanalized cases and 6 stable cases with 3-dimensional digital subtraction angiography. We retrospectively characterized the hemodynamic features around the residual aneurysmal pouch using the available postprocedural digital subtraction angiography image data. The occluded part of the aneurysm was regarded as completely separated from the circulation. RESULTS The overall blood flow patterns before embolization were almost the same in the recanalized and stable groups. After occlusion, the flow pattern changes, wall shear stress (WSS), and velocity at the remnant neck demonstrated different changes between the 2 groups. Specifically, in the recanalized group, high WSS regions were found near the neck in all 5 cases, with 4 of them being even higher than those before occlusion. Interestingly, in all cases, the high WSS area of the remnant neck coincided with the location where the aneurysm recanalization occurred. In the stable group, 5 out of 6 cases demonstrated lower WSS and velocity at the remnant neck after occlusion. CONCLUSIONS High WSS and blood flow velocity were consistently observed near the remnant neck of partially embolized aneurysms prone to future recanalization, suggesting that hemodynamic factors may have an important role in aneurysmal recurrence after endovascular treatment. The difference in flow pattern could be caused by the incomplete occlusion of the aneurysms.
Collapse
Affiliation(s)
- Bin Luo
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Tiantan Xili 6, Chongwen District, Beijing 100050, China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Schirmer CM, Malek AM. Critical Influence of Framing Coil Orientation on Intra-Aneurysmal and Neck Region Hemodynamics in a Sidewall Aneurysm Model. Neurosurgery 2010; 67:1692-702; discussion 1702. [DOI: 10.1227/neu.0b013e3181f9a93b] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
BACKGROUND:
Although coiling of intracranial aneurysms is thought to rely on obstruction of blood flow into the aneurysm and induction of intra-aneurysmal thrombosis, little data exist regarding the effect of coil deployment on hemodynamics.
OBJECTIVE:
To evaluate the effects of simulated coiling of a model aneurysm on flow and wall shear stress in the dome and neck regions using computational fluid dynamic analysis.
METHODS:
A spherical sidewall aneurysm on a curved parent vessel underwent simulated embolization with 1 or more computer-designed helical coils. The coils' axes had parallel, orthogonal, or transverse orientation with respect to blood flow. Pulsatile laminar flow computational fluid dynamic analysis was performed on high-resolution conformal meshes of the aneurysm-coil complex using realistic non-Newtonian blood viscosity.
RESULTS:
Intra-aneurysmal flow and energy flux into the dome were significantly reduced by coil insertion, with little effect on pressure distribution. Coiling increased viscosity in the distal dome with progressive spread toward the neck with greater coil packing. Coiling also decreased wall shear stress and its gradient both in the inflow zone and the downstream parent vessel. These alterations were dependent on coil orientation, with effectiveness rank order of parallel > transverse > orthogonal.
CONCLUSION:
We successfully modeled the hemodynamic effects of aneurysm coil embolization and uncovered a framing coil orientation dependence of dome and parent vessel hemodynamics. In addition to suggesting a pathophysiological link among coil configuration, protection from rupture, and aneurysm regrowth, these results pave the way for the analysis of aneurysm-coil complex interactions on a patient lesion-specific basis.
Collapse
Affiliation(s)
- Clemens M Schirmer
- Cerebrovascular and Endovascular Division, Department of Neurosurgery, Tufts Medical Center; and Tufts University School of Medicine, Boston, Massachusetts
| | - Adel M Malek
- Cerebrovascular and Endovascular Division, Department of Neurosurgery, Tufts Medical Center; and Tufts University School of Medicine, Boston, Massachusetts
| |
Collapse
|
34
|
Goubergrits L, Thamsen B, Berthe A, Poethke J, Kertzscher U, Affeld K, Petz C, Hege HC, Hoch H, Spuler A. In vitro study of near-wall flow in a cerebral aneurysm model with and without coils. AJNR Am J Neuroradiol 2010; 31:1521-8. [PMID: 20488901 DOI: 10.3174/ajnr.a2121] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Coil embolization procedures change the flow conditions in the cerebral aneurysm and, therefore, in the near-wall region. Knowledge of these flow changes may be helpful to optimize therapy. The goal of this study was to investigate the effect of the coil-packing attenuation on the near-wall flow and its variability due to differences in the coil structure. MATERIALS AND METHODS An enlarged transparent model of an ACA aneurysm was fabricated on the basis of CT angiography. The near-wall flow was visualized by using a recently proposed technique called Wall-PIV. Coil-packing attenuation of 10%, 15%, and 20% were investigated and compared with an aneurysmal flow without coils. Then the flow variability due to the coil introduction was analyzed in 10 experiments by using a packing attenuation of 15%. RESULTS A small packing attenuation of 10% already alters the near-wall flow significantly in a large part of the aneurysmal sac. These flow changes are characterized by a slow flow with short (interrupted) path lines. An increased packing attenuation expands the wall area exposed to the altered flow conditions. This area, however, depends on the coil position and/or on the 3D coil structure in the aneurysm. CONCLUSIONS To our knowledge, this is the first time the near-wall flow changes caused by coils in an aneurysm model have been visualized. It can be concluded that future hydrodynamic studies of coil therapy should include an investigation of the coil structure in addition to the coil-packing attenuation.
Collapse
Affiliation(s)
- L Goubergrits
- Biofluid Mechanics Laboratory Charité-Universitätsmedizin Berlin, Berlin, Germany.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Gunnarsson T, Tong FC, Klurfan P, Cawley CM, Dion JE. Angiographic and clinical outcomes in 200 consecutive patients with cerebral aneurysm treated with hydrogel-coated coils. AJNR Am J Neuroradiol 2009; 30:1657-64. [PMID: 19696140 DOI: 10.3174/ajnr.a1691] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Denser coil packing in intracranial aneurysms is believed to result in lower recanalization rates. Hydrogel-coated expandable coils (HydroCoil) improve volumetric packing of aneurysms in animal models and clinical studies, but data from large clinical series are limited. The objective of this retrospective analysis was to analyze immediate and follow-up angiographic results as well as complications in a large consecutive series of patients treated with HydroCoils at a single institution. MATERIALS AND METHODS Retrospective analysis was performed of periprocedural complications, immediate and follow-up angiograms, and retreatments of the first 200 consecutive intracranial aneurysms treated at Emory University Hospital. RESULTS One hundred eighty-seven patients with 200 intracranial aneurysms were treated with HydroCoils during a 3-year period. Immediate angiograms showed complete aneurysmal obliteration in 58.4% of small aneurysms and 42.7% of large aneurysms. Periprocedural complications included early rebleeding and thromboembolic events resulting in permanent neurologic morbidity and mortality in 6% of cases. Follow-up angiography during an average of 16.3 months demonstrated recanalization in 17.7% of small aneurysms and 28.6% of large aneurysms, requiring retreatment in 6.3% and 19.0% of cases, respectively. During the same time period, there was delayed angiographic improvement in aneurysm obliteration in 26.6% of small aneurysms and 26.2% of large aneurysms. CONCLUSIONS First-generation HydroCoil treatment of intracranial aneurysms has a favorable rate of recanalization compared with most large series of pure platinum coils with similar complication rates.
Collapse
Affiliation(s)
- T Gunnarsson
- Division of Neurosurgery, McMaster University Hospital, Hamilton, Ontario, Canada
| | | | | | | | | |
Collapse
|
36
|
Ventikos Y, Holland EC, Bowker TJ, Watton PN, Kakalis NMP, Megahed M, Zhu F, Summers PE, Byrne JV. Computational modelling for cerebral aneurysms: risk evaluation and interventional planning. Br J Radiol 2009; 82 Spec No 1:S62-71. [DOI: 10.1259/bjr/14303482] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
|
37
|
Abstract
The initiation and progression of cerebral aneurysms are degenerative processes of the arterial wall driven by a complex interaction of biological and hemodynamic factors. Endothelial cells on the artery wall respond physiologically to blood-flow patterns. In normal conditions, these responses are associated with nonpathological tissue remodeling and adaptation. The combination of abnormal blood patterns and genetics predisposition could lead to the pathological formation of aneurysms. Here, we review recent progress on the basic mechanisms of aneurysm formation and evolution, with a focus on the role of hemodynamic patterns.
Collapse
Affiliation(s)
- Daniel M. Sforza
- Center for Computational Fluid Dynamics, George Mason University, Fairfax, Virginia 22030
| | - Christopher M. Putman
- Interventional Neuroradiology, Inova Fairfax Hospital, Falls Church, Virginia 22042
- Department of Neurosurgery, School of Medicine, George Washington University, Washington, DC 20037
| | - Juan Raul Cebral
- Center for Computational Fluid Dynamics, George Mason University, Fairfax, Virginia 22030
| |
Collapse
|
38
|
Wei Y, Cotin S, Fang L, Allard J, Pan C, Ma S. Toward Real-Time Simulation of Blood-Coil Interaction during Aneurysm Embolization. MEDICAL IMAGE COMPUTING AND COMPUTER-ASSISTED INTERVENTION – MICCAI 2009 2009; 12:198-205. [DOI: 10.1007/978-3-642-04268-3_25] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
|
39
|
Ortega J, Hartman J, Rodriguez J, Maitland D. Post-treatment hemodynamics of a basilar aneurysm and bifurcation. Ann Biomed Eng 2008; 36:1531-46. [PMID: 18629647 PMCID: PMC2704058 DOI: 10.1007/s10439-008-9535-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Accepted: 06/30/2008] [Indexed: 11/29/2022]
Abstract
To investigate whether or not a successful aneurysm treatment procedure can subject a parent artery to harmful hemodynamic stresses, computational fluid dynamics simulations are performed on a patient-specific basilar aneurysm and bifurcation before and after a virtual endovascular treatment. Prior to treatment, the aneurysm at systole is filled with a periodic train of vortex tubes, which form at the aneurysm neck and advect upwards into the dome. Following the treatment procedure however, the motion of the vortex train is inhibited by the aneurysm filling material, which confines the vortex tubes to the region beneath the aneurysm neck. Analysis of the post-treatment flow field indicates that the impingement of the basilar artery flow upon the treated aneurysm neck and the close proximity of a vortex tube to the parent artery wall increase the maximum wall shear stresses to values approximately equal to 50 Pa at systole. Calculation of the time-averaged wall shear stresses indicates that there is a 1.4 x 10(-7) m(2) area on the parent artery exposed to wall shear stresses greater than 37.9 Pa, a value shown by Fry [Circ. Res. 22(2):165-197, 1968] to cause severe damage to the endothelial cells that line the artery wall. The results of this study demonstrate that it is possible for a treatment procedure, which successfully isolates the aneurysm from the circulation and leaves no aneurysm neck remnant, to elevate the hemodynamic stresses to levels that are injurious to the artery wall.
Collapse
Affiliation(s)
- J Ortega
- Lawrence Livermore National Laboratory, P.O. Box 808, L-645, Livermore, CA 94550, USA.
| | | | | | | |
Collapse
|
40
|
Ford MD, Nikolov HN, Milner JS, Lownie SP, Demont EM, Kalata W, Loth F, Holdsworth DW, Steinman DA. PIV-measured versus CFD-predicted flow dynamics in anatomically realistic cerebral aneurysm models. J Biomech Eng 2008; 130:021015. [PMID: 18412502 DOI: 10.1115/1.2900724] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Computational fluid dynamics (CFD) modeling of nominally patient-specific cerebral aneurysms is increasingly being used as a research tool to further understand the development, prognosis, and treatment of brain aneurysms. We have previously developed virtual angiography to indirectly validate CFD-predicted gross flow dynamics against the routinely acquired digital subtraction angiograms. Toward a more direct validation, here we compare detailed, CFD-predicted velocity fields against those measured using particle imaging velocimetry (PIV). Two anatomically realistic flow-through phantoms, one a giant internal carotid artery (ICA) aneurysm and the other a basilar artery (BA) tip aneurysm, were constructed of a clear silicone elastomer. The phantoms were placed within a computer-controlled flow loop, programed with representative flow rate waveforms. PIV images were collected on several anterior-posterior (AP) and lateral (LAT) planes. CFD simulations were then carried out using a well-validated, in-house solver, based on micro-CT reconstructions of the geometries of the flow-through phantoms and inlet/outlet boundary conditions derived from flow rates measured during the PIV experiments. PIV and CFD results from the central AP plane of the ICA aneurysm showed a large stable vortex throughout the cardiac cycle. Complex vortex dynamics, captured by PIV and CFD, persisted throughout the cardiac cycle on the central LAT plane. Velocity vector fields showed good overall agreement. For the BA, aneurysm agreement was more compelling, with both PIV and CFD similarly resolving the dynamics of counter-rotating vortices on both AP and LAT planes. Despite the imposition of periodic flow boundary conditions for the CFD simulations, cycle-to-cycle fluctuations were evident in the BA aneurysm simulations, which agreed well, in terms of both amplitudes and spatial distributions, with cycle-to-cycle fluctuations measured by PIV in the same geometry. The overall good agreement between PIV and CFD suggests that CFD can reliably predict the details of the intra-aneurysmal flow dynamics observed in anatomically realistic in vitro models. Nevertheless, given the various modeling assumptions, this does not prove that they are mimicking the actual in vivo hemodynamics, and so validations against in vivo data are encouraged whenever possible.
Collapse
Affiliation(s)
- Matthew D Ford
- Imaging Research Laboratories, Robarts Research Institute, London, Canada N6A 5K8
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Kakalis NMP, Mitsos AP, Byrne JV, Ventikos Y. The haemodynamics of endovascular aneurysm treatment: a computational modelling approach for estimating the influence of multiple coil deployment. IEEE TRANSACTIONS ON MEDICAL IMAGING 2008; 27:814-824. [PMID: 18541488 DOI: 10.1109/tmi.2008.915549] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This paper proposes a novel computational methodology for modelling the haemodynamic effects of endovascular coil embolization for cerebral aneurysms. We employ high-resolution 3-D angiographic data to reconstruct the intracranial geometry and we model the coiled part of the aneurysm as a porous medium, with porosity decreasing as coils are inserted. The actual dimensions of the coils employed are used to determine the characteristics of the porous medium. Simulation results for saccular aneurysms from the anterior communicating and middle cerebral arteries show that insertion of coils rapidly changes intraaneurysmal blood flow and causes reduction in mural pressure and blood velocity up to stagnation, providing favorable conditions for thrombus formation and obliteration of the aneurysm.
Collapse
Affiliation(s)
- Nikolaos M P Kakalis
- Department of Engineering Science and the Institute of Biomedical Engineering, University of Oxford, Oxford OX1 3PJ, UK
| | | | | | | |
Collapse
|
42
|
Haemodynamic simulation of aneurysm coiling in an anatomically accurate computational fluid dynamics model: technical note. Neuroradiology 2007; 50:341-7. [DOI: 10.1007/s00234-007-0334-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Accepted: 10/17/2007] [Indexed: 11/26/2022]
|
43
|
Ortega J, Maitland D, Wilson T, Tsai W, Savaş O, Saloner D. Vascular Dynamics of a Shape Memory Polymer Foam Aneurysm Treatment Technique. Ann Biomed Eng 2007; 35:1870-84. [PMID: 17676399 DOI: 10.1007/s10439-007-9358-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Accepted: 07/12/2007] [Indexed: 10/23/2022]
Abstract
The vascular dynamics of a shape memory polymer foam aneurysm treatment technique are assessed through the simulated treatment of a generic basilar aneurysm using coupled fluid dynamics and heat transfer calculations. The shape memory polymer foam, which expands to fill the aneurysm when heated, is modeled at three discrete stages of the treatment procedure. To estimate an upper bound for the maximum amount of thermal damage due to foam heating, a steady velocity is specified through the basilar artery, corresponding to a minimum physiological flow velocity over a cardiac cycle. During expansion, the foam alters the flow patterns within the aneurysm by shielding the aneurysm dome from a confined jet that issues from the basilar artery. The time scales for thermal damage to the artery walls and surrounding blood flow are computed from the temperature field. The flow through the post-treatment bifurcation is comprised of two counter-rotating vortex tubes that are located beneath the aneurysm neck and extend downstream into the outlet arteries. Beneath the aneurysm neck, a marked increase in the wall shear stress is observed due to the close proximity of the counter-rotating vortex tubes to the artery wall.
Collapse
Affiliation(s)
- Jason Ortega
- Engineering, Lawrence Livermore National Laboratory, P.O. Box 808, L-644, Livermore, CA 94551, USA.
| | | | | | | | | | | |
Collapse
|
44
|
Gunnarsson T, Klurfan P, terBrugge KG, Willinsky RA. Treatment of intracranial aneurysms with hydrogel coated expandable coils. Can J Neurol Sci 2007; 34:38-46. [PMID: 17352345 DOI: 10.1017/s0317167100018710] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Coiling of intracranial aneurysms with platinum coils sometimes results in relatively poor angiographic results which may be is related to low packing volumes achieved. Hydrogel coated expandable coils (HydroCoil) have been shown to achieve better aneurysm volume filling which may potentially result in lower recanalization rates. Currently there is limited clinical data on their safety and efficacy in aneurysm treatment. METHODS We analyzed data from a prospectively collected database on patients treated at the Toronto Western Hospital. The analysis included the patients' characteristics, aneurysm size, packing, procedure related complications, recanalization and clinical outcome. RESULTS Twenty-nine aneurysms were treated with HydroCoils only or in combination with other coils. The average calculated filling of the aneurysm volume was 74-76%. On the immediate post treatment angiograms, 44% of the berry type aneurysms were completely obliterated, 33% had a residual neck and, in 20%, a residual aneurysm was seen. Follow-up imaging was available in 23 cases. On imaging follow-up (from 2 days to 11 months) one dissecting aneurysm had recanalized. There were six technical/medical complications with no clinical consequences. Two clinically significant procedural related complications occurred. CONCLUSIONS HydroCoils can be used effectively to treat intracranial aneurysms. The volume expansion allows for much greater packing than described for bare platinum coils, which may result in better long-term results. The recanalization rate is low but the limited follow-up does not allow for any conclusion regarding the long-term outcome. The complication rate is similar to larger current series using bare platinum coils.
Collapse
Affiliation(s)
- Thorsteinn Gunnarsson
- Division of Neuroradiology, Toronto Western Hospital, University of Toronto, Ontario, Canada
| | | | | | | |
Collapse
|
45
|
Cha KS, Balaras E, Lieber BB, Sadasivan C, Wakhloo AK. Modeling the Interaction of Coils With the Local Blood Flow After Coil Embolization of Intracranial Aneurysms. J Biomech Eng 2007; 129:873-79. [DOI: 10.1115/1.2800773] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
46
|
Sherif C, Plenk H, Grossschmidt K, Kanz F, Bavinzski G. Computer-assisted quantification of occlusion and coil densities on angiographic and histological images of experimental aneurysms. Neurosurgery 2006; 58:559-66; discussion 559-66. [PMID: 16528198 DOI: 10.1227/01.neu.0000197490.60670.a8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Occlusion rates (OR) and coil densities were quantified by computer-assisted morphometry on angiograms and histological ground sections of coil-embolized experimental aneurysms. The aims of this study were 1) to develop computer-assisted evaluations of angiographic OR and histometrical OR, 2) to compare these results to subjectively estimated angiographic OR from clinical practice, and 3) to test the correlation between histometrical data of coil density and occlusion. METHODS Eight rabbit carotid-bifurcation aneurysms had been followed by digital subtraction angiography (DSA) before and after Guglielmi detachable coil embolization and at sacrifice (1 h to 24 wk postembolization). Angiographic OR was subjectively estimated, then determined by computer-assisted density-gradient distinction on digitized DSAs. Histometrically, maximum length, neck width, total area, recanalized area, and coil-occupied area were measured on digitized and calibrated color micrographs from surface-stained histological ground sections of the aneurysms. Histometrical OR and coil density were calculated as indirect parameters. RESULTS Subjective versus computer-assisted angiographic OR yielded for one aneurysm, 100% versus 100%, and for three aneurysms less than 90% versus 65 to 60% occlusion. For four aneurysms, OR was estimated greater than 90%, whereas computer-assisted OR ranged between 45 to 80%, the latter being more precise because of better definition of the aneurysm's total area on digitized DSA. Histometrical OR ranged between 32.8 and 87.6%, but did not correlate significantly with computer-assisted angiographic OR (r = 0.467, P > 0.1) because of differences in two aneurysms. Coil densities between 5.5 and 22.1% were slightly lower than reported in literature but significantly correlated to histometrical OR (r = 0.646, P < 0.05). CONCLUSION Computer-assisted DSA evaluation, delivering more precise values than subjectively estimated occlusion, may be a useful tool for follow-up studies. Comparing computer-assisted angiographic with histometrical occlusion demonstrates limits of DSA in displaying the real morphology of coil-embolized aneurysms. The clinically postulated correlation of OR and coil densities was statistically corroborated.
Collapse
Affiliation(s)
- Camillo Sherif
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | | | | | | | | |
Collapse
|
47
|
Karmonik C, Benndorf G, Klucznik R, Haykal H, Strother CM. Wall shear stress variations in basilar tip aneurysms investigated with computational fluid dynamics. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2006; 2006:3214-3217. [PMID: 17946165 DOI: 10.1109/iembs.2006.259689] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Hemodynamics are thought to play an important role in the creation, thrombosis, recanalization, regrowth and re-bleeding of cerebral aneurysms treated by endovascular means. However, their exact role and interaction is unclear and warrants further study. Towards a systematic classification of the hemodynamics in intracranial aneurysms, we investigated the dependence of the values of the magnitude of the wall shear stresses in the vicinity of the aneurysm on varying inflow conditions in three basilar tip aneurysms.
Collapse
|
48
|
Kobayashi N, Miyachi S, Okamoto T, Kojima T, Hattori K, Qian S, Takeda H, Yoshida J. Computer simulation of flow dynamics in paraclinoidal aneurysms. Interv Neuroradiol 2005; 11:197-203. [PMID: 20584475 DOI: 10.1177/159101990501100301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Accepted: 08/25/2005] [Indexed: 11/17/2022] Open
Abstract
SUMMARY Endovascular treatment, which is very useful method especially for paraclinoidal aneurysms, has the limitations of coil compaction and recanalization, which are difficult to predict. We tried to understand flow dynamic features, one of the important factors of such problems, using computer flow dynamics (CFD) simulations. CFD simulations were made in paraclinoidal aneurysm model of different size and protruded directions. Flow patterns, flow velocities and pressure are analyzed. Although the pressure on the aneurismal orifice is highest in the aneurysm protruding vertically - upward, the flow velocity is highest in the superior-medial protruding one. Significant difference is not observed in either flow patterns, flow velocities or pressures on the aneurismal orifices between the sizes of aneurismal sac. Among paraclinoidal aneurysms, an aneurysm protruding to superior-medially receives the most severe haemodynamic stresses at the orifice and the aneurysm size does not cause significant differences in the aspect of flow dynamics. It should be considered in the treatment of such aneurysms.
Collapse
Affiliation(s)
- N Kobayashi
- Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya; Japan -
| | | | | | | | | | | | | | | |
Collapse
|
49
|
Narracott A, Smith S, Lawford P, Liu H, Himeno R, Wilkinson I, Griffiths P, Hose R. Development and validation of models for the investigation of blood clotting in idealized stenoses and cerebral aneurysms. J Artif Organs 2005; 8:56-62. [PMID: 15951982 DOI: 10.1007/s10047-004-0274-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Accepted: 10/12/2004] [Indexed: 10/25/2022]
Abstract
An in vitro model of blood clotting is presented using hypercoaguable milk as an analog for blood. Milk clot formation was studied for periods of 2, 5, 10, 20, and 30 min within an idealized stenosis geometry. Clot formation was recorded using photography, clot casting, and clot mass calculation. The distribution of clot within the fluid was seen to be in good agreement with a previous study that used a residence time model to predict areas of clot formation in thrombin solution. A numerical model was formulated within computational fluid dynamics package CFX that allowed local activation of blood clotting to be simulated. This model was applied to the analysis of an idealized cerebral aneurysm geometry. An idealized coil geometry was included within the aneurysm and clotting fluid concentration and fluid residence time were modeled using transport equations within CFX. The viscosity of the fluid was defined as a function of both residence time and clotting fluid concentration. The model was seen to produce features consistent with observations of thrombosis within cerebral aneurysms, while avoiding the unrealistic build up of clot in near-wall regions that is associated with a pure residence time model.
Collapse
Affiliation(s)
- Andrew Narracott
- Division of Clinical Sciences (South), Department of Medical Physics and Clinical Engineering, University of Sheffield, Sheffield, UK.
| | | | | | | | | | | | | | | |
Collapse
|
50
|
Cebral JR, Löhner R. Efficient simulation of blood flow past complex endovascular devices using an adaptive embedding technique. IEEE TRANSACTIONS ON MEDICAL IMAGING 2005; 24:468-476. [PMID: 15822805 DOI: 10.1109/tmi.2005.844172] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The simulation of blood flow past endovascular devices such as coils and stents is a challenging problem due to the complex geometry of the devices. Traditional unstructured grid computational fluid dynamics relies on the generation of finite element grids that conform to the boundary of the computational domain. However, the generation of such grids for patient-specific modeling of cerebral aneurysm treatment with coils or stents is extremely difficult and time consuming. This paper describes the application of an adaptive grid embedding technique previously developed for complex fluid structure interaction problems to the simulation of endovascular devices. A hybrid approach is used: the vessel walls are treated with body conforming grids and the endovascular devices with an adaptive mesh embedding technique. This methodology fits naturally in the framework of image-based computational fluid dynamics and opens the door for exploration of different therapeutic options and personalization of endovascular procedures.
Collapse
Affiliation(s)
- Juan R Cebral
- School of Computational Sciences, George Mason University, 4400 University Drive, MSN 4C7, Fairfax, VA 22030, USA.
| | | |
Collapse
|