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Su T, Reymond P, Brina O, Bouillot P, Machi P, Delattre BMA, Jin L, Lövblad KO, Vargas MI. Large Neck and Strong Ostium Inflow as the Potential Causes for Delayed Occlusion of Unruptured Sidewall Intracranial Aneurysms Treated by Flow Diverter. AJNR Am J Neuroradiol 2020; 41:488-494. [PMID: 32054620 DOI: 10.3174/ajnr.a6413] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 12/23/2019] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Flow diverter-induced hemodynamic change plays an important role in the mechanism of intracranial aneurysm occlusion. Our aim was to explore the relationship between aneurysm features and flow-diverter treatment of unruptured sidewall intracranial aneurysms. MATERIALS AND METHODS MR imaging, 4D phase-contrast, was prospectively performed before flow diverter implantation in each patient with unruptured intracranial aneurysm. Two postprocedure follow-ups were scheduled at 6 and 12 months. Responses were grouped according to whether the aneurysms were occluded or remnant. Preprocedural aneurysm geometries and ostium hemodynamics in 38 patients were compared between the 2 groups at 6 and 12 months. Receiver operating characteristic curve analyses were performed for significant geometric and hemodynamic continuous parameters. RESULTS After the 6-month assessment, 21 of 41 intracranial aneurysms were occluded, and 9 additional aneurysms were occluded at 12 months. Geometrically, the ostium maximum diameter was significantly larger in the remnant group at 6 and 12 months (both P < .001). Hemodynamically, the proximal inflow zone was more frequently observed in the remnant group at 6 months. Several preprocedural ostium hemodynamic parameters were significantly higher in the remnant group. As a prediction for occlusion, the areas under the curve of the ostium maximum diameter (for 6 and 12 months), systolic inflow rate ratio (for 6 months), and systolic inflow area (for 12 months) reached 0.843, 0.883, 0.855, and 0.860, respectively. CONCLUSIONS Intracranial aneurysms with a large ostium and strong ostium inflow may need a longer time for occlusion. Preprocedural 4D flow MR imaging can well illustrate ostium hemodynamics and characterize aneurysm treatment responses.
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Affiliation(s)
- T Su
- From the Department of Interventional Radiology (T.S., L.J.), Beijing Friendship Hospital, Capital Medical University, Beijing, People's Republic of China
| | - P Reymond
- Division of Neuroradiology and Neuro-Interventional Radiology (P.R., O.B., P.M., K.O.L., M.I.V.)
| | - O Brina
- Division of Neuroradiology and Neuro-Interventional Radiology (P.R., O.B., P.M., K.O.L., M.I.V.)
| | - P Bouillot
- and Division of Radiology (B.M.A.D.), University Hospitals of Geneva, Geneva, Switzerland
| | - P Machi
- Division of Neuroradiology and Neuro-Interventional Radiology (P.R., O.B., P.M., K.O.L., M.I.V.)
| | - B M A Delattre
- Department of Quantum Matter Physics (P.B.), University of Geneva, Geneva, Switzerland
| | - L Jin
- From the Department of Interventional Radiology (T.S., L.J.), Beijing Friendship Hospital, Capital Medical University, Beijing, People's Republic of China
| | - K O Lövblad
- Division of Neuroradiology and Neuro-Interventional Radiology (P.R., O.B., P.M., K.O.L., M.I.V.)
| | - M I Vargas
- Division of Neuroradiology and Neuro-Interventional Radiology (P.R., O.B., P.M., K.O.L., M.I.V.)
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Brina O, Bouillot P, Reymond P, Luthman AS, Santarosa C, Fahrat M, Lovblad KO, Machi P, Delattre BMA, Pereira VM, Vargas MI. How Flow Reduction Influences the Intracranial Aneurysm Occlusion: A Prospective 4D Phase-Contrast MRI Study. AJNR Am J Neuroradiol 2019; 40:2117-2123. [PMID: 31727755 DOI: 10.3174/ajnr.a6312] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/20/2019] [Indexed: 12/28/2022]
Abstract
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 ± 7.1 cm/s before to 7.2 ± 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.
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Affiliation(s)
- O Brina
- From the Divisions of Neuroradiology (O.B., P.R., A.S.L., C.S., K.O.L., P.M., V.M.P., M.I.V.)
| | - P Bouillot
- Department of Quantum Matter Physics (P.B.), University of Geneva, Geneva, Switzerland
| | - P Reymond
- From the Divisions of Neuroradiology (O.B., P.R., A.S.L., C.S., K.O.L., P.M., V.M.P., M.I.V.)
| | - A S Luthman
- From the Divisions of Neuroradiology (O.B., P.R., A.S.L., C.S., K.O.L., P.M., V.M.P., M.I.V.)
| | - C Santarosa
- From the Divisions of Neuroradiology (O.B., P.R., A.S.L., C.S., K.O.L., P.M., V.M.P., M.I.V.)
| | - M Fahrat
- Laboratory for Hydraulic Machines (M.F.), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - K O Lovblad
- From the Divisions of Neuroradiology (O.B., P.R., A.S.L., C.S., K.O.L., P.M., V.M.P., M.I.V.)
| | - P Machi
- From the Divisions of Neuroradiology (O.B., P.R., A.S.L., C.S., K.O.L., P.M., V.M.P., M.I.V.)
| | - B M A Delattre
- Radiology (B.M.A.D.), Geneva University Hospitals, University of Geneva, Geneva, Switzerland
| | - V M Pereira
- From the Divisions of Neuroradiology (O.B., P.R., A.S.L., C.S., K.O.L., P.M., V.M.P., M.I.V.).,Division of Neuroradiology (V.M.P.).,Department of Medical Imaging (V.M.P.).,Division of Neurosurgery (V.M.P.), Department of Surgery, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - M I Vargas
- From the Divisions of Neuroradiology (O.B., P.R., A.S.L., C.S., K.O.L., P.M., V.M.P., M.I.V.)
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Chnafa C, Bouillot P, Brina O, Najafi M, Delattre B, Vargas M, Pereira V, Steinman D. Errors in power-law estimations of inflow rates for intracranial aneurysm CFD. J Biomech 2018; 80:159-165. [DOI: 10.1016/j.jbiomech.2018.09.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 08/02/2018] [Accepted: 09/04/2018] [Indexed: 11/28/2022]
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Chnafa C, Brina O, Pereira VM, Steinman DA. Better Than Nothing: A Rational Approach for Minimizing the Impact of Outflow Strategy on Cerebrovascular Simulations. AJNR Am J Neuroradiol 2018; 39:337-343. [PMID: 29269407 DOI: 10.3174/ajnr.a5484] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 10/13/2017] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Computational fluid dynamics simulations of neurovascular diseases are impacted by various modeling assumptions and uncertainties, including outlet boundary conditions. Many studies of intracranial aneurysms, for example, assume zero pressure at all outlets, often the default ("do-nothing") strategy, with no physiological basis. Others divide outflow according to the outlet diameters cubed, nominally based on the more physiological Murray's law but still susceptible to subjective choices about the segmented model extent. Here we demonstrate the limitations and impact of these outflow strategies, against a novel "splitting" method introduced here. MATERIALS AND METHODS With our method, the segmented lumen is split into its constituent bifurcations, where flow divisions are estimated locally using a power law. Together these provide the global outflow rate boundary conditions. The impact of outflow strategy on flow rates was tested for 70 cases of MCA aneurysm with 0D simulations. The impact on hemodynamic indices used for rupture status assessment was tested for 10 cases with 3D simulations. RESULTS Differences in flow rates among the various strategies were up to 70%, with a non-negligible impact on average and oscillatory wall shear stresses in some cases. Murray-law and splitting methods gave flow rates closest to physiological values reported in the literature; however, only the splitting method was insensitive to arbitrary truncation of the model extent. CONCLUSIONS Cerebrovascular simulations can depend strongly on the outflow strategy. The default zero-pressure method should be avoided in favor of Murray-law or splitting methods, the latter being released as an open-source tool to encourage the standardization of outflow strategies.
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Affiliation(s)
- C Chnafa
- From the Biomedical Simulation Laboratory (C.C., D.A.S.), Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - O Brina
- Joint Division of Medical Imaging (O.B., V.M.P.), Department of Medical Imaging and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, and University of Toronto, Toronto, Ontario, Canada
| | - V M Pereira
- Joint Division of Medical Imaging (O.B., V.M.P.), Department of Medical Imaging and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, and University of Toronto, Toronto, Ontario, Canada
| | - D A Steinman
- From the Biomedical Simulation Laboratory (C.C., D.A.S.), Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
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Chnafa C, Bouillot P, Brina O, Delattre BMA, Vargas MI, Lovblad KO, Pereira VM, Steinman DA. Vessel calibre and flow splitting relationships at the internal carotid artery terminal bifurcation. Physiol Meas 2017; 38:2044-2057. [DOI: 10.1088/1361-6579/aa92bf] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Chnafa C, Valen-Sendstad K, Brina O, Pereira V, Steinman D. Improved reduced-order modelling of cerebrovascular flow distribution by accounting for arterial bifurcation pressure drops. J Biomech 2017; 51:83-88. [DOI: 10.1016/j.jbiomech.2016.12.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 11/04/2016] [Accepted: 12/03/2016] [Indexed: 01/25/2023]
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Morales HG, Bonnefous O, Geers AJ, Brina O, Pereira VM, Spelle L, Moret J, Larrabide I. Does Arterial Flow Rate Affect the Assessment of Flow-Diverter Stent Performance? AJNR Am J Neuroradiol 2016; 37:2293-2298. [PMID: 27633810 DOI: 10.3174/ajnr.a4933] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 07/20/2016] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Our aim was to assess the performance of flow-diverter stents. The pre- and end-of-treatment angiographies are commonly compared. However, the arterial flow rate may change between acquisitions; therefore, a better understanding of its influence on the local intra-aneurysmal hemodynamics before and after flow-diverter stent use is required. MATERIALS AND METHODS Twenty-five image-based aneurysm models extracted from 3D rotational angiograms were conditioned for computational fluid dynamics simulations. Pulsatile simulations were performed at different arterial flow rates, covering a wide possible range of physiologic flows among 1-5 mL/s. The effect of flow-diverter stents on intra-aneurysmal hemodynamics was numerically simulated with a porous medium model. Spatiotemporal-averaged intra-aneurysmal flow velocity and flow rate were calculated for each case to quantify the hemodynamics after treatment. The short-term flow-diverter stent performance was characterized by the relative velocity reduction inside the aneurysm. RESULTS Spatiotemporal-averaged intra-aneurysmal flow velocity before and after flow-diverter stent use is linearly proportional to the mean arterial flow rate (minimum R2 > 0.983 of the linear regression models for untreated and stented models). Relative velocity reduction asymptotically decreases with increasing mean arterial flow rate. When the most probable range of arterial flow rate was considered (3-5 mL/s), instead of the wide possible flow range, the mean SD of relative velocity reduction was reduced from 3.6% to 0.48%. CONCLUSIONS Both intra-aneurysmal aneurysm velocity and flow-diverter stent performance depend on the arterial flow rate. The performance could be considered independent of the arterial flow rates within the most probable range of physiologic flows.
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Affiliation(s)
- H G Morales
- From Medisys-Philips Research (H.G.M., O.Bonnefous), Paris, France
| | - O Bonnefous
- From Medisys-Philips Research (H.G.M., O.Bonnefous), Paris, France
| | - A J Geers
- Centre for Cardiovascular Science (A.J.G.), University of Edinburgh, Edinburgh, Scotland.,Department of Information and Communication Technologies (A.J.G.), Universitat Pompeu Fabra, Barcelona, Spain
| | - O Brina
- Department of Information Neuroradiology (O.Brina), University Hospital of Geneva, Geneva, Switzerland
| | - V M Pereira
- Department of Medical Imaging and Department of Surgery (V.M.P.), University Health Network, Toronto, Ontario, Canada
| | - L Spelle
- Interventional Neuroradiology (L.S., J.M.), Beaujon University Hospital, Clichy, France.,Paris Diderot University (L.S.), Paris, France
| | - J Moret
- Interventional Neuroradiology (L.S., J.M.), Beaujon University Hospital, Clichy, France
| | - I Larrabide
- PLADEMA-CONICET (I.L.), Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina
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Mendes Pereira V, Brina O, Bracken J, Krings T, Lovblad K, van Nijnatten F, Ruijters D, Grünhagen T. E-081 Assessment of the MAFA Ratio as a Quantitative Prognostic Marker of Aneurysm Occlusion after Flow Diverter Treatment. J Neurointerv Surg 2016. [DOI: 10.1136/neurintsurg-2016-012589.153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Bouillot P, Brina O, Yilmaz H, Farhat M, Erceg G, Lovblad KO, Vargas MI, Kulcsar Z, Pereira VM. Virtual-versus-Real Implantation of Flow Diverters: Clinical Potential and Influence of Vascular Geometry. AJNR Am J Neuroradiol 2016; 37:2079-2086. [PMID: 27365325 DOI: 10.3174/ajnr.a4845] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/24/2016] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Intracranial stents have become extremely important in the endovascular management of complex intracranial aneurysms. Sizing and landing zone predictions are still very challenging steps in the procedure. Virtual stent deployment may help therapeutic planning, device choice, and hemodynamic simulations. We aimed to assess the predictability of our recently developed virtual deployment model by comparing in vivo and virtual stents implanted in a consecutive series of patients presenting with intracranial aneurysms. MATERIALS AND METHODS Virtual stents were implanted in patient-specific geometries of intracranial aneurysms treated with the Pipeline Embolization Device. The length and cross-section of virtual and real stents measured with conebeam CT were compared. The influence of vessel geometry modifications occurring during the intervention was analyzed. RESULTS The virtual deployment based on pre- and poststent implantation 3D rotational angiography overestimated (underestimated) the device length by 13% ± 11% (-9% ± 5%). These differences were highly correlated (R2 = 0.67) with the virtual-versus-real stent radius differences of -6% ± 7% (5% ± 4%) for predictions based on pre- and poststent implantation 3D rotational angiography. These mismatches were due principally to implantation concerns and vessel-shape modifications. CONCLUSIONS The recently proposed geometric model was shown to predict accurately the deployment of Pipeline Embolization Devices when the stent radius was well-assessed. However, unpredictable delivery manipulations and variations of vessel geometry occurring during the intervention might impact the stent implantation.
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Affiliation(s)
- P Bouillot
- From the Division of Neuroradiology (P.B., O.B., H.Y., G.E., K.-O.L., M.I.V., Z.K.), University Hospitals of Geneva, Geneva, Switzerland.,Laboratory for Hydraulic Machines (P.B., M.F.), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - O Brina
- From the Division of Neuroradiology (P.B., O.B., H.Y., G.E., K.-O.L., M.I.V., Z.K.), University Hospitals of Geneva, Geneva, Switzerland
| | - H Yilmaz
- From the Division of Neuroradiology (P.B., O.B., H.Y., G.E., K.-O.L., M.I.V., Z.K.), University Hospitals of Geneva, Geneva, Switzerland
| | - M Farhat
- Laboratory for Hydraulic Machines (P.B., M.F.), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - G Erceg
- From the Division of Neuroradiology (P.B., O.B., H.Y., G.E., K.-O.L., M.I.V., Z.K.), University Hospitals of Geneva, Geneva, Switzerland
| | - K-O Lovblad
- From the Division of Neuroradiology (P.B., O.B., H.Y., G.E., K.-O.L., M.I.V., Z.K.), University Hospitals of Geneva, Geneva, Switzerland
| | - M I Vargas
- From the Division of Neuroradiology (P.B., O.B., H.Y., G.E., K.-O.L., M.I.V., Z.K.), University Hospitals of Geneva, Geneva, Switzerland
| | - Z Kulcsar
- From the Division of Neuroradiology (P.B., O.B., H.Y., G.E., K.-O.L., M.I.V., Z.K.), University Hospitals of Geneva, Geneva, Switzerland
| | - V M Pereira
- Division of Neuroradiology (V.M.P.), Department of Medical Imaging .,Division of Neurosurgery (V.M.P.), Department of Surgery, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
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Perhac J, Spaltenstein J, Pereira VM, Schaller K, Brina O, Cabrilo I, Ratib O. Improving workflows of neuro-interventional procedures with autostereoscopic 3D visualization of multi-modality imaging in hybrid interventional suites. Int J Comput Assist Radiol Surg 2015; 11:189-96. [PMID: 26233622 DOI: 10.1007/s11548-015-1268-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 07/14/2015] [Indexed: 11/30/2022]
Abstract
PURPOSE Recent developments in interventional neuroradiology techniques, medical imaging modalities, endovascular stenting and embolization materials lead to an increasing number of patients with cerebral aneurysms and arteriovenous malformations that are eligible for endovascular treatment and have opened new perspectives for novel ways for patient treatment in general. In this paper, we describe a software tool for 3D image fusion of multi-modal acquisitions to assist endovascular treatment of cerebral malformations. The software and an autostereoscopic 3D display were implemented and tested in clinical applications in a hybrid interventional suite that is used for radio-interventional as well as neurosurgical procedures. Our hypothesis is that fusion of image data acquired prior to intervention procedures with images acquired during those procedures should allow better visualizing and navigating through complex cerebral vasculature. This should also improve workflows of neuro-interventional procedures. METHODS Preoperative and intra-operative acquisitions of vascular images of the brain were performed and transferred to a dedicated imaging workstation to be processed with our image fusion and visualization software tool. The tool was developed as a plugin extension to the open-source DICOM viewer OsiriX and is based on a modular and scalable architecture. Several processing modules were implemented to allow spatial co-registration and fusion of preoperative and intra-operative modalities. A special extension was also implemented for interactive autostereosopic, glass-free 3D visualization of fused results. RESULTS The software platform was validated and evaluated in nine in vivo procedures by expert users. All patient cases were related to interventional treatment of neuro-vascular diseases. The emphasis was laid on the added value of spatial co-registration and fusion of preoperative and intra-operative modalities, as well as the overall impact on workflow during the intervention. The co-registered and fused images were visualized on an autostereoscopic 3D monitor installed in hybrid interventional suite. All experiments were evaluated and scored by interventional physicians and technicians. CONCLUSIONS Displaying 3D-4D representations of brain vascular anomalies based on multi-modal acquisitions on a 3D autostereoscopic display is beneficial for the workflow and efficiency of interventional radiologists. The implemented software tool fulfills the premise of applicability of an open-source platform for more advanced, multi-modal visualization and processing of brain vascular structures for image-guided therapeutic interventions.
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Affiliation(s)
- J Perhac
- University Hospitals of Geneva, Geneva, Switzerland.
| | | | - V M Pereira
- University Hospitals of Geneva, Geneva, Switzerland
| | - K Schaller
- University Hospitals of Geneva, Geneva, Switzerland
| | - O Brina
- University Hospitals of Geneva, Geneva, Switzerland
| | - I Cabrilo
- University Hospitals of Geneva, Geneva, Switzerland
| | - O Ratib
- University Hospitals of Geneva, Geneva, Switzerland
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Brina O, Ouared R, Bonnefous O, van Nijnatten F, Bouillot P, Bijlenga P, Schaller K, Lovblad KO, Grünhagen T, Ruijters D, Pereira VM. Intra-aneurysmal flow patterns: illustrative comparison among digital subtraction angiography, optical flow, and computational fluid dynamics. AJNR Am J Neuroradiol 2014; 35:2348-53. [PMID: 25082824 DOI: 10.3174/ajnr.a4063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Digital subtraction angiography is the gold standard vascular imaging and it is used for all endovascular treatment of intracranial anerysms. Optical flow imaging has been described as a potential method to evaluate cerebral hemodynamics through DSA. In this study, we aimed to compare the flow patterns measured during angiography, by using an optical flow method, with those measured by using computational fluid dynamics in intracranial aneurysms. MATERIALS AND METHODS A consecutive series of 21 patients harboring unruptured saccular intracranial aneurysms who underwent diagnostic angiography before treatment was considered. High-frame-rate digital subtraction angiography was performed to obtain an intra-aneurysmal velocity field by following the cardiac-modulated contrast wave through the vascular structures by using optical flow principles. Additionally, computational fluid dynamics modeling was performed for every case by using patient-specific inlet-boundary conditions measured with the optical flow method from both DSA and 3D rotational angiography datasets. Three independent observers compared qualitatively both the inflow direction and the apparent recirculation in regular DSA, optical flow images, and computational fluid dynamics flow patterns for each patient; κ statistics were estimated. RESULTS We included 21 patients. In 14 of these 21, the flow patterns were conclusive and matching between the optical flow images and computational fluid dynamics within the same projection view (κ = .91). However, in only 8 of these 14 patients the optical flow images were conclusive and matching regular DSA images (observer κ = 0.87). In 7 of the 21 patients, the flow patterns in the optical flow images were inconclusive, possibly due to improper projection angles. CONCLUSIONS The DSA-based optical flow technique was considered qualitatively consistent with computational fluid dynamics outcomes in evaluating intra-aneurysmal inflow direction and apparent recirculation. Moreover, the optical flow technique may provide the premises for new solutions for improving the visibility of flow patterns when contrast motion in DSA is not apparent. This technique is a diagnostic method to evaluate intra-aneurysmal flow patterns and could be used in the future for validation and patient evaluation.
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Affiliation(s)
- O Brina
- From the Interventional Neuroradiology Unit (O. Brina, R.O., P. Bouillot, K.-O.L., V.M.P.), Service of Neuroradiology
| | - R Ouared
- From the Interventional Neuroradiology Unit (O. Brina, R.O., P. Bouillot, K.-O.L., V.M.P.), Service of Neuroradiology
| | | | - F van Nijnatten
- Interventional X-Ray (F.v.N., T.G., D.R.), Philips Healthcare, Zürich, Switzerland
| | - P Bouillot
- From the Interventional Neuroradiology Unit (O. Brina, R.O., P. Bouillot, K.-O.L., V.M.P.), Service of Neuroradiology
| | - P Bijlenga
- Service of Neurosurgery (P. Bijlenga, K.S.), University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - K Schaller
- Service of Neurosurgery (P. Bijlenga, K.S.), University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - K-O Lovblad
- From the Interventional Neuroradiology Unit (O. Brina, R.O., P. Bouillot, K.-O.L., V.M.P.), Service of Neuroradiology
| | - T Grünhagen
- Interventional X-Ray (F.v.N., T.G., D.R.), Philips Healthcare, Zürich, Switzerland
| | - D Ruijters
- Interventional X-Ray (F.v.N., T.G., D.R.), Philips Healthcare, Zürich, Switzerland
| | - V Mendes Pereira
- From the Interventional Neuroradiology Unit (O. Brina, R.O., P. Bouillot, K.-O.L., V.M.P.), Service of Neuroradiology Division of Neuroradiology (V.M.P.), Department of Medical Imaging Division of Neurosurgery (V.M.P.), Department of Surgery, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
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12
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Pereira VM, Ouared R, Brina O, Bonnefous O, Satwiaski J, Aerts H, Ruijters D, van Nijnatten F, Perren F, Bijlenga P, Schaller K, Lovblad KO. Quantification of internal carotid artery flow with digital subtraction angiography: validation of an optical flow approach with Doppler ultrasound. AJNR Am J Neuroradiol 2014; 35:156-63. [PMID: 23928145 PMCID: PMC7966491 DOI: 10.3174/ajnr.a3662] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 03/28/2013] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Digital subtraction angiography is the reference standard technique to evaluate intracranial vascular anatomy and used on the endovascular treatment of vascular diseases. A dedicated optical flow-based algorithm was applied to DSA to measure arterial flow. The first quantification results of internal carotid artery flow validated with Doppler sonography are reported. MATERIALS AND METHODS We included 22 consecutive patients who underwent endovascular procedures. To assess the sensitivity of the algorithm to contrast agent-blood mixing dynamics, we acquired high-frame DSA series (60 images/s) with different injection rates: 1.5 mL/s (n = 19), 2.0 mL/s (n = 18), and 3.0 mL/s (n = 13). 3D rotational angiography was used to extract the centerline of the vessel and the arterial section necessary for volume flow calculation. Optical flow was used to measure flow velocities in straight parts of the ICAs; these data were further compared with Doppler sonography data. DSA mean flow rates were linearly regressed on Doppler sonography measurements, and regression slope coefficient bias from value 1 was analyzed within the 95% confidence interval. RESULTS DSA mean flow rates measured with the optical flow approach significantly matched Doppler sonography measurements (slope regression coefficient, b = 0.83 ± 0.19, P = .05) for injection rate = 2.0 mL/s and circulating volumetric blood flow <6 mL/s. For injection rate = 1.5 mL/s, volumetric blood flow <3 mL/s correlated well with Doppler sonography (b = 0.67 ± 0.33, P = .05). Injection rate = 3.0 mL/s failed to provide DSA-optical flow measurements correlating with Doppler sonography because of the lack of measurable pulsatility. CONCLUSIONS A new model-free optical flow technique was tested reliably on the ICA. DSA-based blood flow velocity measurements were essentially validated with Doppler sonography whenever the conditions of measurable pulsatility were achieved (injection rates = 1.5 and 2.0 mL/s).
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Pereira V, Brina O, Marcos Gonzales A, Narata A, Bijlenga P, Schaller K, Lovblad K, Ouared R. Evaluation of the influence of inlet boundary conditions on computational fluid dynamics for intracranial aneurysms: A virtual experiment. J Biomech 2013; 46:1531-9. [DOI: 10.1016/j.jbiomech.2013.03.024] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Revised: 03/14/2013] [Accepted: 03/16/2013] [Indexed: 10/26/2022]
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Pereira VM, Bonnefous O, Ouared R, Brina O, Stawiaski J, Aerts H, Ruijters D, Narata AP, Bijlenga P, Schaller K, Lovblad KO. A DSA-based method using contrast-motion estimation for the assessment of the intra-aneurysmal flow changes induced by flow-diverter stents. AJNR Am J Neuroradiol 2012; 34:808-15. [PMID: 23124641 DOI: 10.3174/ajnr.a3322] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Flow-diverter stents modify intra-aneurysmal blood flow and induce the progressive thrombosis of intracranial aneurysms followed by stable vascular reconstruction. The aim of this study was to report a new method for the appraisal of intracranial blood flow from DSA performed during endovascular treatment procedures. MATERIALS AND METHODS A cohort of 24 patients with unruptured IAs who underwent FDS implantation was prospectively recruited. Pre- and post-DSA sequences in combination with 3D rotational angiography were acquired. The quantification of arterial and intra-aneurysmal flow was accomplished by using an optical flow approach. Flow reduction was assessed by using a new metric termed the mean aneurysm flow amplitude ratio. The correlation between the MAFA ratio and the incidence of aneurysm thrombosis was assessed by using receiver operating characteristic analysis and the Fisher exact test when the optimum Youden index was found. RESULTS The quantification of flow was successfully achieved in 21 of 24 patients (87.5%). On the imaging follow-up, 18 aneurysms developed complete thrombosis (87.5%) and 3 displayed residual circulation (12.5%). The threshold analysis of the MAFA ratio significantly predicted thrombosis at 12 months below a threshold of 1.03 (P=.035). There was no significant correlation between the time for complete occlusion of the aneurysm and contrast stagnation inside the aneurysm after treatment (P>.05). CONCLUSIONS The MAFA ratio based on DSA flow quantification appears to be a reliable predictor for the assessment of stent treatment outcomes in this small study. These results open the door for perioperative flow quantification and provide indices that may help clinicians make appropriate intraprocedural decisions.
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Affiliation(s)
- V M Pereira
- Interventional Neuroradiology Unit, Service of Neuroradiology, University Hospital of Geneva, Geneva, Switzerland.
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Bijlenga P, Kotowski M, Schatlo B, Radovanovic I, Momjian S, Slegers L, Brina O, Rüfenacht D, Schaller C. Salle d’opération combinée avec angiographie intraopératoire rotationnelle : une note technique sur l’expérience de Genève. Neurochirurgie 2009. [DOI: 10.1016/j.neuchi.2009.08.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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