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Korte J, Gaidzik F, Larsen N, Schütz E, Damm T, Wodarg F, Hövener JB, Jansen O, Janiga G, Berg P, Pravdivtseva MS. In vitro and in silico assessment of flow modulation after deploying the Contour Neurovascular System in intracranial aneurysm models. J Neurointerv Surg 2024; 16:815-823. [PMID: 37852752 PMCID: PMC11287554 DOI: 10.1136/jnis-2023-020403] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 07/15/2023] [Indexed: 10/20/2023]
Abstract
BACKGROUND The novel Contour Neurovascular System (Contour) has been reported to be efficient and safe for the treatment of intracranial, wide-necked bifurcation aneurysms. Flow in the aneurysm and posterior cerebral arteries (PCAs) after Contour deployment has not been analyzed in detail yet. However, this information is crucial for predicting aneurysm treatment outcomes. METHODS Time-resolved three-dimensional velocity maps in 14 combinations of patient-based basilar tip aneurysm models with and without Contour devices (sizes between 5 and 14 mm) were analyzed using four-dimensionsal (4D) flow MRI and numerical/image-based flow simulations. A complex virtual processing pipeline was developed to mimic the experimental shape and position of the Contour together with the simulations. RESULTS On average, the Contour significantly reduced intra-aneurysmal flow velocity by 67% (mean w/ = 0.03m/s; mean w/o = 0.12m/s; p-value=0.002), and the time-averaged wall shear stress by more than 87% (mean w/ = 0.17Pa; mean w/o = 1.35Pa; p-value=0.002), as observed by numerical simulations. Furthermore, a significant reduction in flow (P<0.01) was confirmed by the neck inflow rate, kinetic energy, and inflow concentration index after Contour deployment. Notably, device size has a stronger effect on reducing flow than device positioning. However, positioning affected flow in the PCAs, while being robust in effectively reducing flow. CONCLUSIONS This study showed the high efficacy of the Contour device in reducing flow within aneurysms regardless of the exact position. However, we observed an effect on the flow in PCAs, which needs to be investigated further.
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Affiliation(s)
- Jana Korte
- Laboratory of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
- Research campus STIMULATE, University of Magdeburg, Magdeburg, Germany
| | - Franziska Gaidzik
- Laboratory of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
- Research campus STIMULATE, University of Magdeburg, Magdeburg, Germany
| | - Naomi Larsen
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany
| | - Erik Schütz
- Research campus STIMULATE, University of Magdeburg, Magdeburg, Germany
| | - Timo Damm
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany
| | - Fritz Wodarg
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany
| | - Jan-Bernd Hövener
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany
| | - Olav Jansen
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany
| | - Gábor Janiga
- Laboratory of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
- Research campus STIMULATE, University of Magdeburg, Magdeburg, Germany
| | - Philipp Berg
- Research campus STIMULATE, University of Magdeburg, Magdeburg, Germany
- Department of Healthcare Telematics and Medical Engineering, University of Magdeburg, Magdeburg, Germany
| | - Mariya S Pravdivtseva
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany
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Ozpeynirci Y, Gorodezky M, Sanches AF, Mandava S, Solana AB, Liebig T. Impact of Various Non-Contrast-Enhanced MRA Techniques on Lumen Visibility in Vascular Flow Models with a Surpass Evolve Flow Diverter. Diagnostics (Basel) 2024; 14:1146. [PMID: 38893675 PMCID: PMC11171646 DOI: 10.3390/diagnostics14111146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 05/18/2024] [Accepted: 05/27/2024] [Indexed: 06/21/2024] Open
Abstract
BACKGROUND Silent MRA has shown promising results in evaluating the stents used for intracranial aneurysm treatment. A deep learning-based denoising and deranging algorithm was recently introduced by GE HealthCare. The purpose of this study was to compare the performance of several MRA techniques regarding lumen visibility in silicone models with flow diverter stents. METHODS Two Surpass Evolve stents of different sizes were implanted in two silicone tubes. The tubes were placed in separate boxes in the straight position and in two different curve configurations and connected to a pulsatile pump to construct a flow loop. Using a 3.0T MRI scanner, TOF and silent MRA images were acquired, and deep learning reconstruction was applied to the silent MRA dataset. The intraluminal signal intensity in the stent (SIin-stent), in the tube outside the stent (SIvessel), and of the background (SIbg) were measured for each scan. RESULTS The SIin-stent/SIbg and SIin-stent/SIv ratios were higher in the silent scans and DL-based reconstructions than in the TOF images. The stent tips created severe artefacts in the TOF images, which could not be observed in the silent scans. CONCLUSIONS Our study demonstrates that the DL reconstruction algorithm improves the quality of the silent MRA technique in evaluating the flow diverter stent patency.
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Affiliation(s)
- Yigit Ozpeynirci
- Institute for Diagnostic and Interventional Neuroradiology, University Hospital, Ludwig-Maximilians-University (LMU), Marchioninistr. 15, 81377 Munich, Germany; (A.F.S.); (T.L.)
| | | | - Augusto Fava Sanches
- Institute for Diagnostic and Interventional Neuroradiology, University Hospital, Ludwig-Maximilians-University (LMU), Marchioninistr. 15, 81377 Munich, Germany; (A.F.S.); (T.L.)
| | | | - Ana Beatriz Solana
- GE HealthCare, 80807 Munich, Germany; (M.G.); (A.B.S.)
- Center for Neuroimaging Sciences, King’s College London, London SE1 7EH, UK
| | - Thomas Liebig
- Institute for Diagnostic and Interventional Neuroradiology, University Hospital, Ludwig-Maximilians-University (LMU), Marchioninistr. 15, 81377 Munich, Germany; (A.F.S.); (T.L.)
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Oliver AA, Koons EK, Trester PS, Kleinow JE, Jonsgaard RS, Vercnocke AJ, Bilgin C, Kadirvel R, Leng S, Lu A, Dragomir-Daescu D, Kallmes DF. Medical Imaging Compatibility of Magnesium- and Iron-Based Bioresorbable Flow Diverters. AJNR Am J Neuroradiol 2023; 44:668-674. [PMID: 37169543 PMCID: PMC10249688 DOI: 10.3174/ajnr.a7873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 04/16/2023] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND PURPOSE Bioresorbable flow diverters are under development to mitigate complications associated with conventional flow-diverter technology. One proposed advantage is the ability to reduce metal-induced artifacts in follow-up medical imaging. In the current work, the medical imaging compatibility of magnesium- and iron-based bioresorbable flow diverters is assessed relative to an FDA-approved control in phantom models. MATERIALS AND METHODS Bioresorbable flow diverters, primarily composed of braided magnesium or antiferromagnetic iron alloy wires, were compared with an FDA-approved control flow diverter. The devices were assessed for MR imaging safety in terms of magnetically induced force and radiofrequency heating using 1.5T, 3T, and 7T field strength clinical scanners. The devices were deployed in phantom models, and metal-induced image artifacts were assessed in the 3 MR imaging scanners and a clinical CT scanner following clinical scan protocols; device visibility was assessed under fluoroscopy. RESULTS The magnesium-based bioresorbable flow diverter, iron-based bioresorbable flow diverter, and the control device all demonstrated MR imaging safety in terms of magnetically induced force and radiofrequency heating at all 3 field strengths. The bioresorbable flow diverters did not elicit excessive MR imaging artifacts at any field strength relative to the control. Furthermore, the bioresorbable flow diverters appeared to reduce blooming artifacts in CT relative to the control. The iron-based bioresorbable flow diverter and control device were visible under standard fluoroscopy. CONCLUSIONS We have demonstrated the baseline medical imaging compatibility of magnesium and antiferromagnetic iron alloy bioresorbable flow diverters. Future work will evaluate the medical imaging characteristics of the bioresorbable flow diverters in large-animal models.
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Affiliation(s)
- A A Oliver
- From the Department of Biomedical Engineering and Physiology (A.A.O., E.K.K., S.L., D.D.-D, D.F.K.), Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
- Physiology and Biomedical Engineering (A.A.O., D.D.-D.)
| | - E K Koons
- From the Department of Biomedical Engineering and Physiology (A.A.O., E.K.K., S.L., D.D.-D, D.F.K.), Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
| | - P S Trester
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
| | - J E Kleinow
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
| | - R S Jonsgaard
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
| | - A J Vercnocke
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
| | - C Bilgin
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
| | - R Kadirvel
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
- Neurosurgery (R.K.), Mayo Clinic, Rochester, Minnesota
| | - S Leng
- From the Department of Biomedical Engineering and Physiology (A.A.O., E.K.K., S.L., D.D.-D, D.F.K.), Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
| | - A Lu
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
| | - D Dragomir-Daescu
- From the Department of Biomedical Engineering and Physiology (A.A.O., E.K.K., S.L., D.D.-D, D.F.K.), Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota
- Physiology and Biomedical Engineering (A.A.O., D.D.-D.)
| | - D F Kallmes
- From the Department of Biomedical Engineering and Physiology (A.A.O., E.K.K., S.L., D.D.-D, D.F.K.), Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota
- Departments of Radiology (A.A.O., E.K.K., P.S.T., J.E.K., R.S.J., A.J.V., C.B., R.K. S.L., A.L., D.F.K.)
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Sache A, Reymond P, Brina O, Jung B, Farhat M, Vargas MI. Near-wall hemodynamic parameters quantification in in vitro intracranial aneurysms with 7 T PC-MRI. MAGMA (NEW YORK, N.Y.) 2023; 36:295-308. [PMID: 37072539 PMCID: PMC10140017 DOI: 10.1007/s10334-023-01082-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 03/20/2023] [Accepted: 03/21/2023] [Indexed: 04/20/2023]
Abstract
OBJECTIVE Wall shear stress (WSS) and its derived spatiotemporal parameters have proven to play a major role on intracranial aneurysms (IAs) growth and rupture. This study aims to demonstrate how ultra-high field (UHF) 7 T phase contrast magnetic resonance imaging (PC-MRI) coupled with advanced image acceleration techniques allows a highly resolved visualization of near-wall hemodynamic parameters patterns in in vitro IAs, paving the way for more robust risk assessment of their growth and rupture. MATERIALS AND METHODS We performed pulsatile flow measurements inside three in vitro models of patient-specific IAs using 7 T PC-MRI. To this end, we built an MRI-compatible test bench, which faithfully reproduced a typical physiological intracranial flow rate in the models. RESULTS The ultra-high field 7 T images revealed WSS patterns with high spatiotemporal resolution. Interestingly, the high oscillatory shear index values were found in the core of low WSS vortical structures and in flow stream intersecting regions. In contrast, maxima of WSS occurred around the impinging jet sites. CONCLUSIONS We showed that the elevated signal-to-noise ratio arising from 7 T PC-MRI enabled to resolve high and low WSS patterns with a high degree of detail.
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Affiliation(s)
- Antoine Sache
- Department of Mechanical Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
| | - Philippe Reymond
- Division of Neuroradiology, Geneva University Hospital, University of Geneva, Geneva, Switzerland
| | - Olivier Brina
- Division of Neuroradiology, Geneva University Hospital, University of Geneva, Geneva, Switzerland
| | - Bernd Jung
- Department of Diagnostic, Interventional and Paediatric Radiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Mohamed Farhat
- Department of Mechanical Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Maria Isabel Vargas
- Division of Neuroradiology, Geneva University Hospital, University of Geneva, Geneva, Switzerland
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Kato H, Ootani N, Abiru K, Okahara M. Investigating Signal Loss due to a Carotid Artery Stent in 3D-TOF-MRA. Magn Reson Med Sci 2021; 20:303-311. [PMID: 32963183 PMCID: PMC8424025 DOI: 10.2463/mrms.mp.2019-0083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Purpose: In this study, we investigated the factors of signal loss out because of the presence of a stent and optimized imaging parameters for improvement in depiction ability. Methods: We investigated the relationship between the stent type and magnetic susceptibility effect by measuring the signal value between the inside and outside of the stent with different Bw and TE for two different kinds of stents respectively. Similarly, flip angles were changed for two different kinds of stents respectively to the signal intensity between the inside and the outside of the stent was measured, in which examine the relationship between the stent type and the Ernst angles in RF-shielding effect. The conventional imaging parameters and the optimum imaging parameters for each stent obtained from the result of the phantom experiment were examined. Optimized 3D time-of-flight MR angiography (3D-TOF-MRA) was performed and compared with conventional 3D-TOF-MRA and computed tomography angiography (CTA). Results: The influence of the magnetic susceptibility effect is small in the central part of Carotid Wallstent and in PRECISE, and large in the Carotid Wallstent at the both ends. The influence of RF-shielding effect was large at PRECISE, where the Ernst angle was greatly shifted while the effect is no longer influenced at Carotid Wallstent. Both Carotid Wallstent and PRECISE made imaging capability improved by optimizing the imaging parameters. Conclusion: During clinical imaging of patients post-carotid artery stenting (CAS) using our protocol, the ability to visualize blood vessels was improved. Thus, we demonstrated that the ability of 3D-TOF-MRA post-CAS was improved via optimizing imaging parameters.
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Affiliation(s)
- Hiroshi Kato
- Radiology Department, Federation of National Public Service Personnel Mutual Aid Associations Shinbeppu Hospital
| | - Norio Ootani
- Radiology Department, Federation of National Public Service Personnel Mutual Aid Associations Shinbeppu Hospital
| | - Kentaro Abiru
- Radiology Department, Federation of National Public Service Personnel Mutual Aid Associations Shinbeppu Hospital
| | - Mika Okahara
- Radiology Department, Federation of National Public Service Personnel Mutual Aid Associations Shinbeppu Hospital
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Velvaluri P, Pravdivtseva MS, Hensler J, Wodarg F, Jansen O, Quandt E, Hövener JB. A realistic way to investigate the design, and mechanical properties of flow diverter stents. Expert Rev Med Devices 2021; 18:569-579. [PMID: 33890849 DOI: 10.1080/17434440.2021.1920923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
PURPOSE Braided flow diverters (FD) are highly sophisticated, delicate, and intricate mechanical devices used to treat intracranial aneurysms. Testing such devices in vitro, however, remains an unsolved challenge. Here, we evaluate methods to measure flow, design and mechanical properties in vitro. METHODS Flow properties, cell porosity, pore density, and cell area were evaluated under geometrically realistic conditions by placing FDs in patient-derived, 3D-printed models of human vasculature. 4D flow MRI was used to measure fluid dynamics. Laser microscopy was used to measure the design properties of the FDs. New methods were developed to investigate the bending, circumferential, and longitudinal radial force of the FDs continuously over varying diameters. RESULTS The placement and flow properties of the FD in the vasculature models were successfully measured by MRI, although artifacts occurred. Likewise, the porosity, pore density, and cell area were successfully measured inside of the models using a laser microscope. The newly developed mechanical methods allowed to measure the indicated forces - to our knowledge for the first time - continuously. CONCLUSION Modern and specifically tailored techniques, some of which were presented here for the first time, allow detailed insights into the flow, design, and mechanical properties of braided flow diverter stents.
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Affiliation(s)
| | - Mariya S Pravdivtseva
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany
| | - Johannes Hensler
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany
| | - Fritz Wodarg
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany
| | - Olav Jansen
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany
| | - Eckhard Quandt
- Chair of Inorganic Functional Materials, Kiel University, Kiel, Germany
| | - Jan-Bernd Hövener
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany
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Magnetic particle imaging for artifact-free imaging of intracranial flow diverter stents: A phantom study. Phys Med 2021; 88:65-70. [PMID: 34192659 DOI: 10.1016/j.ejmp.2021.06.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/10/2021] [Accepted: 06/21/2021] [Indexed: 11/20/2022] Open
Abstract
PURPOSE Magnetic Particle Imaging (MPI) is a new, background- and radiation-free tomographic imaging method that enables near real-time imaging of superparamagnetic iron-oxide nanoparticles (SPIONs) with high temporal and spatial resolution. This phantom study aims to investigate the potential of MPI for visualization of the stent lumen in intracranial flow diverters (FD). METHODS Nitinol FD of different dimensions (outer diameter: 3.5 mm, 4.0 mm, 5.5 mm; total length: 22-40 mm) were scanned in vascular phantoms in a custom-built MPI scanner (in-plane resolution: ~ 2 mm, field of view: 65 mm length, 29 mm diameter). Phantoms were filled with diluted (1:50) SPION tracer agent Ferucarbotran (10 µmol (Fe)/ml; NaCL). Each phantom was measured in 32 different projections (overall acquisition time per image: 3200 ms, 5averages). After image reconstruction from raw data, two radiologists assessed image quality using a 5-point Likert scale. The signal intensity profile was measured using a semi-automatic evaluation tool. RESULTS MPI visualized the lumen of all FD without relevant differences between the stented vessel phantom and the reference phantom. At 3.5 mm image quality was slightly inferior to the larger diameters. The FD themselves neither generated an MPI signal nor did they lead to relevant imaging artifacts. Ratings of both radiologists showed no significant difference, interrater reliability was good (ICC 0.84). A quantitative evaluation of the signal intensity profile did not reveal any significant differences (p > 0.05) either. CONCLUSION MPI visualizes the lumen of nitinol FD stents in vessel phantoms without relevant stent-induced artifacts.
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Artifact quantification of venous stents in the MRI environment: Differences between braided and laser-cut designs. Phys Med 2021; 88:1-8. [PMID: 34147868 DOI: 10.1016/j.ejmp.2021.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/19/2021] [Accepted: 06/04/2021] [Indexed: 02/06/2023] Open
Abstract
PURPOSE To quantify B0- and B1-induced imaging artifacts of braided venous stents and to compare the artifacts to a set of laser-cut stents used in venous interventions. METHODS Three prototypes of braided venous stents with different geometries were tested in vitro. B0 field distortion maps were measured via the frequency shift Δf using multi-echo imaging. B1 distortions were quantified using the double angle method. The relative amplitudes B1rel were calculated to compare the intraluminal alteration of B1. Measurements were repeated with the stents in three different orientations: parallel, diagonal and orthogonal to B0. RESULTS At 1.5 T, the braided stents induced a maximum frequency shift of Δfx<100Hz. Signal voids were limited to a distance of 2 mm to the stent walls at an echo time of 3 ms. No substantial difference in the B0 field distortions was seen between laser-cut and braided venous stents. B1rel maps showed strongly varying distortion patterns in the braided stents with the mean intraluminal B1rel ranging from 63±18% in prototype 1 to 98±38% in prototype 2. Compared to laser-cut stents the braided stents showed a 5 to 9 times higher coefficient of variation of the intraluminal B1rel. CONCLUSION Braided venous stent prototypes allow for MR imaging of the intraluminal area without substantial signal voids due to B0-induced artifacts. Whereas B1 is attenuated homogeneously in laser-cut stents, the B1 distortion in braided stents is more inhomogeneous and shows areas with enhanced amplitude. This could potentially be used in braided stent designs for intraluminal signal amplification.
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Halitcan B, Bige S, Sinan B, Ilkay A, Ergun D, Fatih A, Anil A. The implications of magnetic resonance angiography artifacts caused by different types of intracranial flow diverters. J Cardiovasc Magn Reson 2021; 23:69. [PMID: 34092251 PMCID: PMC8182930 DOI: 10.1186/s12968-021-00753-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/06/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Serial cerebral angiographic imaging is necessary to ensure cerebral aneurysm occlusion after flow diverter placement. Time-of-flight (TOF)-magnetic resonance angiography (MRA) is used for this purpose due to its lack of radiation, contrast media and complications. The comparative diagnostic yield of TOF-MRA for different flow diverters has not been previously analyzed. PURPOSE To evaluate the diagnostic accuracy of TOF-MRA in cerebral aneurysms treated w divertersith different flow diverters. MATERIALS AND METHODS Flow-diverted patients whose cerebral follow-up MRA and digital subtraction angiograms (DSA) were obtained within 6 weeks were retrospectively identified. The DSA (as gold standard) and MRA images of these patients were compared by two readers (blinded to both patient data and endovascular procedure data) for residual aneurysms and the status of the parent artery for each type of flow diverter. In a second group of patients, magnetic susceptibility artifacts were manually measured and compared for different FDs. RESULTS Seventy-six patients (85 aneurysms) were included in group one, and 86 patients (95 aneurysms) were included in group 2. TOF-MRA and DSA showed almost perfect agreement for residual aneurysms (κ = 0.88, p < 0.001) (positive predictive value (PPV) = 1.00, specificity = 1.00, negative predictive value (NPV) = 0.89, sensitivity = 0.89). Intermodality agreement (κ = 0.97 vs. κ = 0.74, p < 0.005) and sensitivity (0.97 vs. 0.77, NPV: 0.96 vs. 0.77) were highest with nitinol stents. MRA and DSA showed no agreement for occluded or stenotic parent vessels (κ = 0.13, p = 0.015, specificity = 0.44, NPV = 1.00, sensitivity = 1.00). Specificity was lower in chromium-cobalt based FDs than in nitinol devices (specificity = 0.08 vs. 0.60). Chromium-cobalt stents generated the largest artifacts (p < 0.005). The size of the device-related artifact, in millimeters, increased in respective order, for the Silk, Derivo, Pipeline and Surpass devices. CONCLUSION Unlike DSA, TOF-MRA is susceptible to dissimilarities between flow diverters. MRA is not well-suited for research studies comparing different flow diverters. Nitinol FDs appear to be advantageous for TOF-MRA follow-up so as not to miss small aneurysm remnants or clinically relevant parent artery stenosis.
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Affiliation(s)
- Batur Halitcan
- Department of Radiology, Ministry of Health Ankara City Hospital, Ankara, Turkey
| | - Sayin Bige
- Department of Radiology, Ministry of Health Ankara City Hospital, Ankara, Turkey
| | - Balci Sinan
- Department of Radiology, Hacettepe University Hospitals, Ankara, Turkey
| | - Akmangit Ilkay
- Department of Radiology, Ministry of Health Ankara City Hospital, Ankara, Turkey
| | - Daglioglu Ergun
- Department of Neurosurgery, Ministry of Health Ankara City Hospital, Ankara, Turkey
| | - Alagoz Fatih
- Department of Neurosurgery, Ministry of Health Ankara City Hospital, Ankara, Turkey
| | - Arat Anil
- Department of Radiology, Hacettepe University Hospitals, Ankara, Turkey.
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Terem I, Dang L, Champagne A, Abderezaei J, Pionteck A, Almadan Z, Lydon AM, Kurt M, Scadeng M, Holdsworth SJ. 3D amplified MRI (aMRI). Magn Reson Med 2021; 86:1674-1686. [PMID: 33949713 PMCID: PMC8252598 DOI: 10.1002/mrm.28797] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/18/2021] [Accepted: 03/17/2021] [Indexed: 12/17/2022]
Abstract
Purpose Amplified MRI (aMRI) has been introduced as a new method of detecting and visualizing pulsatile brain motion in 2D. Here, we improve aMRI by introducing a novel 3D aMRI approach. Methods 3D aMRI was developed and tested for its ability to amplify sub‐voxel motion in all three directions. In addition, 3D aMRI was qualitatively compared to 2D aMRI on multi‐slice and 3D (volumetric) balanced steady‐state free precession cine data and phase contrast (PC‐MRI) acquired on healthy volunteers at 3T. Optical flow maps and 4D animations were produced from volumetric 3D aMRI data. Results 3D aMRI exhibits better image quality and fewer motion artifacts compared to 2D aMRI. The tissue motion was seen to match that of PC‐MRI, with the predominant brain tissue displacement occurring in the cranial‐caudal direction. Optical flow maps capture the brain tissue motion and display the physical change in shape of the ventricles by the relative movement of the surrounding tissues. The 4D animations show the complete brain tissue and cerebrospinal fluid (CSF) motion, helping to highlight the “piston‐like” motion of the ventricles. Conclusions Here, we introduce a novel 3D aMRI approach that enables one to visualize amplified cardiac‐ and CSF‐induced brain motion in striking detail. 3D aMRI captures brain motion with better image quality than 2D aMRI and supports a larger amplification factor. The optical flow maps and 4D animations of 3D aMRI may open up exciting applications for neurological diseases that affect the biomechanics of the brain and brain fluids.
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Affiliation(s)
- Itamar Terem
- Department of Electrical Engineering, Stanford University, Stanford, California, USA.,Department of Structural Biology, Stanford University, Stanford, California, USA
| | - Leo Dang
- Department of Anatomy and Medical Imaging & Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.,Mātai Medical Research Institute, Gisborne-Tairāwhiti, New Zealand
| | - Allen Champagne
- Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
| | - Javid Abderezaei
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA
| | - Aymeric Pionteck
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA
| | - Zainab Almadan
- Department of Anatomy and Medical Imaging & Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Anna-Maria Lydon
- Centre for Advanced MRI, University of Auckland, Auckland, New Zealand
| | - Mehmet Kurt
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA.,Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Miriam Scadeng
- Department of Anatomy and Medical Imaging & Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.,Mātai Medical Research Institute, Gisborne-Tairāwhiti, New Zealand.,Department of Radiology, University of California, San Diego, California, USA
| | - Samantha J Holdsworth
- Department of Anatomy and Medical Imaging & Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.,Mātai Medical Research Institute, Gisborne-Tairāwhiti, New Zealand
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11
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Pravdivtseva MS, Peschke E, Lindner T, Wodarg F, Hensler J, Gabbert D, Voges I, Berg P, Barker AJ, Jansen O, Hövener JB. 3D-printed, patient-specific intracranial aneurysm models: From clinical data to flow experiments with endovascular devices. Med Phys 2021; 48:1469-1484. [PMID: 33428778 DOI: 10.1002/mp.14714] [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: 07/26/2020] [Revised: 12/30/2020] [Accepted: 12/31/2020] [Indexed: 12/14/2022] Open
Abstract
PURPOSE Flow models of intracranial aneurysms (IAs) can be used to test new and existing endovascular treatments with flow modulation devices (FMDs). Additionally, 4D flow magnetic resonance imaging (MRI) offers the ability to measure hemodynamics. This way, the effect of FMDs can be determined noninvasively and compared to patient data. Here, we describe a cost-effective method for producing flow models to test the efficiency of FMDs with 4D flow MRI. METHODS The models were based on human radiological data (internal carotid and basilar arteries) and printed in 3D with stereolithography. The models were printed with three different printing layers (25, 50, and 100 µm thickness). To evaluate the models in vitro, 3D rotational angiography, time-of-flight MRI, and 4D flow MRI were employed. The flow and geometry of one model were compared with in vivo data. Two FMDs (FMD1 and FMD2) were deployed into two different IA models, and the effect on the flow was estimated by 4D flow MRI. RESULTS Models printed with different layer thicknesses exhibited similar flow and little geometric variation. The mean spatial difference between the vessel geometry measured in vivo and in vitro was 0.7 ± 1.1 mm. The main flow features, such as vortices in the IAs, were reproduced. The velocities in the aneurysms were similar in vivo and in vitro (mean velocity magnitude: 5.4 ± 7.6 and 7.7 ± 8.6 cm/s, maximum velocity magnitude: 72.5 and 55.1 cm/s). By deploying FMDs, the mean velocity was reduced in the IAs (from 8.3 ± 10 to 4.3 ± 9.32 cm/s for FMD1 and 9.9 ± 12.1 to 2.1 ± 5.6 cm/s for FMD2). CONCLUSIONS The presented method allows to produce neurovascular models in approx. 15 to 30 h. The resulting models were found to be geometrically accurate, reproducing the main flow patterns, and suitable for implanting FMDs as well as 4D flow MRI.
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Affiliation(s)
- Mariya S Pravdivtseva
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Kiel, Germany.,Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany.,University of Kiel, Kiel, Germany
| | - Eva Peschke
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Kiel, Germany.,Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany.,University of Kiel, Kiel, Germany
| | - Thomas Lindner
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany.,Department of Diagnostic and Interventional Neuroradiology, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Fritz Wodarg
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany
| | - Johannes Hensler
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany
| | - Dominik Gabbert
- Department of Congenital Heart Disease and Pediatric Cardiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany
| | - Inga Voges
- Department of Congenital Heart Disease and Pediatric Cardiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany
| | - Philipp Berg
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany.,Research Campus STIMULATE, University of Magdeburg, Magdeburg, Germany
| | - Alex J Barker
- Department of Radiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Olav Jansen
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany
| | - Jan-Bernd Hövener
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Kiel, Germany.,Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel, Germany.,University of Kiel, Kiel, Germany
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12
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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] [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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