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Righini P, Secchi F, Mazzaccaro D, Giese D, Galligani M, Avishay D, Capra D, Monti CB, Nano G. Four-Dimensional Flow MRI for the Evaluation of Aortic Endovascular Graft: A Pilot Study. Diagnostics (Basel) 2023; 13:2113. [PMID: 37371010 DOI: 10.3390/diagnostics13122113] [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: 04/27/2023] [Revised: 05/28/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023] Open
Abstract
We aimed to explore the feasibility of 4D flow magnetic resonance imaging (MRI) for patients undergoing thoracic aorta endovascular repair (TEVAR). We retrospectively evaluated ten patients (two female), with a mean (±standard deviation) age of 61 ± 20 years, undergoing MRI for a follow-up after TEVAR. All 4D flow examinations were performed using a 1.5-T system (MAGNETOM Aera, Siemens Healthcare, Erlangen, Germany). In addition to the standard examination protocol, a 4D flow-sensitive 3D spatial-encoding, time-resolved, phase-contrast prototype sequence was acquired. Among our cases, flow evaluation was feasible in all patients, although we observed some artifacts in 3 out of 10 patients. Three individuals displayed a reduced signal within the vessel lumen where the endograft was placed, while others presented with turbulent or increased flow. An aortic endograft did not necessarily hinder the visualization of blood flow through 4D flow sequences, although the graft could generate flow artifacts in some cases. A 4D Flow MRI may represent the ideal tool to follow up on both healthy subjects deemed to be at an increased risk based on their anatomical characteristics or patients submitted to TEVAR for whom a surveillance protocol with computed tomography angiography would be cumbersome and unjustified.
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Affiliation(s)
- Paolo Righini
- Operative Unit of Vascular & Endovascular Unit, IRCCS Policlinico San Donato, Via Morandi 30, 20097 San Donato Milanese, Italy
| | - Francesco Secchi
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Via Mangiagalli 31, 20133 Milano, Italy
- Unit of Radiology, IRCCS Policlinico San Donato, Via Morandi 30, 20097 San Donato Milanese, Italy
| | - Daniela Mazzaccaro
- Operative Unit of Vascular & Endovascular Unit, IRCCS Policlinico San Donato, Via Morandi 30, 20097 San Donato Milanese, Italy
| | - Daniel Giese
- Magnetic Resonance, Siemens Healthcare GmbH, 91050 Erlangen, Germany
| | - Marina Galligani
- Operative Unit of Vascular & Endovascular Unit, IRCCS Policlinico San Donato, Via Morandi 30, 20097 San Donato Milanese, Italy
| | - Dor Avishay
- Operative Unit of Vascular & Endovascular Unit, IRCCS Policlinico San Donato, Via Morandi 30, 20097 San Donato Milanese, Italy
| | - Davide Capra
- Postgraduation School in Radiodiagnostics, Università degli Studi di Milano, Via Festa del Perdono 7, 20122 Milano, Italy
| | - Caterina Beatrice Monti
- Postgraduation School in Radiodiagnostics, Università degli Studi di Milano, Via Festa del Perdono 7, 20122 Milano, Italy
| | - Giovanni Nano
- Operative Unit of Vascular & Endovascular Unit, IRCCS Policlinico San Donato, Via Morandi 30, 20097 San Donato Milanese, Italy
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Via Mangiagalli 31, 20133 Milano, Italy
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Accuracy of Phase-Contrast Velocity Mapping Proximal and Distal to Stent Artifact During Cardiac Magnetic Resonance Imaging. Am J Cardiol 2018; 121:1634-1638. [PMID: 29776653 DOI: 10.1016/j.amjcard.2018.02.050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 02/19/2018] [Accepted: 02/26/2018] [Indexed: 11/20/2022]
Abstract
Little data are available on the accuracy of phase-contrast magnetic resonance imaging (PC-MRI) velocity mapping in the vicinity of intravascular metal stents other than nitinol stents. Therefore, we sought to determine this accuracy using in vitro experiments. An in vitro flow phantom was used with 3 stent types: (1) 316L stainless steel, (2) nitinol self-expanding, and (3) platinum-iridium. Steady and pulsatile flow was delivered with a magnetic resonance imaging-compatible pump (CardioFlow 5000, Shelley Medical, London, Ontario, Canada). Flows were measured using a transit time flow meter (ME13PXN, Transonic, Inc, Ithaca, New York). Mean flows ranged from 0.5 to 7 L/min. For each condition, 5 PC-MRI acquisitions were made: within the stent, immediately adjacent to both edges of the stent artifact, and 1 cm upstream and downstream of the artifact. Mean PC-MRI flows were calculated by segmenting the tube lumen using clinical software (ARGUS, Siemens, Inc, Erlangen, Germany). PC-MRI and flow meter flows were compared by location and stent type using linear regression, Bland-Altman, and intraclass correlation (ICC). PC-MRI flows within the stent artifact were inaccurate for all stents studied, generally underestimating flow meter-measured flow. Agreement between PC-MRI and flow meter-measured flows was excellent for all stent types, both immediately adjacent to and 1 cm away from the edge of the stent artifact. Agreement was highest for the platinum-iridium stent (R = 0.999, ICC = 0.999) and lowest for the nitinol stent (R = 0.993, ICC = 0.987). In conclusion, PC-MRI flows are highly accurate just upstream and downstream of a variety of clinically used stents, supporting its use to directly measure flows in stented vessels.
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Zheng Q, Chu Z, Li X, Kang H, Yang X, Fan Y. The Effect of Fluid Shear Stress on the In Vitro Release Kinetics of Sirolimus from PLGA Films. Polymers (Basel) 2017; 9:618. [PMID: 30965925 PMCID: PMC6418679 DOI: 10.3390/polym9110618] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/31/2017] [Accepted: 11/10/2017] [Indexed: 12/27/2022] Open
Abstract
Drug-carrying coatings of stents implanted in blood vessels are exposed to various blood flows. This study investigated the effect of fluid shear stress on the in vitro release kinetics of sirolimus from poly(lactic-co-glycolic acid) (PLGA) films. The homemade parallel plate flow chamber was used to exert quantitative shear stress on the sirolimus-carrying film. By adjusting the flow rate of the release media in the chamber, three levels of shear stress (3.6, 12.0, and 36.0 dyn/cm²) were respectively applied. For each level of shear stress employed, the release kinetics of sirolimus from the PLGA films exhibited a four-phase profile: an initial burst release phase (Phase I), a lag phase (Phase II), a second burst release phase (Phase III), and a terminal release phase (Phase IV). During Phases I and II, sirolimus was released slowly and in small amounts (<10%); however, during Phases III and IV, the drug release increased considerably. Comparisons of different shear stresses indicated that greater shear stress resulted in earlier and faster sirolimus release, with more cumulative drug release observed. PLGA film degradations (molecular weight reduction, mass loss, and surface topographical variations) were also investigated to better explain the observed drug release behavior. Consequently, fluid shear stress was found to significantly accelerate the release of sirolimus from the PLGA matrices. Therefore, this study could provide a practical method for evaluating the in vitro drug release from polymer matrices under uniform shear stress, and might help improve the design of biodegradable coatings on drug-eluting stents.
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Affiliation(s)
- Quan Zheng
- School of Biological Science and Medical Engineering, Beihang University, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing 100083, China.
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 102402, China.
| | - Zhaowei Chu
- Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age Disability, National Research Center for Rehabilitation Technical Aids, Beijing 100176, China.
| | - Xiaoming Li
- School of Biological Science and Medical Engineering, Beihang University, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing 100083, China.
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 102402, China.
| | - Hongyan Kang
- School of Biological Science and Medical Engineering, Beihang University, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing 100083, China.
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 102402, China.
| | - Xiao Yang
- School of Biological Science and Medical Engineering, Beihang University, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing 100083, China.
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 102402, China.
| | - Yubo Fan
- School of Biological Science and Medical Engineering, Beihang University, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing 100083, China.
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 102402, China.
- Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age Disability, National Research Center for Rehabilitation Technical Aids, Beijing 100176, China.
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Four-Dimensional Phase Contrast Magnetic Resonance Imaging Protocol Optimization Using Patient-Specific 3-Dimensional Printed Replicas for In Vivo Imaging Before and After Flow Diverter Placement. World Neurosurg 2017. [DOI: 10.1016/j.wneu.2017.06.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Rengier F, Delles M, Eichhorn J, Azad YJ, von Tengg-Kobligk H, Ley-Zaporozhan J, Dillmann R, Kauczor HU, Unterhinninghofen R, Ley S. Noninvasive 4D pressure difference mapping derived from 4D flow MRI in patients with repaired aortic coarctation: comparison with young healthy volunteers. Int J Cardiovasc Imaging 2015; 31:823-30. [DOI: 10.1007/s10554-015-0604-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 01/27/2015] [Indexed: 11/24/2022]
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In vivo and in vitro validation of aortic flow quantification by time-resolved three-dimensional velocity-encoded MRI. Int J Cardiovasc Imaging 2012; 28:1999-2008. [DOI: 10.1007/s10554-012-0027-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 02/01/2012] [Indexed: 10/28/2022]
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Current world literature. Curr Opin Cardiol 2012; 27:682-95. [PMID: 23075824 DOI: 10.1097/hco.0b013e32835a0ad8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Rengier F, Delles M, Unterhinninghofen R, Ley S, Partovi S, Dillmann R, Kauczor HU, von Tengg-Kobligk H. Impact of an aortic nitinol stent graft on flow measurements by time-resolved three-dimensional velocity-encoded MRI. Acad Radiol 2012; 19:274-80. [PMID: 22177284 DOI: 10.1016/j.acra.2011.10.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 10/18/2011] [Accepted: 10/24/2011] [Indexed: 11/26/2022]
Abstract
RATIONALE AND OBJECTIVES Three-dimensional (3D) velocity-encoded cine (VEC) magnetic resonance imaging (MRI) has the potential to quantify 3D hemodynamic aspects known from computational fluid dynamics and to be used to identify hemodynamic risk factors for complications of endovascular aortic repair. The purpose of this study was to investigate the impact of an aortic nickel-titanium (nitinol) stent graft on the accuracy of flow measurements by 3D VEC MRI. MATERIALS AND METHODS A pump generated pulsatile aortic flow in an elastic tube phantom mimicking the aorta. Stacked two-dimensional three-directional VEC MRI (stacked-2D-3dir-MRI), 3D three-directional VEC MRI (3D-3dir-MRI), and gold-standard 2D through-plane VEC MRI were applied before and after the insertion of an aortic nitinol stent graft. Six equidistant levels were analyzed twice by the same reader. The percentage difference of the measured flow rate from the gold standard was defined as the parameter of accuracy. RESULTS The overall accuracy of in-stent flow measurements related to the gold standard was -5.4% for stacked-2D-3dir-MRI and -4.1% for 3D-3dir-MRI, demonstrating significant overall underestimation compared to the gold standard (P = .016 and P = .013). However, flow measurements with the stent graft were significantly overestimated by 4.1% using stacked-2D-3dir-MRI (P < .001) and by 5.4% using 3D-3dir-MRI (P = .003) compared to identical measurements without the stent graft. In stacked-2D-3dir-MRI, this positive bias was significantly greater at the proximal and distal ends of the stent graft (P = .025). In 3D-3dir-MRI, measurements along the whole length of the stent graft were affected (P = .006). Intraobserver agreement was excellent, with intraclass correlation coefficients of 0.94 for stacked-2D-3dir-MRI (P < .001) and 0.90 for 3D-3dir-MRI (P < .001). CONCLUSIONS Flow measurements within an aortic nitinol stent graft by 3D VEC MRI are feasible, but stent grafts may cause a significant positive bias.
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