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Kilbride BF, Narsinh KH, Jordan CD, Mueller K, Moore T, Martin AJ, Wilson MW, Hetts SW. MRI-guided endovascular intervention: current methods and future potential. Expert Rev Med Devices 2022; 19:763-778. [PMID: 36373162 PMCID: PMC9869980 DOI: 10.1080/17434440.2022.2141110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 10/25/2022] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Image-guided endovascular interventions, performed using the insertion and navigation of catheters through the vasculature, have been increasing in number over the years, as minimally invasive procedures continue to replace invasive surgical procedures. Such endovascular interventions are almost exclusively performed under x-ray fluoroscopy, which has the best spatial and temporal resolution of all clinical imaging modalities. Magnetic resonance imaging (MRI) offers unique advantages and could be an attractive alternative to conventional x-ray guidance, but also brings with it distinctive challenges. AREAS COVERED In this review, the benefits and limitations of MRI-guided endovascular interventions are addressed, systems and devices for guiding such interventions are summarized, and clinical applications are discussed. EXPERT OPINION MRI-guided endovascular interventions are still relatively new to the interventional radiology field, since significant technical hurdles remain to justify significant costs and demonstrate safety, design, and robustness. Clinical applications of MRI-guided interventions are promising but their full potential may not be realized until proper tools designed to function in the MRI environment are available. Translational research and further preclinical studies are needed before MRI-guided interventions will be practical in a clinical interventional setting.
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Affiliation(s)
- Bridget F. Kilbride
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Kazim H. Narsinh
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | | | | | - Teri Moore
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Alastair J. Martin
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Mark W. Wilson
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Steven W. Hetts
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
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Haochen W, Yinghua Z, Jian W. Intrahepatic arterial localizer guided transjugular intrahepatic portosystemic shunt placement: Feasibility, efficacy, and technical success assessed by a case series-a STROBE- compliant article. Medicine (Baltimore) 2019; 98:e16868. [PMID: 31415422 PMCID: PMC6831380 DOI: 10.1097/md.0000000000016868] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Transjugular intra-hepatic portosystemic shunts (TIPS) had been considered a standard procedure in patients suffering from portal hypertension. The most challenging step in TIPS placement is blind puncture of the portal vein. We had established a localization method by introducing an Intra-Hepatic Arterial based puncture directing Localizer (IHAL) with the assistance of the enhanced computed tomography (CT) reconstruction. This study aimed to evaluate the feasibility, efficacy, and technical success of this method.From June 2018 to August 2018, 10 consecutive patients suffering from refractory ascites or esophageal gastric bleeding by liver cirrhosis were included in this retrospective study to evaluate feasibility, efficacy, and technical success of enhanced CT assisted IHAL-guided puncture of the portal vein. As a control, 10 patients receiving TIPS placement before Jun 2018 with cone beam CT (CBCT)-guided puncture were included to compare the reduction of portal-systemic pressure gradient (PSPG), portal entry time (PET), the number of puncture, dose area product (DAP) and contrast medium consumption.Technical success was 100% in the study group (IHAL-guided group) and in 90.0% of the control group (CBCT-guided group). Appropriate IHAL point could be achieved in all patients under the enhanced CT reconstruction assistance. The median number of punctures and DAP in IHAL group were significantly less than those in CBCT group. The reduction of PSPG, PET, and contrast medium consumption in IHAL group showed no significant differences than those in CBCT group.Enhanced CT reconstruction assisted IHAL-guided portal vein puncture is technically feasible and a reliable tool for TIPS placement resulting in a significant reduction of the number of punctures and DAP.
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Madoff DC, Gaba RC, Weber CN, Clark TWI, Saad WE. Portal Venous Interventions: State of the Art. Radiology 2016; 278:333-53. [PMID: 26789601 DOI: 10.1148/radiol.2015141858] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In recent decades, there have been numerous advances in the management of liver cancer, cirrhosis, and diabetes mellitus. Although these diseases are wide ranging in their clinical manifestations, each can potentially be treated by exploiting the blood flow dynamics within the portal venous system, and in some cases, adding cellular therapies. To aid in the management of these disease states, minimally invasive transcatheter portal venous interventions have been developed to improve the safety of major hepatic resection, to reduce the untoward effects of sequelae from end-stage liver disease, and to minimize the requirement of exogenously administered insulin for patients with diabetes mellitus. This state of the art review therefore provides an overview of the most recent data and strategies for utilization of preoperative portal vein embolization, transjugular intrahepatic portosystemic shunt placement, balloon retrograde transvenous obliteration, and islet cell transplantation.
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Affiliation(s)
- David C Madoff
- From the Department of Radiology, Division of Interventional Radiology, New York-Presbyterian Hospital/Weill Cornell Medical Center, 525 E 68th St, P-518, New York, NY 10065 (D.C.M.); Department of Radiology, Interventional Radiology Section, University of Illinois Hospital, Chicago, Ill (R.C.G.); Department of Radiology, University of Pennsylvania School of Medicine, Penn Presbyterian Medical Center, Philadelphia, Pa (C.N.W., T.W.I.C.); and Department of Radiology, Division of Vascular and Interventional Radiology, University of Michigan Medical Center, Ann Arbor, Mich (W.E.S.)
| | - Ron C Gaba
- From the Department of Radiology, Division of Interventional Radiology, New York-Presbyterian Hospital/Weill Cornell Medical Center, 525 E 68th St, P-518, New York, NY 10065 (D.C.M.); Department of Radiology, Interventional Radiology Section, University of Illinois Hospital, Chicago, Ill (R.C.G.); Department of Radiology, University of Pennsylvania School of Medicine, Penn Presbyterian Medical Center, Philadelphia, Pa (C.N.W., T.W.I.C.); and Department of Radiology, Division of Vascular and Interventional Radiology, University of Michigan Medical Center, Ann Arbor, Mich (W.E.S.)
| | - Charles N Weber
- From the Department of Radiology, Division of Interventional Radiology, New York-Presbyterian Hospital/Weill Cornell Medical Center, 525 E 68th St, P-518, New York, NY 10065 (D.C.M.); Department of Radiology, Interventional Radiology Section, University of Illinois Hospital, Chicago, Ill (R.C.G.); Department of Radiology, University of Pennsylvania School of Medicine, Penn Presbyterian Medical Center, Philadelphia, Pa (C.N.W., T.W.I.C.); and Department of Radiology, Division of Vascular and Interventional Radiology, University of Michigan Medical Center, Ann Arbor, Mich (W.E.S.)
| | - Timothy W I Clark
- From the Department of Radiology, Division of Interventional Radiology, New York-Presbyterian Hospital/Weill Cornell Medical Center, 525 E 68th St, P-518, New York, NY 10065 (D.C.M.); Department of Radiology, Interventional Radiology Section, University of Illinois Hospital, Chicago, Ill (R.C.G.); Department of Radiology, University of Pennsylvania School of Medicine, Penn Presbyterian Medical Center, Philadelphia, Pa (C.N.W., T.W.I.C.); and Department of Radiology, Division of Vascular and Interventional Radiology, University of Michigan Medical Center, Ann Arbor, Mich (W.E.S.)
| | - Wael E Saad
- From the Department of Radiology, Division of Interventional Radiology, New York-Presbyterian Hospital/Weill Cornell Medical Center, 525 E 68th St, P-518, New York, NY 10065 (D.C.M.); Department of Radiology, Interventional Radiology Section, University of Illinois Hospital, Chicago, Ill (R.C.G.); Department of Radiology, University of Pennsylvania School of Medicine, Penn Presbyterian Medical Center, Philadelphia, Pa (C.N.W., T.W.I.C.); and Department of Radiology, Division of Vascular and Interventional Radiology, University of Michigan Medical Center, Ann Arbor, Mich (W.E.S.)
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Three-dimensional C-arm CT-guided transjugular intrahepatic portosystemic shunt placement: Feasibility, technical success and procedural time. Eur Radiol 2016; 26:4277-4283. [PMID: 27048535 DOI: 10.1007/s00330-016-4340-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 02/07/2023]
Abstract
OBJECTIVES Establishment of transjugular intrahepatic portosystemic shunts (TIPS) constitutes a standard procedure in patients suffering from portal hypertension. The most difficult step in TIPS placement is blind puncture of the portal vein. This study aimed to evaluate three-dimensional mapping of portal vein branches and targeted puncture of the portal vein. METHODS Twelve consecutive patients suffering from refractory ascites by liver cirrhosis were included in this retrospective study to evaluate feasibility, technical success and procedural time of C-arm CT-targeted puncture of the portal vein. As a control, 22 patients receiving TIPS placement with fluoroscopy-guided blind puncture were included to compare procedural time. RESULTS Technical success could be obtained in 100 % of the study group (targeted puncture) and in 95.5 % of the control group (blind puncture). Appropriate, three-dimensional C-arm CT-guided mapping of the portal vein branches could be achieved in all patients. The median number of punctures in the C-arm CT-guided study group was 2 ± 1.3 punctures. Procedural time was significantly lower in the study group (14.8 ± 8.2 min) compared to the control group (32.6 ± 22.7 min) (p = 0.02). CONCLUSIONS C-arm CT-guided portal vein mapping is technically feasible and a promising tool for TIPS placement resulting in a significant reduction of procedural time. KEY POINTS • C-arm CT-mapping of the portal vein for 3D TIPS guidance is feasible. • Targeted punctures of the portal vein by C-arm CT reduce procedural time. • A decreased number of punctures could improve patient safety.
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Farsad K, Kaufman JA. Novel Image Guidance Techniques for Portal Vein Targeting During Transjugular Intrahepatic Portosystemic Shunt Creation. Tech Vasc Interv Radiol 2016; 19:10-20. [PMID: 26997085 DOI: 10.1053/j.tvir.2016.01.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The most challenging part of transjugular intrahepatic portosystemic shunt creation is arguably the transvenous access from the hepatic vein to the portal vein. As experience and technology have evolved, the image guidance aspect of this critical step in the procedure has become more robust. Improved means to target the portal vein include both direct and indirect methods of portal vein opacification, cross-sectional imaging for both targeting and access, and novel use of transabdominal and intravascular ultrasound guidance. These techniques are described herein.
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Affiliation(s)
- Khashayar Farsad
- Dotter Interventional Institute, Oregon Health and Science University, Portland, OR.
| | - John A Kaufman
- Dotter Interventional Institute, Oregon Health and Science University, Portland, OR
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Magnetic Resonance-Guided Passive Catheter Tracking for Endovascular Therapy. Magn Reson Imaging Clin N Am 2015; 23:591-605. [PMID: 26499277 DOI: 10.1016/j.mric.2015.05.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of MR guidance for endovascular intervention is appealing because of its lack of ionizing radiation, high-contrast visualization of vessel walls and adjacent soft tissues, multiplanar capabilities, and potential to incorporate functional information such as flow, fluid dynamics, perfusion, and cardiac motion. This review highlights state-of-the-art imaging techniques and hardware used for passive tracking of endovascular devices in interventional MR imaging, including negative contrast, passive contrast, nonproton multispectral, and direct current techniques. The advantages and disadvantages of passive tracking relative to active tracking are also summarized.
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Tsauo J, Luo X, Ye L, Li X. Three-Dimensional Path Planning Software-Assisted Transjugular Intrahepatic Portosystemic Shunt: A Technical Modification. Cardiovasc Intervent Radiol 2014; 38:742-6. [DOI: 10.1007/s00270-014-0931-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Accepted: 05/03/2014] [Indexed: 11/29/2022]
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Transjugular intrahepatic portosystemic shunt creation using intravascular ultrasound guidance. J Vasc Interv Radiol 2012; 23:1594-602. [PMID: 23099001 DOI: 10.1016/j.jvir.2012.08.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 08/08/2012] [Accepted: 08/13/2012] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To describe the use of intravascular ultrasound (US) guidance for creation of transjugular intrahepatic portosystemic shunts (TIPSs) in humans. MATERIALS AND METHODS The initial 25 cases of intravascular US-guided TIPS were retrospectively compared versus the last 75 conventional TIPS cases during the same time period at the same institution in terms of the number of needle passes required to establish portal vein (PV) access, fluoroscopy time, and needle pass-related complications. RESULTS Intravascular US-guided TIPS creation was successful in all cases, and there was no statistically significant difference in number of needle passes, fluoroscopy time, or needle pass-related complications between TIPS techniques. Intravascular US-guided TIPS creation was successful in cases in which conventional TIPS creation had failed as a result of PV thrombosis or distorted anatomy. Intravascular US guidance for TIPS creation was additionally useful in a patient with Budd-Chiari syndrome and in a patient with intrahepatic tumors. CONCLUSIONS Intravascular US is a safe and reproducible means of real-time image guidance for TIPS creation, equivalent in efficacy to conventional fluoroscopic guidance. Real-time sonographic guidance with intravascular US may prove advantageous for cases in which there is PV thrombus, distorted anatomy, Budd-Chiari syndrome, or hepatic tumors.
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Saikus CE, Ratnayaka K, Barbash IM, Colyer JH, Kocaturk O, Faranesh AZ, Lederman RJ. MRI-guided vascular access with an active visualization needle. J Magn Reson Imaging 2011; 34:1159-66. [PMID: 22006552 PMCID: PMC3201741 DOI: 10.1002/jmri.22715] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To develop an approach to vascular access under magnetic resonance imaging (MRI), as a component of comprehensive MRI-guided cardiovascular catheterization and intervention. MATERIALS AND METHODS We attempted jugular vein access in healthy pigs as a model of "difficult" vascular access. Procedures were performed under real-time MRI guidance using reduced field of view imaging. We developed an "active" MRI antenna-needle having an open-lumen, distinct tip appearance and indicators of depth and trajectory in order to enhance MRI visibility during the procedure. We compared performance of the active needle against an unmodified commercial passively visualized needle, measured by procedure success among operators with different levels of experience. RESULTS MRI-guided central vein access was feasible using both the active needle and the unmodified passive needle. The active needle required less time (88 vs. 244 sec, P = 0.022) and fewer needle passes (4.5 vs. 9.1, P = 0.028), irrespective of operator experience. CONCLUSION MRI-guided access to central veins is feasible in our animal model. When image guidance is necessary for vascular access, performing this component under MRI will allow wholly MRI-guided catheterization procedures that do not require adjunctive imaging facilities such as x-ray or ultrasound. The active needle design showed enhanced visibility, as expected. These capabilities may permit more complex catheter-based cardiovascular interventional procedures enabled by enhanced image guidance.
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Affiliation(s)
- Christina E Saikus
- Cardiovascular and Pulmonary Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-1061, USA
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Abstract
Surgical and interventional instruments as well as implants can cause significant magnetic resonance image (MRI) artifacts. The artifacts can be used to visualize instruments, cannulae, guide wires, catheters during interventional MRI and Nitinol devices have proven to be useful for MRI procedures. Diagnostic imaging is often compromised in the area of an implant. Complete vanishing of signals occurs in close proximity or inside implants. The paper presents a fundamental evaluation of MRI artifact of Nitinol devices such as Stents, Vena Cava Filter, heart defect closure devices, cannulae, guide wire, localizer, anastomosis device, etc. in a 1.0 Tesla magnetic field. The American Society for Testing Materials (ASTM) recommendations for selection of sequences and test setup were used but the results of this paper are not sufficient for FDA approval.
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Piliere G, Van Horn MH, Dixon R, Stavas J, Aylward S, Bullitt E. Vessel target location estimation during the TIPS procedure. Med Image Anal 2009; 13:519-29. [PMID: 19332378 DOI: 10.1016/j.media.2009.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Revised: 02/20/2009] [Accepted: 02/24/2009] [Indexed: 01/01/2023]
Abstract
Creation of a transjugular intrahepatic portosystemic shunt (TIPS) requires passage of a needle toward a moving target that is only seen transiently by X-ray prior to needle passage. Intraoperative, 3D target localization would facilitate target access and improve the safety of the procedure. The clinical assumption is that patients undergoing the TIPS procedure possess rigid, cirrhotic livers that undergo only intraoperative translation without significant deformation or rotation. Based upon this assumption, we hypothesize that the position of any unseen, 3D target point within the liver can be determined intraoperatively by precalculation of the relative positions of the target point to a different 3D point that can be tracked intraoperatively. This paper examines this hypothesis using intraoperatively acquired, biplane, X-ray images of seven patients. In six, we tracked the effects of cardiac and respiratory motion, and in three the effects of needle pressure. Methods involved reconstruction of 3D vessel bifurcation and other trackable intrahepatic points from biplane angiograms, measurement of liver deformation by examining changing distances between these 3D points over time, and comparison of expected to actual displacements of these points with respect to a fixed reference point in the liver. We conclude that, for the rigid livers associated with patients undergoing TIPS, that there is less intraoperative deformation than previously reported by other groups addressing healthy liver deformation, and that the location of an unseen target can be predicted within 3mm accuracy.
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Affiliation(s)
- Guillaume Piliere
- CASILab, Division of Neurosurgery, University of North Carolina-CH, Chapel Hill, NC 27599, USA
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Ratnayaka K, Faranesh AZ, Guttman MA, Kocaturk O, Saikus CE, Lederman RJ. Interventional cardiovascular magnetic resonance: still tantalizing. J Cardiovasc Magn Reson 2008; 10:62. [PMID: 19114017 PMCID: PMC2637847 DOI: 10.1186/1532-429x-10-62] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 12/29/2008] [Indexed: 12/30/2022] Open
Abstract
The often touted advantages of MR guidance remain largely unrealized for cardiovascular interventional procedures in patients. Many procedures have been simulated in animal models. We argue these opportunities for clinical interventional MR will be met in the near future. This paper reviews technical and clinical considerations and offers advice on how to implement a clinical-grade interventional cardiovascular MR (iCMR) laboratory. We caution that this reflects our personal view of the "state of the art."
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Affiliation(s)
- Kanishka Ratnayaka
- Translational Medicine Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
- Cardiology Division, Children's National Medical Center, Washington, DC, USA
| | - Anthony Z Faranesh
- Translational Medicine Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael A Guttman
- Translational Medicine Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Ozgur Kocaturk
- Translational Medicine Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Christina E Saikus
- Translational Medicine Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Robert J Lederman
- Translational Medicine Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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Kos S, Huegli R, Bongartz GM, Jacob AL, Bilecen D. MR-guided endovascular interventions: a comprehensive review on techniques and applications. Eur Radiol 2007; 18:645-57. [PMID: 18071710 DOI: 10.1007/s00330-007-0818-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2007] [Revised: 10/01/2007] [Accepted: 10/30/2007] [Indexed: 10/22/2022]
Abstract
The magnetic resonance (MR) guidance of endovascular interventions is probably one of the greatest challenges of clinical MR research. MR angiography is not only an imaging tool for the vasculature but can also simultaneously depict high tissue contrast, including the differentiation of the vascular wall and perivascular tissues, as well as vascular function. Several hurdles had to be overcome to allow MR guidance for endovascular interventions. MR hardware and sequence design had to be developed to achieve acceptable patient access and to allow real-time or near real-time imaging. The development of interventional devices, both applicable and safe for MR imaging (MRI), was also mandatory. The subject of this review is to summarize the latest developments in real-time MRI hardware, MRI, visualization tools, interventional devices, endovascular tracking techniques, actual applications and safety issues.
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Affiliation(s)
- Sebastian Kos
- Institute of Radiology, Division of Interventional Radiology, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland.
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Levy EB, Tang J, Lindisch D, Glossop N, Banovac F, Cleary K. Implementation of an electromagnetic tracking system for accurate intrahepatic puncture needle guidance: accuracy results in an in vitro model. Acad Radiol 2007; 14:344-54. [PMID: 17307668 DOI: 10.1016/j.acra.2006.12.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 11/13/2006] [Accepted: 12/08/2006] [Indexed: 11/24/2022]
Abstract
RATIONALE AND OBJECTIVES Electromagnetic tracking potentially may be used to guide percutaneous needle-based interventional procedures. The accuracy of electromagnetic guided-needle puncture procedures has not been specifically characterized. This article reports the functional accuracy of a needle guidance system featuring real-time tracking of respiratory-related target motion. MATERIALS AND METHODS A needle puncture algorithm based on a "free-hand" needle puncture technique for percutaneous intrahepatic portocaval systemic shunt was employed. Preoperatively obtained computed tomographic images were displayed on a graphical user interface and registered with the electromagnetically tracked needle position. The system and procedure was tested on an abdominal torso phantom containing a liver model mounted on a motor-driven platform to simulate respiratory excursion. The liver model featured two hollow tubes to simulate intrahepatic vessels. Registration and respiratory motion tracking was performed using four skin fiducials and a needle fiducial within the liver. Success rates for 15 attempts at simultaneous puncture of the two "vessels" of different luminal diameters guided by the electromagnetic tracking system were recorded. RESULTS Successful "vessel" puncture occurred in 0%, 33%, and 53% of attempts for 3-, 5-, and 7-mm diameter "vessels," respectively. Using a two-dimensional accuracy prediction analysis, predicted accuracy exceeded actual puncture accuracy by 25%-35% for all vessel diameters. Accuracy outcome improved when depth-only errors were omitted from the analysis. CONCLUSIONS Actual puncture success rate approximates predicted rates for target vessels 5 mm in diameter or greater when depth errors are excluded. Greater accuracy for smaller diameter vessels would be desirable for implementation in a broader range of clinical applications.
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Affiliation(s)
- Elliot B Levy
- Department of Radiology, Section of Interventional Radiology, Medstar-Georgetown University Hospital, 3800 Reservoir Road, NW, Washington, DC 20007, USA.
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Brzozowski L, Ganguly A, Pop M, Wen Z, Bennett R, Fahrig R, Rowlands JA. Compatibility of interventional x-ray and magnetic resonance imaging: feasibility of a closed bore XMR (CBXMR) system. Med Phys 2006; 33:3033-45. [PMID: 16964881 DOI: 10.1118/1.2219328] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
A next-generation interventional guidance system is proposed that will enable intraprocedural access to both x-ray and magnetic resonance imaging (MRI) modalities. This closed bore XMR (CBXMR) system is comprised of a conventional radiographic rotating anode x-ray tube and a direct conversion flat panel detector on a rotating gantry positioned adjacent to the bore of a 1.5 T MRI. To assess the feasibility of such a system, we have investigated the degree of compatibility between the x-ray components and the MRI. For /-->B(ext)/ < 200 G the effect on the radiographic tube motor was negligible regardless of the orientation of -->B(ext) with respect to the motor axis of rotation--the frequency of anode rotation remained within 6% of the 3400 rpm frequency measured at 0 G. For /-->B(ext)/ >2400 G the anode slowed down to below 2400 rpm at all orientations. At intermediate B(ext), the frequency of rotation varied between 2400 and 3200 rpm, showing a strong dependence on orientation, with -->B(ext) perpendicular to the tube axis having a much stronger effect on the rotation frequency than -->B(ext) parallel to the tube axis. In contrast to the effect of -->B(ext) on the induction motor, parallel -->B(ext) had a stronger detrimental effect on the cathode-anode electron beam, whose path was at 16 degrees to the tube axis, than the perpendicular -->B(ext). Parallel -->B(ext) of several hundred Gauss had a defocusing effect on the x-ray focal spot. -->B(ext) perpendicular to the electron beam shifted the beam without significant defocusing. We have determined that the direct conversion flat panel detector (FPD) technology is not intrinsically sensitive to -->B(ext), and that the modifications required to make the proposed FPDs MRI compatible are minimal. The homogeneity of the MRI signal in the normal field of view was not significantly degraded by the presence of these x-ray components in the vicinity of the MRI bore entrance.
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Affiliation(s)
- Lukasz Brzozowski
- Department of Medical Biophysics, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada
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Arepally A, Karmarkar PV, Qian D, Barnett B, Atalar E. Evaluation of MR/Fluoroscopy–guided Portosystemic Shunt Creation in a Swine Model. J Vasc Interv Radiol 2006; 17:1165-73. [PMID: 16868170 DOI: 10.1097/01.rvi.0000228493.07075.fc] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To evaluate three different percutaneous portosystemic shunts created with magnetic resonance (MR) imaging and fluoroscopy guidance in a swine model. MATERIALS AND METHODS In stage 1 of the experiment, an active MR intravascular needle system was created for needle tracking and extracaval punctures. Twenty inferior vena cava (IVC)/superior mesenteric vein (SMV)/portal vein (PV) punctures were performed in 10 swine (weight, 40-45 kg) in a 1.5-T short-bore interventional MR imager. With use of a real-time MR imaging sequence, the needle was guided through the IVC and into the SMV or PV (N = 20 punctures). After confirmation, a wire was advanced into the portal venous system under MR imaging guidance (N = 20). In stage 2, animals were transferred to the radiographic fluoroscopy suite for deployment of shunts. Three different shunts were evaluated in this study: (i) a commercial stent-graft, (ii) a prototype bridging stent, and (iii) a prototype nitinol vascular anastomotic device. Postprocedural necropsy was performed in all animals. RESULTS Successful MR-guided IVC/SMV punctures were performed in all 20 procedures (100%). All three shunts were deployed. Stent-grafts had the poorest mechanism for securing a shunt. The vascular anastomotic device and the bridging stent had more secure anchoring mechanisms but also had higher technical failure rates (50% and 40%, respectively). When deployed successfully, the vascular anastomotic device resulted in no bleeding at the sites of punctures at necropsy. CONCLUSION Percutaneous shunts and vascular anastomoses between the portal mesenteric venous system and IVC were successfully created with use of a combination of MR imaging and conventional fluoroscopy for guidance.
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Affiliation(s)
- Aravind Arepally
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins Medical Institutions, Blalock 545, 600 North Wolfe Street, Baltimore, MD 21287, USA.
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17
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Raval AN, Karmarkar PV, Guttman MA, Ozturk C, DeSilva R, Aviles RJ, Wright VJ, Schenke WH, Atalar E, McVeigh ER, Lederman RJ. Real-time MRI guided atrial septal puncture and balloon septostomy in swine. Catheter Cardiovasc Interv 2006; 67:637-43. [PMID: 16532499 PMCID: PMC1463249 DOI: 10.1002/ccd.20579] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cardiac perforation during atrial septal puncture (ASP) might be avoided by improved image guidance. X-ray fluoroscopy (XRF), which guides ASP, visualizes tissue poorly and does not convey depth information. Ultrasound is limited by device shadows and constrained imaging windows. Alternatively, real-time MRI (rtMRI) provides excellent tissue contrast in any orientation and may enable ASP and balloon atrial septostomy (BAS) in swine. Custom MRI catheters incorporated "active" (receiver antenna) and "passive" (iron or gadolinium) elements. Wholly rtMRI-guided transfemoral ASP and BAS were performed in 10 swine in a 1.5T interventional suite. Hemodynamic results were measured with catheters and velocity encoded MRI. Successful ASP was performed in all 10 animals. Necropsy confirmed septostomy confined within the fossa ovalis in all. BAS was successful in 9/10 animals. Antenna failure in a re-used needle led to inadvertent vena cava tear prior to BAS in 1 animal. ASP in the same animal was easily performed using a new needle. rtMRI illustrated clear device-tissue-lumen relationships in multiple orientations, and facilitated simple ASP and BAS. The mean procedure time was 19 +/- 10 minutes. Septostomy achieved a mean left to right shunt ratio of 1.3:1 in these healthy animals. Interactive rtMRI permits rapid transcatheter ASP and BAS in swine. Further technical development may enable novel applications.
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Affiliation(s)
- Amish N. Raval
- From the Cardiovascular Branch (ANR, PVK, CO, RDS, RJA, VJW, WHS, RJL) and the
| | - Parag V. Karmarkar
- From the Cardiovascular Branch (ANR, PVK, CO, RDS, RJA, VJW, WHS, RJL) and the
- Department of Radiology, The Johns Hopkins University, Baltimore, MD, USA
| | - Michael A. Guttman
- Laboratory of Cardiac Energetics (MAG, ERM), Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA; and
| | - Cengizhan Ozturk
- From the Cardiovascular Branch (ANR, PVK, CO, RDS, RJA, VJW, WHS, RJL) and the
| | - Ranil DeSilva
- From the Cardiovascular Branch (ANR, PVK, CO, RDS, RJA, VJW, WHS, RJL) and the
| | - Ronnier J. Aviles
- From the Cardiovascular Branch (ANR, PVK, CO, RDS, RJA, VJW, WHS, RJL) and the
| | - Victor J. Wright
- From the Cardiovascular Branch (ANR, PVK, CO, RDS, RJA, VJW, WHS, RJL) and the
| | - William H. Schenke
- From the Cardiovascular Branch (ANR, PVK, CO, RDS, RJA, VJW, WHS, RJL) and the
| | - Ergin Atalar
- Department of Radiology, The Johns Hopkins University, Baltimore, MD, USA
| | - Elliot R. McVeigh
- Laboratory of Cardiac Energetics (MAG, ERM), Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA; and
| | - Robert J. Lederman
- From the Cardiovascular Branch (ANR, PVK, CO, RDS, RJA, VJW, WHS, RJL) and the
- Address for Correspondence: Robert J. Lederman, MD, Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10, Room 2c713, MSC 1538, Bethesda, MD 20892-1538, USA. Telephone: 1-301-402-6769.
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18
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Abstract
Dynamic changes in cardiac structure and function are usually examined by real-time imaging techniques such as angiography or echocardiography. MRI has many advantages compared with these established cardiac imaging modalities. However, system hardware and software limitations have limited cardiac MRI to gated acquisitions that are lengthy and often result in failed acquisitions and examinations. Recently, MRI has evolved into a technique capable of imaging dynamic processes in real time. Improvements in hardware, pulse sequences, and image reconstruction algorithms have enabled real-time cardiac MRI with high spatial resolution, high temporal resolution, and various types of image contrast without requiring cardiac gating or breath-holding. This article provides an overview of current capability and highlights key technical and clinical advances. The future prospects of real-time cardiac MRI will depend on 1) the development of techniques that further improve signal to noise ratio, contrast, spatial resolution, and temporal resolution, without introducing artifacts; 2) the development of software infrastructure that facilitates rapid interactive examination; and 3) the development and validation of several new clinical assessments.
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Affiliation(s)
- Krishna S Nayak
- Electrical Engineering-Systems, 3740 McClintock Avenue, EEB 406, University of Southern California, Los Angeles, CA 90089-2564, USA.
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19
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Affiliation(s)
- Robert J Lederman
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1538, USA.
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20
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Raval AN, Karmarkar PV, Guttman MA, Ozturk C, Sampath S, DeSilva R, Aviles RJ, Xu M, Wright VJ, Schenke WH, Kocaturk O, Dick AJ, Raman VK, Atalar E, McVeigh ER, Lederman RJ. Real-time magnetic resonance imaging-guided endovascular recanalization of chronic total arterial occlusion in a swine model. Circulation 2006; 113:1101-7. [PMID: 16490819 PMCID: PMC1428785 DOI: 10.1161/circulationaha.105.586727] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Endovascular recanalization (guidewire traversal) of peripheral artery chronic total occlusion (CTO) can be challenging. X-ray angiography resolves CTO poorly. Virtually "blind" device advancement during x-ray-guided interventions can lead to procedure failure, perforation, and hemorrhage. Alternatively, MRI may delineate the artery within the occluded segment to enhance procedural safety and success. We hypothesized that real-time MRI (rtMRI)-guided CTO recanalization can be accomplished in an animal model. METHODS AND RESULTS Carotid artery CTO was created by balloon injury in 19 lipid-overfed swine. After 6 to 8 weeks, 2 underwent direct necropsy analysis for histology, 3 underwent primary x-ray-guided CTO recanalization attempts, and the remaining 14 underwent rtMRI-guided recanalization attempts in a 1.5-T interventional MRI system. Real-time MRI intervention used custom CTO catheters and guidewires that incorporated MRI receiver antennae to enhance device visibility. The mean length of the occluded segments was 13.3+/-1.6 cm. The rtMRI-guided CTO recanalization was successful in 11 of 14 swine and in only 1 of 3 swine with the use of x-ray alone. After unsuccessful rtMRI (n=3), x-ray-guided attempts were also unsuccessful. CONCLUSIONS Recanalization of long CTO is entirely feasible with the use of rtMRI guidance. Low-profile clinical-grade devices will be required to translate this experience to humans.
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Affiliation(s)
- Amish N Raval
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1538, USA
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21
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Wacker FK, Hillenbrand CM, Duerk JL, Lewin JS. MR-guided endovascular interventions: device visualization, tracking, navigation, clinical applications, and safety aspects. Magn Reson Imaging Clin N Am 2005; 13:431-9. [PMID: 16084411 DOI: 10.1016/j.mric.2005.04.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Reliable visualization and tracking are essential for guiding endovascular devices within blood vessels. The most commonly used methods are susceptibility artifact-based tracking that relies on the artifact created within the image by the device and microcoil- or antenna-based tracking that uses the high signal generated by small MR endovascular receive coils when the transmit coil emits a nonselective radiofrequency pulse. To date, the use of endovascular MR guidance techniques has primarily been confined to animal experiments. There are only a few reports on MR-guided endovascular applications in patients. Therefore, access to the patient within the scanner, dedicated devices, and safety issues remain major challenges. To face these challenges, attention from all radiologists, especially interventional radiologists, is required to make MR-guided endovascular procedures a clinical reality.
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Affiliation(s)
- Frank K Wacker
- Department of Radiology, Klinik und Hochschulambulanz für Radiologie und Nuklearmedizin, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany.
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22
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Sato KT, Larson AC, Rhee TK, Salem RA, Nemcek AA, Mounajjed T, Paunesku T, Woloschak G, Nikolaides P, Omary RA. Real-time MRI monitoring of transcatheter hepatic artery contrast agent delivery in rabbits. Acad Radiol 2005; 12:1342-50. [PMID: 16179211 DOI: 10.1016/j.acra.2005.06.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Revised: 05/26/2005] [Accepted: 06/02/2005] [Indexed: 11/24/2022]
Abstract
RATIONALE AND OBJECTIVES We sought to test the hypothesis that transcatheter hepatic artery delivery of dilute gadolinium (Gd) in rabbits can be monitored in real-time using magnetic resonance imaging (MRI). MATERIALS AND METHODS Catheters (2F) were inserted via a femoral access into the hepatic arteries of six New Zealand White rabbits under radiographic guidance. After transfer to a 1.5-T MRI scanner, 26 separate hepatic artery injections of 2 mL of 4% Gd and 14 sham injections were performed. Real-time imaging of all injections was acquired using two-dimensional projection inversion recovery-gradient echo. Films of these 40 injections, as well as 10 random repeats, were independently reviewed in a randomized, blinded fashion by two Certificate of Added Qualification-certified interventional radiologists. Observers reported (i) if Gd injection occurred and (ii) if so, the location of delivery. For each observer, we compared sensitivity/specificity for real-time visualization of contrast injection and accuracy of injection localization. Interobserver and intraobserver variability was assessed using the kappa statistic. X-ray digital subtraction angiography was the gold standard for all MRI studies. RESULTS Both observers had a sensitivity of 100% and a specificity of 93%. Accuracy for intrahepatic contrast delivery was 77% for both observers. Accuracy for extrahepatic delivery was 92% and 96%, respectively. Both interobserver and intraobserver agreement was outstanding. CONCLUSIONS In rabbits, MRI allows for accurate real-time monitoring of transcatheter hepatic artery delivery of contrast agent. Localization accuracy is higher outside the liver than within the liver. These results can be used as a baseline reference for comparing the accuracy of delivery of Gd-tagged therapies in the future.
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Affiliation(s)
- Kent T Sato
- Department of Radiology, Northwestern University Medical School, Northwestern Memorial Hospital, 251 E. Huron St, 4-710 Feinberg, Chicago, IL 60611,USA.
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23
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Abstract
Magnetic resonance imaging (MRI), which provides superior soft-tissue imaging and no known harmful effects, has the potential as an alternative modality to guide various medical interventions. This review will focus on MR-guided endovascular interventions and present its current state and future outlook. In the first technical part, enabling technologies such as developments in fast imaging, catheter devices, and visualization techniques are examined. This is followed by a clinical survey that includes proof-of-concept procedures in animals and initial experience in human subjects. In preclinical experiments, MRI has already proven to be valuable. For example, MRI has been used to guide and track targeted cell delivery into or around myocardial infarctions, to guide atrial septal puncture, and to guide the connection of portal and systemic venous circulations. Several investigational MR-guided procedures have already been reported in patients, such as MR-guided cardiac catheterization, invasive imaging of peripheral artery atheromata, selective intraarterial MR angiography, and preliminary angioplasty and stent placement. In addition, MR-assisted transjugular intrahepatic portosystemic shunt procedures in patients have been shown in a novel hybrid double-doughnut x-ray/MRI system. Numerous additional investigational human MR-guided endovascular procedures are now underway in several medical centers around the world. There are also significant hurdles: availability of clinical-grade devices, device-related safety issues, challenges to patient monitoring, and acoustic noise during imaging. The potential of endovascular interventional MRI is great because as a single modality, it combines 3-dimensional anatomic imaging, device localization, hemodynamics, tissue composition, and function.
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Affiliation(s)
- Cengizhan Ozturk
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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24
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Raval AN, Telep JD, Guttman MA, Ozturk C, Jones M, Thompson RB, Wright VJ, Schenke WH, DeSilva R, Aviles RJ, Raman VK, Slack MC, Lederman RJ. Real-time magnetic resonance imaging-guided stenting of aortic coarctation with commercially available catheter devices in Swine. Circulation 2005; 112:699-706. [PMID: 16043639 PMCID: PMC1513629 DOI: 10.1161/circulationaha.105.542647] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Real-time MR imaging (rtMRI) is now technically capable of guiding catheter-based cardiovascular interventions. Compared with x-ray, rtMRI offers superior tissue imaging in any orientation without ionizing radiation. Translation to clinical trials has awaited the availability of clinical-grade catheter devices that are both MRI visible and safe. We report a preclinical safety and feasibility study of rtMRI-guided stenting in a porcine model of aortic coarctation using only commercially available catheter devices. METHOD AND RESULTS Coarctation stenting was performed wholly under rtMRI guidance in 13 swine. rtMRI permitted procedure planning, device tracking, and accurate stent deployment. "Active" guidewires, incorporating MRI antennas, improved device visualization compared with unmodified "passive" nitinol guidewires and shortened procedure time (26+/-11 versus 106+/-42 minutes; P=0.008). Follow-up catheterization and necropsy showed accurate stent deployment, durable gradient reduction, and appropriate neointimal formation. MRI immediately identified aortic rupture when oversized devices were tested. CONCLUSIONS This experience demonstrates preclinical safety and feasibility of rtMRI-guided aortic coarctation stenting using commercially available catheter devices. Patients may benefit from rtMRI in the future because of combined device and tissue imaging, freedom from ionizing radiation, and the ability to identify serious complications promptly.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Robert J. Lederman
- Correspondence to Robert J. Lederman, MD, Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bldg 10, Room 2c713, MSC 1538, Bethesda, MD 20892–1538. E-mail
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25
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Kee ST, Ganguly A, Daniel BL, Wen Z, Butts K, Shimikawa A, Pelc NJ, Fahrig R, Dake MD. MR-guided transjugular intrahepatic portosystemic shunt creation with use of a hybrid radiography/MR system. J Vasc Interv Radiol 2005; 16:227-34. [PMID: 15713923 DOI: 10.1097/01.rvi.0000143766.08029.6e] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To evaluate the performance of a combined hybrid radiography/magnetic resonance (MR) unit to guide portal vein (PV) puncture during human transjugular intrahepatic portosystemic shunt (TIPS) creation. MATERIALS AND METHODS Fourteen patients undergoing TIPS creation were studied during standard clinical applications. Patients were anesthetized and then positioned in an open MR unit containing a flat-panel radiographic fluoroscopic unit. With use of a combination of fluoroscopy and MR imaging, the PV was accessed and the TIPS procedure was performed. A noncovered nitinol stent or a covered stent-graft was placed in the TIPS tract. Number of punctures required, total procedure time, fluoroscopy time, procedural success rate, complications, and ultrasonographic and clinical follow-up were recorded. RESULTS Clinical success was obtained in 13 of 14 patients. In one patient, extrahepatic puncture of the PV occurred, resulting in hemorrhage and requiring placement of a covered stent to control the bleeding. The mean number of punctures required to access the PV was 2.6 +/- 1.7, and the total procedure time was 2.5 hours +/- 0.6. Mean fluoroscopy time was 22.3 minutes +/- 5.5. Results of clinical and ultrasonographic follow-up compare favorably to previously published reports. CONCLUSION TIPS creation with a combination hybrid radiography/MR unit is feasible and may reduce the number of needle passes required and radiation exposure, with similar overall outcomes compared with studies reported in the literature.
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Affiliation(s)
- Stephen T Kee
- Department of Radiology, Stanford University, California 94305, USA.
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26
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Saad WEA, Davies MG, Lee DE, Patel NC, Sahler LG, Sasson T, Kitanososno T, Waldman DL. Transjugular Intrahepatic Portosystemic Shunt in a Living Donor Left Lateral Segment Liver Transplant Recipient: Technical Considerations. J Vasc Interv Radiol 2005; 16:873-7. [PMID: 15947053 DOI: 10.1097/01.rvi.0000157776.47580.f7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The technical aspects of placing transjugular intrahepatic portosystemic shunts (TIPS) in liver transplant recipients with full allografts have well been described. In the era of live related hepatic donors, and the growing population of their recipients, it is likely that TIPS shunts will be placed in failing transplant lobes/segments. Growing allografts that are initially undersized can have an unconventional orientation of the hepatic and portal veins, which may also change with remodeling and rotation of the graft during their growth. The authors review the technical differences for TIPS procedures in transplants, particularly split grafts. They describe a technically successful TIPS procedure in an undersized and remodeled left lateral segment liver recipient and the additional difficulty this may pose.
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Affiliation(s)
- Wael E A Saad
- University of Rochester Medical Center, 601 Elmwood Avenue, Box 648, Rochester, NY 14642-8648, USA.
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27
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Abstract
Although x-ray fluoroscopy (XRF) has guided diagnostic and therapeutic transcatheter procedures for decades, certain limitations still exist. XRF still visualizes tissue poorly and relies on projection of shadows that do not convey depth information. Adjunctive echocardiography overcomes some of these limitations but still suffers suboptimal or unreliable imaging windows. Furthermore, ionizing radiation exposure in children imparts a cancer risk. An interventional platform using real-time magnetic resonance imaging (MRI) may offer superior image guidance without radiation. Although there are many remaining challenges, but real-time MRI has the potential to revolutionize transcatheter therapeutics.
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Affiliation(s)
- A N Raval
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Building 10, Room 2c713, MSC 1538, Bethesda, MD 20892-1538, USA
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Wacker FK, Elgort D, Hillenbrand CM, Duerk JL, Lewin JS. The Catheter-Driven MRI Scanner: A New Approach to Intravascular Catheter Tracking and Imaging-Parameter Adjustment for Interventional MRI. AJR Am J Roentgenol 2004; 183:391-5. [PMID: 15269031 DOI: 10.2214/ajr.183.2.1830391] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Our aim was to test the feasibility of a hands-free approach to MRI that allows the interventionalist to track an angiographic catheter in real time throughout the procedure and to automatically change imaging parameters by catheter manipulation. MATERIALS AND METHODS A tracking method that is based on an active device localization was implemented on a 1.5-T MRI scanner. The system determines the current position and orientation of a catheter in 3D space in an endless feedback loop. Automatic scanning plane-adjustment procedures written in the software of the MRI system ensure image acquisition at the location of the catheter tip. The system calculates the device velocity to automatically adjust parameters such as field of view (FOV) and resolution. To evaluate the feasibility and performance in vivo and ex vivo, we performed experiments in two vessel phantoms and on six pigs. RESULTS The system collected the tracking data within 40 msec; an additional 10-20 msec was then required to perform the localization and velocity calculations and to update the image parameters. The system could localize a motionless catheter in the aorta in 100% and a moving catheter in 98% of measured attempts. The system responded in real time to changes in device velocity by dynamically adjusting spatial resolution and FOV in both phantom and porcine trials. Using this technique, we successfully catheterized the renal artery in two pigs. CONCLUSION Active tracking, combined with automatic scanning plane and imaging parameter adjustment, provides an intuitive MRI scanner interface for the guidance of the vascular procedure.
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Affiliation(s)
- Frank K Wacker
- Department of Radiology, Case Western Reserve University, 11100 Euclid Ave., MRI Bolwel B124, Cleveland, OH 44106, USA.
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Olin JW, Kaufman JA, Bluemke DA, Bonow RO, Gerhard MD, Jaff MR, Rubin GD, Hall W. Atherosclerotic Vascular Disease Conference. Circulation 2004; 109:2626-33. [PMID: 15173045 DOI: 10.1161/01.cir.0000128521.02390.72] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Kahn T, Schulz T, Moche M, Prothmann S, Schneider JP. Klinischer Einsatz der interventionellen MRT (iMRT). Z Med Phys 2003; 13:151-6. [PMID: 14562536 DOI: 10.1078/0939-3889-00163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The integration of diagnostic and therapeutic procedures by MRI is based on the combination of excellent morphologic and functional imaging. The spectrum of MR-guided interventions includes biopsies, thermal ablation procedures, vascular applications, and intraoperative MRI. In all these applications, different scientific groups have obtained convincing results in basic developments as well as in clinical use. Interventional MRI (iMRI) is expected to attain an important role in interventional radiology, minimal invasive therapy, and monitoring of surgical procedures.
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Affiliation(s)
- Thomas Kahn
- Klinik und Poliklinik für Diagnostische Radiologie, Universität Leipzig
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32
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Buecker A, Adam GB, Neuerburg JM, Kinzel S, Glowinski A, Schaeffter T, Rasche V, van Vaals JJ, Guenther RW. Simultaneous real-time visualization of the catheter tip and vascular anatomy for MR-guided PTA of iliac arteries in an animal model. J Magn Reson Imaging 2002; 16:201-8. [PMID: 12203769 DOI: 10.1002/jmri.10148] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To examine the feasibility of simultaneous MR real-time active tip tracking and near real-time depiction of the vascular anatomy for percutaneous angioplasty of iliac arteries under MR guidance. MATERIALS AND METHODS Nine surgically created stenoses of external iliac arteries in pigs were dilated with MR-compatible balloon catheters (Cordis, Roden, The Netherlands). These catheters were equipped with a microcoil for active tracking of the catheter tip with an in-plane update rate of 10 positions per second. The procedures were performed on an interventional 1.5 T Gyroscan ACS-NT scanner (Philips, Best, The Netherlands). Real-time calculation of images acquired by radial k-space filling was performed on a specially designed backprojector exploiting the sliding window reconstruction technique (Philips Research Laboratories, Hamburg, Germany). The image update rate was 20 frames per second using a radial gradient-echo technique (TR = 12 msec, TE = 3.3 msec, 300 radials). MR angiography and X-ray digital subtraction angiography on the X-ray system positioned in-line next to the interventional MR system served as control for the angioplasty results. RESULTS Real-time guidance and positioning of the balloon catheters was possible. The actual position of the catheter tip was indicated in the MR images without any time delay for the reconstruction of the anatomical MR images, which were updated with a rate of 20 frames per second. This yielded a combination of a roadmap and fluoroscopy image, in which the catheter position and the anatomical background image both were continuously updated in real time. Six out of nine stenoses were successfully dilated. The effects of the angioplasty could be visualized by the real-time MR technique, as was proven by X-ray digital subtraction angiography. CONCLUSION Active tip tracking simultaneous with MRI of the vascular anatomy-both in real time-is possible with the applied technique, enabling MR-guided percutaneous dilatation (PTA) of iliac arteries.
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Affiliation(s)
- Arno Buecker
- Clinic of Diagnostic Radiology, University of Technology Aachen, Aachen, Germany.
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33
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Abstract
In the setting of MRI-guided endovascular interventions, catheter-directed Gd-enhanced MRA offers many of the same capabilities as conventional x-ray DSA. Local injections permit rapid depiction of blood vessels and help guide interventions. The primary benefit of IA injections is significant reduction of administered contrast-agent dose compared with conventional IV injections. Another major benefit is facilitated background suppression, including that of adjacent vascular beds. As MRI guidance methods improve, catheter-based Gd injections should gain expanded use in clinical practice.
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Affiliation(s)
- Reed A Omary
- Department of Radiology, Northwestern University Medical School, Chicago, IL 60611, USA.
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34
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Kandarpa K. MR Guidance for Interventions. J Vasc Interv Radiol 2002. [DOI: 10.1016/s1051-0443(02)70071-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Hwang KP, Green JD, Li D, Simonetti OP, Resnick SA, Finn JP, Duerk JL, Omary RA. Minimizing contrast agent dose during intraarterial gadolinium-enhanced MR angiography: in vitro assessment. J Magn Reson Imaging 2002; 15:55-61. [PMID: 11793457 DOI: 10.1002/jmri.10027] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To minimize contrast agent dosage for intra-arterial (IA) contrast-enhanced magnetic resonance angiography (CE-MRA) by examining the effects of encoding order (elliptical vs. sequential) and injection duration (100% to 30% of the acquisition time). MATERIALS AND METHODS Catheter-based IA gadolinium (Gd) injections were performed in an arterial flow phantom. Blood flow rates, injection rates, and injection durations were systematically varied. Signal-to-noise (SNR) measurements were obtained in the aorta, renal artery, and common iliac artery. RESULTS No significant SNR losses were observed for any of the vessels with 75% injection duration, or for the aorta and iliac artery with 50% injection duration. Excellent images of all vessels were obtained at 50% injection duration. There was no significant SNR difference between encoding schemes. CONCLUSION Contrast agent dosage can be substantially reduced without loss of SNR by limiting injection to part of the imaging acquisition time.
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Affiliation(s)
- Ken-Pin Hwang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA
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Fahrig R, Butts K, Wen Z, Saunders R, Kee ST, Sze DY, Daniel BL, Laerum F, Pelc NJ. Truly hybrid interventional MR/X-ray system: investigation of in vivo applications. Acad Radiol 2001; 8:1200-7. [PMID: 11770916 DOI: 10.1016/s1076-6332(03)80702-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
RATIONALE AND OBJECTIVES The purpose of this study was to provide in vivo demonstrations of the functionality of a truly hybrid interventional x-ray/magnetic resonance (MR) system. MATERIALS AND METHODS A digital flat-panel x-ray system (1,024(2) array of 200 microm pixels, 30 frames per second) was integrated into an interventional 0.5-T magnet. The hybrid system is capable of MR and x-ray imaging of the same field of view without patient movement. Two intravascular procedures were performed in a 22-kg porcine model: placement of a transjugular intrahepatic portosystemic shunt (TIPS) (x-ray-guided catheterization of the hepatic vein, MR fluoroscopy-guided portal puncture, and x-ray-guided stent placement) and mock chemoembolization (x-ray-guided subselective catheterization of a renal artery branch and MR evaluation of perfused volume). RESULTS The resolution and frame rate of the x-ray fluoroscopy images were sufficient to visualize and place devices, including nitinol guidewires (0.016-0.035-inch diameter) and stents and a 2.3-F catheter. Fifth-order branches of the renal artery could be seen. The quality of both real-time (3.5 frames per second) and standard MR images was not affected by the x-ray system. During MR-guided TIPS placement, the trocar and the portal vein could be easily visualized, allowing successful puncture from hepatic to portal vein. CONCLUSION Switching back and forth between x-ray and MR imaging modalities without requiring movement of the patient was demonstrated. The integrated nature of the system could be especially beneficial when x-ray and MR image guidance are used iteratively.
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Affiliation(s)
- R Fahrig
- Department of Radiology, Stanford University, Calif 94305, USA
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Bücker A, Neuerburg JM, Adam GB, Glowinski A, Schaeffter T, Rasche V, van Vaals JJ, Günther RW. Real-time MR Guidance for inferior vena cava filter placement in an animal model. J Vasc Interv Radiol 2001; 12:753-6. [PMID: 11389228 DOI: 10.1016/s1051-0443(07)61448-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
It was the aim of this study to examine the feasibility of real-time magnetic resonance (MR) imaging for MR-guided placement of inferior vena cava (IVC) filters, which were placed in five pigs via a femoral approach. The introducer sheath and dilator were marked with Dysprosium rings. The procedures were performed under MR guidance with use of a 1.5-T ACS-NT imager. Radial filling of k-space in conjunction with the sliding window reconstruction technique achieved real-time MR imaging with a frame rate of 20 images/sec. Simultaneous real-time visualization of the vascular anatomy and interventional instruments was achieved under real-time conditions and allowed correct placement of IVC filters in all five cases as confirmed by radiographic angiography.
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Affiliation(s)
- A Bücker
- Clinic for Diagnostic Radiology, University of Technology Aachen, Germany.
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38
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Manke C, Nitz WR, Djavidani B, Strotzer M, Lenhart M, Völk M, Feuerbach S, Link J. MR imaging-guided stent placement in iliac arterial stenoses: a feasibility study. Radiology 2001; 219:527-34. [PMID: 11323483 DOI: 10.1148/radiology.219.2.r01ma03527] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To assess the feasibility of magnetic resonance (MR) imaging-guided stent placement in iliac arterial stenoses. MATERIALS AND METHODS Thirteen patients with 14 iliac arterial stenoses were examined prospectively. Angioplasty was performed through a femoral sheath by using a conventional 1.5-T MR imaging system. Stents and catheters were visualized on the basis of their artifacts. Nitinol stents were placed with gradient-echo MR imaging guidance. Angioplasty balloons were inflated with gadolinium-based contrast material. Results were evaluated clinically and with both digital subtraction angiography (DSA) and contrast material-enhanced MR angiography. RESULTS Ten of 13 patients were treated with technical success by using MR imaging-guided intervention alone. Three patients were treated with additional fluoroscopic guidance, because complications (ie, panic attack, subintimal recanalization, and stent misplacement) occurred with MR guidance. The quality of the postinterventional contrast-enhanced MR angiograms of three of 12 lesions with stents was limited owing to stent-induced signal loss of the lumen. The mean stenosis degree after stent placement was significantly higher at contrast-enhanced MR angiography than at DSA (24.6% vs 6.2%). The mean MR imaging-guided procedure time was 74 minutes. CONCLUSION MR imaging-guided stent placement in iliac arteries is feasible in select patients. The presented technique has limitations-that is, long procedure times, lack of real-time monitoring, and stent artifacts-that necessitate further modifications before it can be recommended for clinical use.
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Affiliation(s)
- C Manke
- Department of Radiology, University of Regensburg, Klinikum der Universität, Franz-Josef-Strauss-Allee 11, D-93042 Regensburg, Germany.
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39
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Fahrig R, Butts K, Rowlands JA, Saunders R, Stanton J, Stevens GM, Daniel BL, Wen Z, Ergun DL, Pelc NJ. A truly hybrid interventional MR/X-ray system: feasibility demonstration. J Magn Reson Imaging 2001; 13:294-300. [PMID: 11169837 DOI: 10.1002/1522-2586(200102)13:2<294::aid-jmri1042>3.0.co;2-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A system enabling both x-ray fluoroscopy and MRI in a single exam, without requiring patient repositioning, would be a powerful tool for image-guided interventions. We studied the technical issues related to acquisition of x-ray images inside an open MRI system (GE Signa SP). The system includes a flat-panel x-ray detector (GE Medical Systems) placed under the patient bed, a fixed-anode x-ray tube overhead with the anode-cathode axis aligned with the main magnetic field and a high-frequency x-ray generator (Lunar Corp.). New challenges investigated related to: 1) deflection and defocusing of the electron beam of the x-ray tube; 2) proper functioning of the flat panel; 3) effects on B0 field homogeneity; and 4) additional RF noise in the MR images. We have acquired high-quality x-ray and MR images without repositioning the object using our hybrid system, which demonstrates the feasibility of this new configuration. Further work is required to ensure that the highest possible image quality is achieved with both MR and x-ray modalities.
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Affiliation(s)
- R Fahrig
- Department of Radiology, Stanford University, Stanford, California 94305-5488, USA.
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40
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Fahrig R, Butts K, Rowlands JA, Saunders R, Stanton J, Stevens GM, Daniel BL, Wen Z, Ergun DL, Pelc NJ. A truly hybrid interventional MR/X-ray system: Feasibility demonstration. J Magn Reson Imaging 2001. [DOI: 10.1002/1522-2586(200102)13:2%3c294::aid-jmri1042%3e3.0.co;2-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Nitz WR, Oppelt A, Renz W, Manke C, Lenhart M, Link J. On the heating of linear conductive structures as guide wires and catheters in interventional MRI. J Magn Reson Imaging 2001; 13:105-14. [PMID: 11169811 DOI: 10.1002/1522-2586(200101)13:1<105::aid-jmri1016>3.0.co;2-0] [Citation(s) in RCA: 211] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The interest in performing vascular interventions under magnetic resonance (MR) guidance has initiated the evaluation of the potential hazard of long conductive wires and catheters. The objective of this work is to present a simple analytical approach to address this concern and to demonstrate the agreement with experimental results. The first hypothesis is that a long conductive structure couples with the electric field of the radio frequency (RF) transmit coil. The second hypothesis is that this coupling induces high voltages near the wire ends. These voltages can cause tissue heating due to induced currents. The experimental results show an increase in coupling when moving a guide wire toward the wall of an RF transmit coil, documented with a temperature increase of a saline solution in close proximity to the tip of the guide wire. The coupling of the wire not only presents a potential hazard to the patient, but also interferes with the visualization of the wire. A safe alternative would be the use of nonconducting guide wires. J. Magn. Reson. Imaging 2001;13:105-114.
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Affiliation(s)
- W R Nitz
- Department of Radiology, University of Regensburg, Germany.
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Kacher DF, Maier SE, Mamata H, Mamata Y, Nabavi A, Jolesz FA. Motion robust imaging for continuous intraoperative MRI. J Magn Reson Imaging 2001; 13:158-61. [PMID: 11169819 DOI: 10.1002/1522-2586(200101)13:1<158::aid-jmri1024>3.0.co;2-s] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The sensitivity of MR imaging to motion and susceptibility normally requires that the physician using intraoperative MRI cease surgical activity while image data sets are acquired. We demonstrate that line scan imaging allows the physician to continue operating without the delays caused by imaging. Consequently, patient anesthesia, surgery, and operating room time can be reduced. J. Magn. Reson. Imaging 2001;13:158-161.
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Affiliation(s)
- D F Kacher
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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43
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Nitz WR, Oppelt A, Renz W, Manke C, Lenhart M, Link J. On the heating of linear conductive structures as guide wires and catheters in interventional MRI. J Magn Reson Imaging 2001. [DOI: 10.1002/1522-2586(200101)13:1%3c105::aid-jmri1016%3e3.0.co;2-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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44
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Buecker A, Neuerburg JM, Adam GB, Glowinski A, Schaeffter T, Rasche V, van Vaals JJ, Molgaard-Nielsen A, Guenther RW. Real-time MR fluoroscopy for MR-guided iliac artery stent placement. J Magn Reson Imaging 2000; 12:616-22. [PMID: 11042645 DOI: 10.1002/1522-2586(200010)12:4<616::aid-jmri15>3.0.co;2-f] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The purpose of this study was to test the feasibility of real-time magnetic resonance (MR) guidance of iliac artery stent placement. Radial scanning together with the sliding window reconstruction technique was implemented on a 1.5 T magnet, yielding a frame rate of 20 images per second. Seven prototype nitinol ZA stents were deployed in iliac arteries of living pigs under MR control. All stents were well visualized on the radial MR images, allowing depiction of the mounted stents as well as stent deployment without anatomy-obscuring artifacts. Stent placement was sucessful in all cases and took 6 minutes on average. The position of the stents was correctly visualized by real-time radial MR scanning, as proved by digital subtraction X-ray angiography. Combined radial scanning and the sliding window reconstruction technique allow real-time MR-guided stent placement in iliac arteries.
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Affiliation(s)
- A Buecker
- Clinic for Diagnostic Radiology, University of Technology, D-52057 Aachen, Germany.
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Omary RA, Unal O, Koscielski DS, Frayne R, Korosec FR, Mistretta CA, Strother CM, Grist TM. Real-time MR imaging-guided passive catheter tracking with use of gadolinium-filled catheters. J Vasc Interv Radiol 2000; 11:1079-85. [PMID: 10997475 DOI: 10.1016/s1051-0443(07)61343-8] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE To test the hypothesis that real-time magnetic resonance (MR) imaging-guided passive catheter tracking is feasible with use of dilute gadolinium (Gd)-filled catheters, to determine the optimal Gd concentration required for tracking, and to measure catheter tip tracking accuracy. MATERIALS AND METHODS The authors tested a real-time, T1-weighted, two-dimensional, spoiled gradient-recalled echo MR imaging sequence suitable for tracking catheters. In a yogurt phantom, the authors placed 5-F catheters filled with 2%-12% Gd solutions. MR imaging was performed with and without use of a projection dephaser that suppressed background signal. The authors measured signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and enhancement ratio to determine the optimal Gd concentration for catheter depiction. Catheter tip tracking accuracy was measured in an acrylic phantom with use of linear regression analysis, with goodness of fit assessed statistically with the F test. RESULTS Peak catheter SNR, CNR, and enhancement ratios were obtained with 4%-6% Gd concentrations. Tip tracking accuracy was determined to be +/- 0.41 mm (R2 = 0.99; P < .0001). MR imaging reconstructions were displayed up to 3.1 frames/sec. CONCLUSIONS Accurate MR imaging-guided passive catheter tracking was feasible in real-time with use of dilute Gd-filled catheters. This technique may have application in MR imaging-guided endovascular procedures.
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Affiliation(s)
- R A Omary
- Department of Radiology, University of Wisconsin-Madison Medical School, USA.
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46
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Darcy M. Transjugular intrahepatic portosystemic shunt: Techniques for portal localization. Tech Vasc Interv Radiol 2000. [DOI: 10.1053/tvir.2000.9150] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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47
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Duerk JL, Butts K, Hwang KP, Lewin JS. Pulse sequences for interventional magnetic resonance imaging. Top Magn Reson Imaging 2000; 11:147-62. [PMID: 11145207 DOI: 10.1097/00002142-200006000-00001] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
Interventional magnetic resonance imaging (iMRI) is different from diagnostic magnetic resonance imaging (MRI) in its spatial, temporal, and contrast resolution requirements due to its specific clinical applications. As a result, the pulse sequences used in iMRI often are significantly different than those used in the more conventional diagnostic arena. The focus of this article is to summarize how iMRI is different from diagnostic MRI, to describe a variety of MRI pulse sequences and sequence strategies that have evolved because of these differences, and to describe some MRI sequence strategies that are in development and may be seen in future iMRI applications.
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Affiliation(s)
- J L Duerk
- Department of Radiology, Case Western Reserve University, Cleveland, Ohio, USA.
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48
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Manke C, Nitz WR, Lenhart M, Völk M, Geissler A, Feuerbach S, Link J. Magnetic resonance monitoring of stent deployment: in vitro evaluation of different stent designs and stent delivery systems. Invest Radiol 2000; 35:343-51. [PMID: 10853608 DOI: 10.1097/00004424-200006000-00002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
RATIONALE AND OBJECTIVES To evaluate MR imaging features of commercially available stents before, during, and after in vitro deployment as a step toward MR-guided stent deployment. METHODS Fourteen stents were deployed in a phantom under MR monitoring at 1.5 T by using a gradient-echo sequence. Device visibility was rated on a four-point scale (excellent, fair, poor, not visible). RESULTS The Memotherm stent and the rolling membrane (RM) Wallstent showed excellent stent visibility and at least fair scores for artifact-induced narrowing of the stent lumen. Three stents (Palmaz, AVE, Easy Wallstent) showed excellent visibility of the stent but no visible lumen. Five stents (Strecker, Accuflex, Hemobahn, Passager, Sinus) displayed fair visibility. The delivery catheters of four stent systems (Smart, Vascucoil, Symphony, ZA) displayed severe black hole artifacts. CONCLUSIONS The imaging features of several stent systems might be suitable for MR-guided intervention. The Memotherm and the Wallstent RM combine good visibility of the stent and the lumen.
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Affiliation(s)
- C Manke
- Department of Radiology, University of Regensburg, Germany
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Omary RA, Frayne R, Unal O, Warner T, Korosec FR, Mistretta CA, Strother CM, Grist TM. MR-guided angioplasty of renal artery stenosis in a pig model: a feasibility study. J Vasc Interv Radiol 2000; 11:373-81. [PMID: 10735435 DOI: 10.1016/s1051-0443(07)61433-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
PURPOSE To test the hypothesis that magnetic resonance (MR) imaging can guide the percutaneous treatment of renal artery stenosis in a pig model. MATERIALS AND METHODS Ameroid constrictors were surgically placed around six renal arteries in four pigs. After 30-36 days, all stenoses were documented by conventional x-ray aortograms. MR-guided renal angioplasty was attempted for three stenoses. For these pigs, MR angiography was performed with use of contrast-enhanced three-dimensional (3D) techniques. The authors visualized catheters by filling them with dilute 4% gadolinium and imaging with two-dimensional (2D) and 3D MR fast spoiled gradient recalled echo techniques. Under MR guidance, the authors advanced a selective catheter into the affected renal artery and crossed the stenosis with a nitinol guide wire. Angioplasty was performed with a balloon catheter filled with dilute gadolinium. Stenosis and luminal diameter measurements were compared before and after angioplasty. RESULTS After ameroid constrictor placement, four significant stenoses, one mild stenosis, and one occlusion developed. Under MR guidance, the authors achieved technical success in performing three of three (100%) attempted dilations. After MR-guided angioplasty, the mean reduction in stenosis was 35% and the mean increase in luminal diameter was 1.6 mm. CONCLUSION Use of MR guidance for the angioplasty of renal artery stenosis in pigs is feasible.
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Affiliation(s)
- R A Omary
- Department of Radiology, Medical Physics, and Pathology, University of Wisconsin-Madison Medical School, USA.
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