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Yaras YS, Yildirim DK, Herzka DA, Rogers T, Campbell-Washburn AE, Lederman RJ, Degertekin FL, Kocaturk O. Real-time device tracking under MRI using an acousto-optic active marker. Magn Reson Med 2020; 85:2904-2914. [PMID: 33347642 DOI: 10.1002/mrm.28625] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/30/2020] [Accepted: 11/09/2020] [Indexed: 12/31/2022]
Abstract
PURPOSE This work aims to demonstrate the use of an "active" acousto-optic marker with enhanced visibility and reduced radiofrequency (RF) -induced heating for interventional MRI. METHODS The acousto-optic marker was fabricated using bulk piezoelectric crystal and π-phase shifted fiber Bragg grating (FBGs) and coupled to a distal receiver coil on an 8F catheter. The received MR signal is transmitted over an optical fiber to mitigate RF-induced heating. A photodetector converts the optical signal into electrical signal, which is used as the input signal to the MRI receiver plug. Acousto-optic markers were characterized in phantom studies. RF-induced heating risk was evaluated according to ASTM 2182 standard. In vivo real-time tracking capability was tested in an animal model under a 0.55T scanner. RESULTS Signal-to-noise ratio (SNR) levels suitable for real-time tracking were obtained by using high sensitivity FBG and piezoelectric transducer with resonance matched to Larmor frequency. Single and multiple marker coils integrated to 8F catheters were readout for position and orientation tracking by a single acousto-optic sensor. RF-induced heating was significantly reduced compared to a coax cable connected reference marker. Real-time distal tip tracking of an active device was demonstrated in an animal model with a standard real-time cardiac MR sequence. CONCLUSION Acousto-optic markers provide sufficient SNR with a simple structure for real-time device tracking. RF-induced heating is significantly reduced compared to conventional active markers. Also, multiple RF receiver coils connected on an acousto-optic modulator can be used on a single catheter for determining catheter orientation and shape.
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Affiliation(s)
- Yusuf S Yaras
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Micromachined Sensors and Transducers Group, Atlanta, Georgia, USA
| | - Dursun Korel Yildirim
- National Institutes of Health, National Heart Lung and Blood Institute, Bethesda, Maryland, USA
| | - Daniel A Herzka
- National Institutes of Health, National Heart Lung and Blood Institute, Bethesda, Maryland, USA
| | - Toby Rogers
- National Institutes of Health, National Heart Lung and Blood Institute, Bethesda, Maryland, USA
| | | | - Robert J Lederman
- National Institutes of Health, National Heart Lung and Blood Institute, Bethesda, Maryland, USA
| | - F Levent Degertekin
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Micromachined Sensors and Transducers Group, Atlanta, Georgia, USA
| | - Ozgur Kocaturk
- Institute of Biomedical Engineering, Bogazici University, Kandilli Kampus, Istanbul, Turkey
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Nawka MT, Sedlacik J, Frölich A, Bester M, Fiehler J, Buhk JH. Multiparametric MRI of intracranial aneurysms treated with the Woven EndoBridge (WEB): a case of Faraday's cage? J Neurointerv Surg 2018; 10:988-994. [PMID: 29440326 DOI: 10.1136/neurintsurg-2017-013625] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/03/2018] [Accepted: 01/16/2018] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To evaluate multiparametric MRI including non-contrast and contrast-enhanced morphological and angiographic techniques for intracranial aneurysms treated with the single-layer Woven EndoBridge (WEB) embolization system applying simultaneous digital subtraction angiography (DSA) as the reference of standard. MATERIALS AND METHODS We retrospectively identified all patients with incidental and acute ruptured intracranial aneurysms treated with a WEB device (WEB SL and WEB SLS) between March 2014 and June 2016 in our neurovascular center with early (within 7 days) postinterventional multiparametric MRI as well as mid-term (5-8 months) follow-up MRI and DSA available. Occlusion rates were recorded both in DSA and MR angiography (MRA). In MRI, signal intensities within the WEB as well as in the occluded dome distal to the WEB, if present, were measured by region-of-interest (ROI) analysis. RESULTS Twenty-five patients fulfilled the inclusion criteria. Rates of complete/adequate occlusion at mid-term follow-up were 84% with both MRA and DSA. A strong signal loss within the WEB was observed in all MR sequences at initial and follow-up examinations. ROI analysis did not reveal significant differences in non-contrast (P=0.946) and contrast-enhanced imaging (P=0.377). A T1-hyperintense thrombus in the non-WEB-carrying dome was a frequent observation. CONCLUSIONS Signal intensity measurements in multiparametric MRI suggest that neither contrast-enhanced MRA nor morphological sequences are capable of revealing reliable information on the WEB lumen, presumably due to radio frequency shielding. MRI is therefore not suitable for confirming complete thrombus formation within the WEB.
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Affiliation(s)
- Marie Teresa Nawka
- Department of Diagnostic and Interventional Neuroradiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Jan Sedlacik
- Department of Diagnostic and Interventional Neuroradiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas Frölich
- Department of Diagnostic and Interventional Neuroradiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Maxim Bester
- Department of Diagnostic and Interventional Neuroradiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Jens Fiehler
- Department of Diagnostic and Interventional Neuroradiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Jan-Hendrik Buhk
- Department of Diagnostic and Interventional Neuroradiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
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de Arcos J, Schmidt EJ, Wang W, Tokuda J, Vij K, Seethamraju RT, Damato AL, Dumoulin CL, Cormack RA, Viswanathan AN. Prospective Clinical Implementation of a Novel Magnetic Resonance Tracking Device for Real-Time Brachytherapy Catheter Positioning. Int J Radiat Oncol Biol Phys 2017; 99:618-626. [PMID: 28843373 DOI: 10.1016/j.ijrobp.2017.05.054] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 05/05/2017] [Accepted: 05/31/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE We designed and built dedicated active magnetic resonance (MR)-tracked (MRTR) stylets. We explored the role of MRTR in a prospective clinical trial. METHODS AND MATERIALS Eleven gynecologic cancer patients underwent MRTR to rapidly optimize interstitial catheter placement. MRTR catheter tip location and orientation were computed and overlaid on images displayed on in-room monitors at rates of 6 to 16 frames per second. Three modes of actively tracked navigation were analyzed: coarse navigation to the approximate region around the tumor; fine-tuning, bringing the stylets to the desired location; and pullback, with MRTR stylets rapidly withdrawn from within the catheters, providing catheter trajectories for radiation treatment planning (RTP). Catheters with conventional stylets were inserted, forming baseline locations. MRTR stylets were substituted, and catheter navigation was performed by a clinician working inside the MRI bore, using monitor feedback. RESULTS Coarse navigation allowed repositioning of the MRTR catheters tips by 16 mm (mean), relative to baseline, in 14 ± 5 s/catheter (mean ± standard deviation [SD]). The fine-tuning mode repositioned the catheter tips by a further 12 mm, in 24 ± 17 s/catheter. Pullback mode provided catheter trajectories with RTP point resolution of ∼1.5 mm, in 1 to 9 s/catheter. CONCLUSIONS MRTR-based navigation resulted in rapid and optimal placement of interstitial brachytherapy catheters. Catheters were repositioned compared with the initial insertion without tracking. In pullback mode, catheter trajectories matched computed tomographic precision, enabling their use for RTP.
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Affiliation(s)
- Jose de Arcos
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts.
| | - Ehud J Schmidt
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts; Department of Medicine, Johns Hopkins Medicine, Baltimore, Maryland
| | - Wei Wang
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts
| | - Junichi Tokuda
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts
| | - Kamal Vij
- Department of Radiation Oncology, Brigham and Women's Hospital, Boston, Massachusetts
| | | | - Antonio L Damato
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | | | - Robert A Cormack
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Akila N Viswanathan
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins Sidney Kimmel Cancer Center, Baltimore, Maryland.
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Abstract
Several advantages of MR imaging compared with other imaging modalities have provided the rationale for increased attention to MR-guided interventions, including its excellent soft tissue contrast, its capability to show both anatomic and functional information, and no use of ionizing radiation. An important aspect of MR-guided intervention is to provide visualization and navigation of interventional devices relative to the surrounding tissues. This article focuses on the methods for MR-guided active tracking in catheter-based interventions. Practical issues about implementation of active catheter tracking in a clinical setting are discussed and several current application examples are highlighted.
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Affiliation(s)
- Wei Wang
- Radiology, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA.
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Reiss S, Bitzer A, Bock M. An optical setup for electric field measurements in MRI with high spatial resolution. Phys Med Biol 2015; 60:4355-70. [PMID: 25984961 DOI: 10.1088/0031-9155/60/11/4355] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Wang W, Dumoulin CL, Viswanathan AN, Tse ZTH, Mehrtash A, Loew W, Norton I, Tokuda J, Seethamraju RT, Kapur T, Damato AL, Cormack RA, Schmidt EJ. Real-time active MR-tracking of metallic stylets in MR-guided radiation therapy. Magn Reson Med 2014; 73:1803-11. [PMID: 24903165 DOI: 10.1002/mrm.25300] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 05/01/2014] [Accepted: 05/02/2014] [Indexed: 11/10/2022]
Abstract
PURPOSE To develop an active MR-tracking system to guide placement of metallic devices for radiation therapy. METHODS An actively tracked metallic stylet for brachytherapy was constructed by adding printed-circuit micro-coils to a commercial stylet. The coil design was optimized by electromagnetic simulation, and has a radio-frequency lobe pattern extending ∼5 mm beyond the strong B0 inhomogeneity region near the metal surface. An MR-tracking sequence with phase-field dithering was used to overcome residual effects of B0 and B1 inhomogeneities caused by the metal, as well as from inductive coupling to surrounding metallic stylets. The tracking system was integrated with a graphical workstation for real-time visualization. The 3 Tesla MRI catheter-insertion procedures were tested in phantoms and ex vivo animal tissue, and then performed in three patients during interstitial brachytherapy. RESULTS The tracking system provided high-resolution (0.6 × 0.6 × 0.6 mm(3) ) and rapid (16 to 40 frames per second, with three to one phase-field dithering directions) catheter localization in phantoms, animals, and three gynecologic cancer patients. CONCLUSION This is the first demonstration of active tracking of the shaft of metallic stylet in MR-guided brachytherapy. It holds the promise of assisting physicians to achieve better targeting and improving outcomes in interstitial brachytherapy.
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Affiliation(s)
- Wei Wang
- Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA; Radiation Oncology, Brigham and Women's Hospital, Boston, Massachusetts, USA
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Fandrey S, Weiss S, Müller J. A novel active MR probe using a miniaturized optical link for a 1.5-T MRI scanner. Magn Reson Med 2011; 67:148-55. [PMID: 21837807 DOI: 10.1002/mrm.23002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 04/20/2011] [Accepted: 04/21/2011] [Indexed: 11/07/2022]
Abstract
Applying an active intravascular MR catheter device that allows signal transmission from the catheter tip requires special means to avoid radiofrequency-induced heating. This article presents a novel, miniaturized all-optical active MR probe to use with real-time MRI in minimally invasive interventions for catheter guidance and intravascular imaging. An optical link transmits the received MR signals from the catheter tip to the MR receiver with inherently radiofrequency-safe optical fibers. Furthermore, power is supplied optically to the transmitter as well. The complete integration into a small tube of 6-Fr (2-mm diameter) size with a 7-Fr (2.33-mm diameter) rigid tubing was realized using chip components for the optical modulator and a novel miniaturized optical bench fabricated from silicon substrates with 3D self-aligning structures for fiber integration. In MRI phantom measurements, projection-based tip tracking and high-resolution imaging were successfully performed with the optical link inside a 1.5-T MRI scanner. Images were obtained in a homogeneous phantom liquid, and first pictures were acquired from inside a kiwi that demonstrates the potential of the MR-safe optical link. The signal-to-noise ratio has significantly improved compared with former systems, and it is demonstrated that the novel optical link exhibits a signal-to-noise ratio comparable to a direct electrical link.
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Affiliation(s)
- Stephan Fandrey
- Institute of Micro Systems Technology, Hamburg University of Technology, Hamburg, Germany.
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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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Fandrey S, Weiss S, Muller J. Development of an active intravascular MR device with an optical transmission system. IEEE TRANSACTIONS ON MEDICAL IMAGING 2008; 27:1723-1727. [PMID: 19033088 DOI: 10.1109/tmi.2008.925079] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Magnetic resonance imaging (MRI) is a safe and reliable medical imaging method providing good soft tissue contrast while avoiding harmful ionizing radiation. It is highly desirable to use the MRI technology for interventional procedures. However, due to resonance effects that can result in tissue heating, long conducting cables must be avoided. Motivated by the need for more radio-frequency (RF) safety, we developed an optical transmission system for active intravascular MRI devices. An optical transmitter sends the MR signal via an optical fiber. A miniature optical modulator was designed to be integrated into a catheter tip. Furthermore, power is supplied optically to the transmitter. This system can target new medical applications, due to safe catheter tracking and safe intravascular imaging.
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Affiliation(s)
- Stephan Fandrey
- Hamburg University of Technology, Institute of MicroSystems Technology, 21073 Hamburg, Germany.
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Bock M, Wacker FK. MR-guided intravascular interventions: techniques and applications. J Magn Reson Imaging 2008; 27:326-38. [PMID: 18219686 DOI: 10.1002/jmri.21271] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Magnetic resonance imaging (MRI) offers several advantages over other imaging modalities that make it an attractive imaging tool for diagnostic and therapeutic procedures. This tremendous potential of MRI has provided the rationale for increased attention toward MR-guided endovascular interventions. MR guidance has been used recently to navigate endovascular catheters and deliver stents, vena cava filters, embolization materials, and septum closure devices. However, its potential goes beyond just copying existing procedures toward the development of new minimally invasive techniques that cannot be performed with conventional guiding techniques. Because of technical limitations and safety issues associated with some of the currently available devices, a limited number of clinical studies have been performed so far. The overall success for this developing field requires considerable interdisciplinary research within both the interventional and the MR community. Only through a combined effort can this complex technology find its way into clinical practice. This review discusses the hardware and software improvements that have helped to advance endovascular interventions under MR imaging guidance from a pure research tool to become a clinical reality. In addition, technical and safety issues specific to endovascular MR image guidance will be described and practical applications will be shown that take advantage of the benefits of MR for endovascular interventions.
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Affiliation(s)
- Michael Bock
- Deutsches Krebsforschungszentrum, Department of Medical Physics in Radiology (E020), Heidelberg, Germany
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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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12
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Krafft A, Müller S, Umathum R, Semmler W, Bock M. B1 field-insensitive transformers for RF-safe transmission lines. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2006; 19:257-66. [PMID: 17115123 DOI: 10.1007/s10334-006-0055-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 10/11/2006] [Accepted: 10/12/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Integration of transformers into transmission lines suppresses radiofrequency (RF)-induced heating. New figure-of-eight-shaped transformer coils are compared to conventional loop transformer coils to assess their signal transmission properties and safety profile. MATERIALS AND METHODS The transmission properties of figure-of-eight-shaped transformers were measured and compared to transformers with loop coils. Experiments to quantify the effect of decoupling from the B1 field of the MR system were conducted. Temperature measurements were performed to demonstrate the effective reduction of RF-induced heating. The transformers were investigated during active tracking experiments. RESULTS Coupling to the B1 field was reduced by 18 dB over conventional loop-shaped transformer coils. MR images showed a significantly reduced artifact for the figure-of-eight- shaped coils generated by local flip-angle amplification. Comparable transmission properties were seen for both transformer types. Temperature measurements showed a maximal temperature increase of 30 K/3.5 K for an unsegmented/segmented cable. With a segmented transmission line a robotic assistance system could be successfully localized using active tracking. CONCLUSION The figure-of-eight-shaped transformer design reduces both RF field coupling with the MR system and artifact sizes. Anatomical structure close to the figure-of-eight-shaped transformer may be less obscured as with loop-shaped transformers if these transformers are integrated into e.g. intravascular catheters.
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Affiliation(s)
- Axel Krafft
- Deutsches Krebsforschungszentrum (dkfz), Abt. Medizinische Physik in der Radiologie (E020), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
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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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