1
|
Yildirim DK, Uzun D, Bruce CG, Khan JM, Rogers T, Schenke WH, Ramasawmy R, Campbell-Washburn A, Herzka D, Lederman RJ, Kocaturk O. An interventional MRI guidewire combining profile and tip conspicuity for catheterization at 0.55T. Magn Reson Med 2023; 89:845-858. [PMID: 36198118 PMCID: PMC9712240 DOI: 10.1002/mrm.29466] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 08/04/2022] [Accepted: 09/02/2022] [Indexed: 12/13/2022]
Abstract
PURPOSE We describe a clinical grade, "active", monopole antenna-based metallic guidewire that has a continuous shaft-to-tip image profile, a pre-shaped tip-curve, standard 0.89 mm (0.035″) outer diameter, and a detachable connector for catheter exchange during cardiovascular catheterization at 0.55T. METHODS Electromagnetic simulations were performed to characterize the magnetic field around the antenna whip for continuous tip visibility. The active guidewire was manufactured using medical grade materials in an ISO Class 7 cleanroom. RF-induced heating of the active guidewire prototype was tested in one gel phantom per ASTM 2182-19a, alone and in tandem with clinical metal-braided catheters. Real-time MRI visibility was tested in one gel phantom and in-vivo in two swine. Mechanical performance was compared with commercial equivalents. RESULTS The active guidewire provided continuous "profile" shaft and tip visibility in-vitro and in-vivo, analogous to guidewire shaft-and-tip profiles under X-ray. The MRI signal signature matched simulation results. Maximum unscaled RF-induced temperature rise was 5.2°C and 6.5°C (3.47 W/kg local background specific absorption rate), alone and in tandem with a steel-braided catheter, respectively. Mechanical characteristics matched commercial comparator guidewires. CONCLUSION The active guidewire was clearly visible via real-time MRI at 0.55T and exhibits a favorable geometric sensitivity profile depicting the guidewire continuously from shaft-to-tip including a unique curved-tip signature. RF-induced heating is clinically acceptable. This design allows safe device navigation through luminal structures and heart chambers. The detachable connector allows delivery and exchange of cardiovascular catheters while maintaining guidewire position. This enhanced guidewire design affords the expected performance of X-ray guidewires during human MRI catheterization.
Collapse
Affiliation(s)
- Dursun Korel Yildirim
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
| | - Dogangun Uzun
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
- Institute of Biomedical Engineering, Bogazici University, Istanbul, Turkey
| | - Christopher G. Bruce
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
| | - Jaffar M. Khan
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
| | - Toby Rogers
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
| | - William H. Schenke
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
| | - Rajiv Ramasawmy
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
| | - Adrienne Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
| | - Daniel Herzka
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
| | - Robert J. Lederman
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, MD, USA
| | - Ozgur Kocaturk
- Institute of Biomedical Engineering, Bogazici University, Istanbul, Turkey
| |
Collapse
|
2
|
Meng Y, Mo Z, Hao J, Peng Y, Yan H, Mu J, Ma D, Zhang X, Li Y. High-resolution intravascular magnetic resonance imaging of the coronary artery wall at 3.0 Tesla: toward evaluation of atherosclerotic plaque vulnerability. Quant Imaging Med Surg 2021; 11:4522-4529. [PMID: 34737920 DOI: 10.21037/qims-21-286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/05/2021] [Indexed: 11/06/2022]
Abstract
Background To validate the feasibility of generating high-resolution intravascular 3.0 Tesla (T) magnetic resonance imaging of the coronary artery wall to further plaque imaging. Methods A receive-only 0.014-inch diameter magnetic resonance imaging guidewire (MRIG) was manufactured for intravascular imaging within a phantom experiment and the coronary artery wall of the swine. For coronary artery wall imaging, both high-resolution images and conventional resolution images were acquired. A 16-channel commercial surface coil for magnetic resonance imaging was employed for the control group. Results For the phantom experiment, the MRIG showed a higher signal-to-noise ratio than the surface coil. The peak signal-to-noise ratio of the MRIG and the surface coil-generated imaging were 213.6 and 19.8, respectively. The signal-to-noise ratio decreased rapidly as the distance from the MRIG increased. For the coronary artery wall experiment, the vessel wall imaging by the MRIG could be identified clearly, whereas the vessel wall imaging by the surface coil was blurred. The average signal-to-noise ratio of the artery wall was 21.1±5.40 by the MRIG compared to 8.4±2.19 by the surface coil, where the resolution was set at 0.2 mm × 0.2 mm × 2 mm. As expected, the high-resolution sequence clearly showed more details than the conventional resolution sequence set at 0.7 mm × 0.7 mm × 2.0 mm. Histological examination showed no evidence of mechanical injuries in the target vessel walls. Conclusions The study validated the feasibility of generating magnetic resonance imaging (MRI) at 0.2 mm × 0.2 mm × 2 mm for the coronary artery wall using a 0.014 inch MRIG.
Collapse
Affiliation(s)
- Yanfeng Meng
- Department of MRI, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Zhiguang Mo
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,The Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen, China
| | - Jinying Hao
- Department of MRI, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Yueyou Peng
- Department of MRI, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Hui Yan
- Department of MRI, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Jingbo Mu
- Department of Cardiology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Dengfeng Ma
- Department of Cardiology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, China
| | - Xiaoliang Zhang
- Department of Biomedical Engineering, State University of New York at Buffalo, NY, USA
| | - Ye Li
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,The Key Laboratory for Magnetic Resonance and Multimodality Imaging of Guangdong Province, Shenzhen, China
| |
Collapse
|
3
|
Schmidt EJ, Halperin HR. MRI use for atrial tissue characterization in arrhythmias and for EP procedure guidance. Int J Cardiovasc Imaging 2018; 34:81-95. [PMID: 28593399 PMCID: PMC5889521 DOI: 10.1007/s10554-017-1179-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 05/24/2017] [Indexed: 12/19/2022]
Abstract
We review the utilization of magnetic resonance imaging methods for classifying atrial tissue properties that act as a substrate for common cardiac arrhythmias, such as atrial fibrillation. We then review state-of-the-art methods for mapping this substrate as a predicate for treatment, as well as methods used to ablate the electrical pathways that cause arrhythmia and restore patients to sinus rhythm.
Collapse
Affiliation(s)
- Ehud J Schmidt
- Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
| | - Henry R Halperin
- Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| |
Collapse
|
4
|
Etezadi-Amoli M, Stang P, Kerr A, Pauly J, Scott G. Interventional device visualization with toroidal transceiver and optically coupled current sensor for radiofrequency safety monitoring. Magn Reson Med 2014; 73:1315-27. [PMID: 24691876 DOI: 10.1002/mrm.25187] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 01/25/2014] [Accepted: 01/28/2014] [Indexed: 11/09/2022]
Abstract
PURPOSE The development of catheters and guidewires that are safe from radiofrequency (RF) -induced heating and clearly visible against background tissue is a major challenge in interventional MRI. An interventional imaging approach using a toroidal transmit-receive (transceive) coil is presented. This toroidal transceiver allows controlled, low levels of RF current to flow in the catheter/guidewire for visualization, and can be used with conductive interventional devices that have a localized low-impedance tip contact. METHODS Toroidal transceivers were built, and phantom experiments were performed to quantify transmit power levels required for device visibility and to detect heating hazards. Imaging experiments in a pig cadaver tested the extendibility to higher field strength and nonphantom settings. A photonically powered optically coupled toroidal current sensor for monitoring induced RF currents was built, calibrated, and tested using an independent image-based current estimation method. RESULTS Results indicate that high signal-to-noise ratio visualization is achievable using milliwatts of transmit power-power levels orders of magnitude lower than levels that induce measurable heating in phantom tests. Agreement between image-based current estimates and RF current sensor measurements validates sensor accuracy. CONCLUSION The toroidal transceiver, integrated with power and current sensing, could offer a promising platform for safe and effective interventional device visualization.
Collapse
Affiliation(s)
- Maryam Etezadi-Amoli
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | | | | | | | | |
Collapse
|
5
|
Sapontis J, Hill J. The role of adjunctive imaging in chronic total occlusions. Interv Cardiol 2013. [DOI: 10.2217/ica.13.62] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
6
|
Syms RRA, Young IR, Ahmad MM, Taylor-Robinson SD, Rea M. Magneto-inductive catheter receiver for magnetic resonance imaging. IEEE Trans Biomed Eng 2013; 60:2421-31. [PMID: 23591471 DOI: 10.1109/tbme.2013.2258020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A catheter-based RF receiver for internal magnetic resonance imaging is demonstrated. The device consists of a double-sided thin-film circuit, wrapped around a hollow catheter and sealed in place with heat-shrink tubing. Signals are detected using a resonant LC circuit at the catheter tip and transmitted along the catheter using an array of coupled LC circuits arranged as a magneto-inductive waveguide, a form of low frequency metamaterial. Coupling to a conventional RF system is accomplished using a demountable inductive transducer. Protection against external B 1 and E fields is obtained by using figure-of-eight elements with an electrical length shorter than that of an immersed dipole. The system is primarily designed for biliary imaging, can pass the biopsy channel of a side-opening duodenoscope, and is guidewire-compatible, potentially allowing clinicians to implement MR image guided procedures without changing their standard practice. Decoupling against B 1 and E fields is verified, and in vitro (1)H magnetic resonance imaging with submillimeter resolution is demonstrated at 1.5 T using phantoms.
Collapse
Affiliation(s)
- Richard R A Syms
- Department of Electrical and Electronic Engineering, Imperial College London, London, SW7 2AZ, UK.
| | | | | | | | | |
Collapse
|
7
|
An intravascular loopless monopole antenna for vessel wall MR imaging at 3.0 T. Magn Reson Imaging 2013; 31:150-5. [PMID: 22902470 DOI: 10.1016/j.mri.2012.06.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 06/05/2012] [Accepted: 06/26/2012] [Indexed: 11/21/2022]
|
8
|
Ginefri JC, Rubin A, Tatoulian M, Woytasik M, Boumezbeur F, Djemaï B, Poirier-Quinot M, Lethimonnier F, Darrasse L, Dufour-Gergam E. Implanted, inductively-coupled, radiofrequency coils fabricated on flexible polymeric material: application to in vivo rat brain MRI at 7 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 224:61-70. [PMID: 23041797 DOI: 10.1016/j.jmr.2012.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 09/01/2012] [Accepted: 09/09/2012] [Indexed: 06/01/2023]
Abstract
Combined with high-field MRI scanners, small implanted coils allow for high resolution imaging with locally improved SNR, as compared to external coils. Small flexible implantable coils dedicated to in vivo MRI of the rat brain at 7 T were developed. Based on the Multi-turn Transmission Line Resonator design, they were fabricated with a Teflon substrate using copper micromolding process and a specific metal-polymer adhesion treatment. The implanted coils were made biocompatible by PolyDimethylSiloxane (PDMS) encapsulation. The use of low loss tangent material achieves low dielectric losses within the substrate and the use of the PDMS layer reduces the parasitic coupling with the surrounding media. An implanted coil was implemented in a 7 T MRI system using inductive coupling and a dedicated external pick-up coil for signal transmission. In vivo images of the rat brain acquired with in plane resolution of (150 μm)(2) thanks to the implanted coil revealed high SNR near the coil, allowing for the visualization of fine cerebral structures.
Collapse
Affiliation(s)
- J-C Ginefri
- IR4M, Université Paris-Sud, UMR8081, F-91405 Orsay, France.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Sonmez M, Saikus CE, Bell JA, Franson DN, Halabi M, Faranesh AZ, Ozturk C, Lederman RJ, Kocaturk O. MRI active guidewire with an embedded temperature probe and providing a distinct tip signal to enhance clinical safety. J Cardiovasc Magn Reson 2012; 14:38. [PMID: 22720758 PMCID: PMC3419092 DOI: 10.1186/1532-429x-14-38] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 05/28/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The field of interventional cardiovascular MRI is hampered by the unavailability of active guidewires that are both safe and conspicuous. Heating of conductive guidewires is difficult to predict in vivo and disruptive to measure using external probes. We describe a clinical-grade 0.035" (0.89 mm) guidewire for MRI right and left heart catheterization at 1.5 T that has an internal probe to monitor temperature in real-time, and that has both tip and shaft visibility as well as suitable flexibility. METHODS The design has an internal fiberoptic temperature probe, as well as a distal solenoid to enhance tip visibility on a loopless antenna. We tested different tip-solenoid configurations to balance heating and signal profiles. We tested mechanical performance in vitro and in vivo in comparison with a popular clinical nitinol guidewire. RESULTS The solenoid displaced the point of maximal heating ("hot spot") from the tip to a more proximal location where it can be measured without impairing guidewire flexion. Probe pullback allowed creation of lengthwise guidewire temperature maps that allowed rapid evaluation of design prototypes. Distal-only solenoid attachment offered the best compromise between tip visibility and heating among design candidates. When fixed at the hot spot, the internal probe consistently reflected the maximum temperature compared external probes.Real-time temperature monitoring was performed during porcine left heart catheterization. Heating was negligible using normal operating parameters (flip angle, 45°; SAR, 1.01 W/kg); the temperature increased by 4.2°C only during high RF power mode (flip angle, 90°; SAR, 3.96 W/kg) and only when the guidewire was isolated from blood cooling effects by an introducer sheath. The tip flexibility and in vivo performance of the final guidewire design were similar to a popular commercial guidewire. CONCLUSIONS We integrated a fiberoptic temperature probe inside a 0.035" MRI guidewire. Real-time monitoring helps detect deleterious heating during use, without impairing mechanical guidewire operation, and without impairing MRI visibility. We therefore need not rely on prediction to ensure safe clinical operation. Future implementations may modulate specific absorption rate (SAR) based on temperature feedback.
Collapse
Affiliation(s)
- Merdim Sonmez
- Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Institute of Biomedical Engineering, Bogazici University, Istanbul, Turkey
| | - Christina E Saikus
- Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jamie A Bell
- Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dominique N Franson
- Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Majdi Halabi
- Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anthony Z Faranesh
- Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Cengizhan Ozturk
- Institute of Biomedical Engineering, Bogazici University, Istanbul, Turkey
| | - Robert J Lederman
- Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ozgur Kocaturk
- Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| |
Collapse
|
10
|
Ertürk MA, El-Sharkawy AMM, Bottomley PA. Interventional loopless antenna at 7 T. Magn Reson Med 2011; 68:980-8. [PMID: 22161992 DOI: 10.1002/mrm.23280] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 09/02/2011] [Accepted: 10/10/2011] [Indexed: 11/12/2022]
Abstract
The loopless antenna magnetic resonance imaging detector is comprised of a tuned coaxial cable with an extended central conductor that can be fabricated at submillimeter diameters for interventional use in guidewires, catheters, or needles. Prior work up to 4.7 T suggests a near-quadratic gain in signal-to-noise ratio with field strength and safe operation at 3 T. Here, for the first time, the signal-to-noise ratio performance and radiofrequency safety of the loopless antenna are investigated both theoretically, using the electromagnetic method-of-moments, and experimentally in a standard 7 T human scanner. The results are compared with equivalent 3 T devices. An absolute signal-to-noise ratio gain of 5.7 ± 1.5-fold was realized at 7 T vs. 3 T: more than 20-fold higher than at 1.5 T. The effective field-of-view area also increased approximately 10-fold compared with 3 T. Testing in a saline gel phantom suggested that safe operation is possible with maximum local 1-g average specific absorption rates of <12 W kg(-1) and temperature increases of <1.9°C, normalized to a 4 W kg(-1) radiofrequency field exposure at 7 T. The antenna did not affect the power applied to the scanner's transmit coil. The signal-to-noise ratio gain enabled magnetic resonance imaging microscopy at 40-50 μm resolution in diseased human arterial specimens, offering the potential of high-resolution large-field-of-view or endoscopic magnetic resonance imaging for targeted intervention in focal disease.
Collapse
Affiliation(s)
- Mehmet Arcan Ertürk
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland, United States of America
| | | | | |
Collapse
|
11
|
Qian D, El-Sharkawy AMM, Atalar E, Bottomley PA. Interventional MRI: tapering improves the distal sensitivity of the loopless antenna. Magn Reson Med 2010; 63:797-802. [PMID: 20187186 DOI: 10.1002/mrm.22152] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The "loopless antenna" is an interventional MRI detector consisting of a tuned coaxial cable and an extended inner conductor or "whip". A limitation is the poor sensitivity afforded at, and immediately proximal to, its distal end, which is exacerbated by the extended whip length when the whip is uniformly insulated. It is shown here that tapered insulation dramatically improves the distal sensitivity of the loopless antenna by pushing the current sensitivity toward the tip. The absolute signal-to-noise ratio is numerically computed by the electromagnetic method-of-moments for three resonant 3-T antennae with no insulation, uniform insulation, and with linearly tapered insulation. The analysis shows that tapered insulation provides an approximately 400% increase in signal-to-noise ratio in trans-axial planes 1 cm from the tip and a 16-fold increase in the sensitive area as compared to an equivalent, uniformly insulated antenna. These findings are directly confirmed by phantom experiments and by MRI of an aorta specimen. The results demonstrate that numerical electromagnetic signal-to-noise ratio analysis can accurately predict the loopless detector's signal-to-noise ratio and play a central role in optimizing its design. The manifold improvement in distal signal-to-noise ratio afforded by redistributing the insulation should improve the loopless antenna's utility for interventional MRI.
Collapse
Affiliation(s)
- Di Qian
- Division of MR Research, Department of Radiology, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21287, USA
| | | | | | | |
Collapse
|
12
|
Gilbert G, Soulez G, Beaudoin G. Improved in-stent lumen visualization using intravascular MRI and a balanced steady-state free-precession sequence. Acad Radiol 2009; 16:1466-74. [PMID: 19836269 DOI: 10.1016/j.acra.2009.07.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 07/01/2009] [Accepted: 07/06/2009] [Indexed: 11/26/2022]
Abstract
RATIONALE AND OBJECTIVES To investigate the ability of an intravascular magnetic resonance (MR) loopless antenna to reduce the radiofrequency shielding of a vascular stent during signal reception as a way to improve the visualization of the in-stent lumen. METHODS AND MATERIALS Using a balanced steady-state free-precession (bSSFP) sequence and a dedicated vascular phantom, the signal-to-noise ratio (SNR) inside the lumen of a stent is evaluated as a function of the nominal flip angle and compared with the results obtained for a reference vessel without a stent. All experiments are performed using successively an intravascular loopless antenna and surface arrays coils. Using an optimized protocol, in vitro in-stent restenosis visualization and quantification experiments are performed to evaluate the validity of an approach using an intravascular antenna and cross-sectional images to depict a vascular lesion inside a stent. RESULTS The use of a loopless antenna effectively eliminates the radiofrequency shielding effect of the stent during signal reception. Furthermore, using a bSSFP sequence with a carefully chosen nominal flip angle, an equally good blood SNR can be obtained inside and outside the stent. Results of in vitro in-stent restenosis quantification measurements using the proposed method illustrate the benefits arising from the use of the intravascular antenna. CONCLUSION In the perspective of MR-guided vascular interventions, the presented results illustrate that the use of an intravascular antenna can significantly facilitate imaging inside a vascular stent. Potential applications include the monitoring of stent deployment as well as visualization and quantification of in-stent restenosis during an intervention.
Collapse
|
13
|
Kocaturk O, Kim AH, Saikus CE, Guttman MA, Faranesh AZ, Ozturk C, Lederman RJ. Active two-channel 0.035'' guidewire for interventional cardiovascular MRI. J Magn Reson Imaging 2009; 30:461-5. [PMID: 19629968 DOI: 10.1002/jmri.21844] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To develop an "active" (receiver-coil) clinical-grade guidewire with enhanced visibility for magnetic resonance imaging (MRI) and favorable mechanical characteristics for interventional MRI procedures that require conspicuous intravascular instruments distinguishable from surrounding tissues. MATERIALS AND METHODS We designed a 0.035-inch guidewire combining two antenna designs on separate channels. A loop antenna visualizes the tip and a dipole antenna visualizes the whole shaft. We compared mechanical characteristics of this guidewire with x-ray alternatives and tested MRI performance at 1.5T in vitro and in vivo in swine. RESULTS Images reflected tip position within 0.97 +/- 0.42 mm and afforded whole-shaft visibility under expected conditions without sacrificing device size or handling. We report tip stiffness, torquability, and pushability comparable to commercial interventional guidewires. CONCLUSION Our clinical-grade 0.035-inch active guidewire is conspicuous under MRI and has mechanical performance comparable to x-ray interventional guidewires. This may enable a range of interventional procedures using real-time MRI.
Collapse
Affiliation(s)
- Ozgur Kocaturk
- Translational Medicine Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-1061, USA.
| | | | | | | | | | | | | |
Collapse
|
14
|
Gilbert G, Soulez G, Beaudoin G. Comparative evaluation of the geometrical accuracy of intravascular magnetic resonance imaging: a phantom study. Acad Radiol 2009; 16:988-96. [PMID: 19394874 DOI: 10.1016/j.acra.2009.02.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 02/18/2009] [Accepted: 02/18/2009] [Indexed: 11/26/2022]
Abstract
RATIONALE AND OBJECTIVES To evaluate and compare the accuracy of cross-sectional imaging using an intravascular antenna in the context of vascular morphological measurements performed during a magnetic resonance imaging (MRI)-guided vascular intervention. MATERIALS AND METHODS Cross-sectional imaging of a multimodality vascular phantom was performed using intravascular and surface MRI, multidetector computed tomography, and intravascular ultrasound (IVUS). Using a balanced steady-state free-precession sequence, 18 sequences parameters sets were investigated (12 for intravascular MRI and 6 for surface MRI). Vessel diameters for all images and modalities were computed using an automated vessel segmentation algorithm. RESULTS Using IVUS as a gold standard, imaging using an intravascular antenna leads to an increase in geometrical accuracy in comparison to traditional surface MRI. This level of accuracy appears to follow a significant inverse proportionality relation in respect to vessel wall signal-to-noise ratio (SNR). Taking into account the rapid decrease in SNR as a function of the distance to the intravascular antenna, these results imply that, for a given level of geometrical accuracy, faster sequences can be used for the imaging of smaller vessels. CONCLUSION Imaging using an intravascular antenna appears as a valuable assistance to increase the accuracy of vascular morphological measurements. This increase in geometrical accuracy would be beneficial during the realization of an MRI-guided intervention, either to perform pretreatment measurements or to assess the outcome of the procedure. Acquisition parameters should be tailored to vessel size and procedural time constraints.
Collapse
|
15
|
Horvath KA, Li M, Mazilu D, Guttman MA, McVeigh ER. Real-time magnetic resonance imaging guidance for cardiovascular procedures. Semin Thorac Cardiovasc Surg 2008; 19:330-5. [PMID: 18395633 DOI: 10.1053/j.semtcvs.2007.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2007] [Indexed: 12/20/2022]
Abstract
Magnetic resonance imaging (MRI) of the cardiovascular system has proven to be an invaluable diagnostic tool. Given the ability to allow for real-time imaging, MRI guidance of intraoperative procedures can provide superb visualization, which can facilitate a variety of interventions and minimize the trauma of the operations as well. In addition to the anatomic detail, MRI can provide intraoperative assessment of organ and device function. Instruments and devices can be marked to enhance visualization and tracking, all of which is an advance over standard X-ray or ultrasonic imaging.
Collapse
Affiliation(s)
- Keith A Horvath
- Cardiothoracic Surgery Research Program, National Heart, Lung, and Blood Institute (NHLBI), NIH, Bethesda, MD 20892, USA.
| | | | | | | | | |
Collapse
|
16
|
Real-time MR imaging-guided laser atrial septal puncture in swine. J Vasc Interv Radiol 2008; 19:1347-53. [PMID: 18725098 DOI: 10.1016/j.jvir.2008.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Revised: 05/05/2008] [Accepted: 05/12/2008] [Indexed: 11/23/2022] Open
Abstract
PURPOSE The authors performed this study to report their initial preclinical experience with real-time magnetic resonance (MR) imaging-guided atrial septal puncture by using a MR imaging-conspicuous blunt laser catheter that perforates only when energized. MATERIALS AND METHODS The authors customized a 0.9-mm clinical excimer laser catheter with a receiver coil to impart MR imaging visibility at 1.5 T. Seven swine underwent laser transseptal puncture under real-time MR imaging. MR imaging signal-to-noise ratio profiles of the device were obtained in vitro. Tissue traversal force was tested with a calibrated meter. Position was corroborated with pressure measurements, oximetry, angiography, and necropsy. Intentional non-target perforation simulated serious complication. RESULTS Embedded MR imaging antennae accurately reflected the position of the laser catheter tip and profile in vitro and in vivo. Despite having an increased profile from the microcoil, the 0.9-mm laser catheter traversed in vitro targets with similar force (0.22 N +/- 0.03) compared with the unmodified laser. Laser puncture of the atrial septum was successful and accurate in all animals. The laser was activated an average of 3.8 seconds +/- 0.4 before traversal. There were no sequelae after 6 hours of observation. Necropsy revealed 0.9-mm holes in the fossa ovalis in all animals. Intentional perforation of the aorta and atrial free wall was evident immediately. CONCLUSIONS MR imaging-guided laser puncture of the interatrial septum is feasible in swine and offers controlled delivery of perforation energy by using an otherwise blunt catheter. Instantaneous soft tissue imaging provides immediate feedback on safety.
Collapse
|
17
|
El-Sharkawy AMM, Qian D, Bottomley PA. The performance of interventional loopless MRI antennae at higher magnetic field strengths. Med Phys 2008; 35:1995-2006. [PMID: 18561676 DOI: 10.1118/1.2905027] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Interventional, "loopless antenna" MRI detectors are currently limited to 1.5 T. This study investigates whether loopless antennae offer signal-to-noise ratio (SNR) and field-of-view (FOV) advantages at higher fields, and whether device heating can be controlled within safe limits. The absolute SNR performance of loopless antennae from 0.5 to 5 T is investigated both analytically, using electromagnetic (EM) dipole antenna theory, and numerically with the EM method of moments, and found to vary almost quadratically with field strength depending on the medium's electrical properties, the noise being dominated by direct sample conduction losses. The prediction is confirmed by measurements of the absolute SNR of low-loss loopless antennae fabricated for 1.5, 3, and 4.7 T, immersed in physiologically comparable saline. Gains of 3.8 +/- 0.2- and 9.7 +/- 0.3-fold in SNR, and approximately 10- and 50-fold gains in the useful FOV area are observed at 3 and 4.7 T, respectively, compared to 1.5 T. Heat testing of a 3 T biocompatible nitinol-antenna fabricated with a redesigned decoupling circuit shows maximum heating of approximately 1 degrees C for MRI operating at high MRI exposure levels. Experiments in the rabbit aorta confirm the SNR and FOV advantages of the 3 T antenna versus an equivalent commercial 1.5 T device in vivo. This work is the first to study the performance of experimental internal MRI detectors above 1.5 T. The large SNR and FOV gains realized present a major opportunity for high-resolution imaging of vascular pathology and MRI-guided intervention.
Collapse
Affiliation(s)
- AbdEl-Monem M El-Sharkawy
- Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21287, USA
| | | | | |
Collapse
|
18
|
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.
Collapse
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.
| |
Collapse
|
19
|
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.
| |
Collapse
|
20
|
Rickers C, Kraitchman D, Fischer G, Kramer HH, Wilke N, Jerosch-Herold M. Cardiovascular interventional MR imaging: a new road for therapy and repair in the heart. Magn Reson Imaging Clin N Am 2005; 13:465-79. [PMID: 16084413 DOI: 10.1016/j.mric.2005.04.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Over the last 5 years, interventional MR imaging has been fertile ground for research. Real-time MR imaging, combined with recent advances in other MR imaging modalities such as perfusion imaging and intravascular imaging, has opened up new paths for cardiac therapy. The recent reports on cardiac stem cell therapy guided and monitored by MR imaging suggest that we are already seeing the establishment of an important role for cardiac MR imaging in cardiac restoration. The collaborative effort from a multidisciplinary team of basic biologists, engineers, and clinicians will refine stem cell incubation and labeling for MR-guided transcatheter endomyocardial injections, and this in turn may facilitate new studies in humans. Several groups have demonstrated in animal studies the feasibility of MR-guided catheter interventions for the treatment of congenital heart disease and arrythmia therapy. Hence, applications in humans remain the challenge for the next years. Although there have been first reports of cardiac catheterizations in humans by combined use of x-ray fluoroscopy and MR imaging, there are no reports in the literature suggesting that active tracking methods by MR imaging have been applied to humans. Safety issues (namely, heating of catheters and wires) hamper clinical use, particularly in infants and children. Current reports are promising that these limitations will be overcome in the near future and will eventually reduce x-ray usage during catheterization. In its current state, cardiac MR imaging offers a unique opportunity to investigate new therapeutic strategies for the treatment of congenital and acquired heart disease.
Collapse
Affiliation(s)
- Carsten Rickers
- Department of Pediatric Cardiology, University Hospital Schleswig-Holstein, Campus Kiel, Brunswiker Strasse 10, 24105 Kiel, Germany.
| | | | | | | | | | | |
Collapse
|
21
|
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.
Collapse
Affiliation(s)
- Cengizhan Ozturk
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | | | | | | |
Collapse
|
22
|
Abstract
The motivations for developing MR-guided minimally invasive therapy include its excellent soft tissue contrast, tomographic imaging in any direction (as opposed to projection imaging as in fluoroscopy), the absence of ionizing radiation,the abundance of contrast mechanisms (including bright blood pulse sequences that lead to excellent vessel conspicuity without exogenous contrast agent injection), the ability to obtain physiologic information such as perfusion, and an overall excellent safety profile. The main pulse sequences used today for interventional MR imaging are T1/T2-weighted FISP and TrueFISP, T2-weighted turbo spin-echo, and T1-weighted FLASH. The specific clinical question, the underlying pathophysiology,and the procedure to be performed dictate which sequence is used. Each of these sequences has been written to acquire data in conventional rectilinear trajectories, radial k-space paths, or even spirals. In many ways, the questions being researched in interventional MR imaging have been dictated by the primary issues in greatest need of resolution or that most directly facilitate new clinical development. A decade ago, research focused on exploration of new scan strategies for contrast and temporal resolution. Advancements in the last decade have made it possible to acquire and display greater than 10 images per second in realtime with millimeter resolution in all three directions. This temporal and spatial resolution is considered high enough to guide most interventions. With this capability, other research has focused on instrument tracking. The field has gone from the capability to track a single coil and superimpose it on a previously acquired roadmap to systems that follow, adapt, and provide high-resolution images due to the advent of multichannel receiver systems, improved graphics, higher processor speeds, and increases in speed and quantity of memory. Hence, instruments can be reliably identified and tracked and the information can be used to update pulse sequence parameters in real time, thereby opening new opportunities for interventional MR imaging that extend from biopsy and thermal therapy to image-guided vascular and cardiac procedures. Today, we see such issues as RF heating of wires used for device localization and the noise generated by rapid switching of MR gradients being significant obstacles yet to overcome to allow the full strength of MR-guided interventions to be realized clinically. It is anticipated that these topics will emerge as critical concepts in the next decade of interventional MR imaging research.
Collapse
Affiliation(s)
- Jamal J Derakhshan
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | | |
Collapse
|
23
|
Raman VK, Karmarkar PV, Guttman MA, Dick AJ, Peters DC, Ozturk C, Pessanha BSS, Thompson RB, Raval AN, DeSilva R, Aviles RJ, Atalar E, McVeigh ER, Lederman RJ. Real-time magnetic resonance-guided endovascular repair of experimental abdominal aortic aneurysm in swine. J Am Coll Cardiol 2005; 45:2069-77. [PMID: 15963411 PMCID: PMC1317097 DOI: 10.1016/j.jacc.2005.03.029] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 02/20/2005] [Accepted: 03/01/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVES This study tested the hypotheses that endografts can be visualized and navigated in vivo solely under real-time magnetic resonance imaging (rtMRI) guidance to repair experimental abdominal aortic aneurysms (AAA) in swine, and that MRI can provide immediate assessment of endograft apposition and aneurysm exclusion. BACKGROUND Endovascular repair for AAA is limited by endoleak caused by inflow or outflow malapposition. The ability of rtMRI to image soft tissue and flow may improve on X-ray guidance of this procedure. METHODS Infrarenal AAA was created in swine by balloon overstretch. We used one passive commercial endograft, imaged based on metal-induced MRI artifacts, and several types of homemade active endografts, incorporating MRI receiver coils (antennae). Custom interactive rtMRI features included color coding the catheter-antenna signals individually, simultaneous multislice imaging, and real-time three-dimensional rendering. RESULTS Eleven repairs were performed solely using rtMRI, simultaneously depicting the device and soft-tissue pathology during endograft deployment. Active devices proved most useful. Intraprocedural MRI provided anatomic confirmation of stent strut apposition and functional corroboration of aneurysm exclusion and restoration of laminar flow in successful cases. In two cases, there was clear evidence of contrast accumulation in the aneurysm sac, denoting endoleak. CONCLUSIONS Endovascular AAA repair is feasible under rtMRI guidance. Active endografts facilitate device visualization and complement the soft tissue contrast afforded by MRI for precise positioning and deployment. Magnetic resonance imaging also permits immediate post-procedural anatomic and functional evaluation of successful aneurysm exclusion.
Collapse
Affiliation(s)
| | - Parag V. Karmarkar
- From the Cardiovascular Branch and the
- Laboratory of Cardiac Energetics, Division of Intramural Research, National Heart, Lung, and Blood Institute, Bethesda, Maryland; and the
| | - Michael A. Guttman
- Laboratory of Cardiac Energetics, Division of Intramural Research, National Heart, Lung, and Blood Institute, Bethesda, Maryland; and the
| | | | - Dana C. Peters
- Laboratory of Cardiac Energetics, Division of Intramural Research, National Heart, Lung, and Blood Institute, Bethesda, Maryland; and the
| | | | | | - Richard B. Thompson
- Laboratory of Cardiac Energetics, Division of Intramural Research, National Heart, Lung, and Blood Institute, Bethesda, Maryland; and the
| | | | | | | | - Ergin Atalar
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland. Supported by NIH Z01-HL005062-01CVB (to Dr. Lederman). Drs. Raman and Karmarkar contributed equally to this work
| | - Elliot R. McVeigh
- Laboratory of Cardiac Energetics, Division of Intramural Research, National Heart, Lung, and Blood Institute, Bethesda, Maryland; and the
| | - Robert J. Lederman
- From the Cardiovascular Branch and the
- Reprint requests and correspondence: Dr. Robert J. Lederman, Cardiovascular Branch, Clinical Research Program, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10, Room 2c713, Bethesda, Maryland 20892-1538. E-mail:
| |
Collapse
|
24
|
Dick AJ, Raman VK, Raval AN, Guttman MA, Thompson RB, Ozturk C, Peters DC, Stine AM, Wright VJ, Schenke WH, Lederman RJ. Invasive human magnetic resonance imaging: feasibility during revascularization in a combined XMR suite. Catheter Cardiovasc Interv 2005; 64:265-74. [PMID: 15736247 PMCID: PMC1317610 DOI: 10.1002/ccd.20302] [Citation(s) in RCA: 50] [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: 11/08/2022]
Abstract
We tested the feasibility and safety of invasive magnetic resonance imaging (MRI) during peripheral angioplasty. Real-time MRI can image soft tissue and may potentially guide therapeutic procedures without ionizing radiation or nephrotoxic contrast. MRI-guided diagnostic catheterization has been described recently, but safe and conspicuous catheter devices are not widely available. An active guidewire, which serves as an MRI receiver antenna, might be useful to guide catheterization or even to image atheroma. We describe a combined interventional suite offering both X-ray fluoroscopy and real-time MRI. We used a 0.030'' active guidewire receiver coil for invasive MRI after X-ray lesion traversal in patients undergoing percutaneous iliofemoral artery revascularization. Intravascular MRI was compared with noninvasive MRI, X-ray angiography, and intravascular ultrasound (IVUS). Seven eligible patients consented to participate, but three were excluded because of lengthy revascularization procedures. Four remaining patients safely underwent combined X-ray fluoroscopy and real-time magnetic resonance imaging (XMR) transport, continuous monitoring, and all imaging modalities. There was no device dislodgment, contamination or evidence of heating. The intravascular MRI coil was well visualized except at the tip, but did not provide superior mural imaging compared with IVUS. Therefore, because an adequate safety and workflow experience was obtained, enrollment was terminated after only four subjects. Invasive MRI is feasible and apparently safe during peripheral angioplasty. Patients can safely be transported and monitored in an XMR interventional suite. An active quarter-wavelength guidewire coil does not provide superior imaging compared with IVUS, but provides satisfactory guidewire visualization. These tools may prove useful for advanced therapeutic procedures in the future.
Collapse
Affiliation(s)
- Alexander J. Dick
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Venkatesh K. Raman
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Amish N. Raval
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | | | - Richard B. Thompson
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Cengizhan Ozturk
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Dana C. Peters
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Annette M. Stine
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Victor J. Wright
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - William H. Schenke
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Robert J. Lederman
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland
- *Correspondence to: Dr. Robert J. Lederman, 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. E-mail:
| |
Collapse
|
25
|
Poirier-Quinot M, Ginefri JC, Ledru F, Fornes P, Darrasse L. Preliminary ex vivo 3D microscopy of coronary arteries using a standard 1.5 T MRI scanner and a superconducting RF coil. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2005; 18:89-95. [PMID: 15711851 DOI: 10.1007/s10334-004-0097-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 12/01/2004] [Accepted: 12/01/2004] [Indexed: 11/28/2022]
Abstract
This paper presents the feasibility of three-dimensional (3D) magnetic resonance (MR) histology of atheromatous coronary lesions in the entire human heart ex vivo using a standard 1.5 T scanner and a 12 mm high-temperature superconducting (HTS) surface coil. The HTS coil was a five-turn transmission-line resonator operated at 77 K, affording a signal-to-noise ratio (SNR) gain of about ninefold as compared to a similar, room-temperature copper coil. Local microscopy at the surface of an explanted, entire heart was achieved by a 3D spoiled gradient echo sequence and assessed by comparison with conventional histology. One hundred and twenty four adjacent cross sections of the coronary artery, with voxels of 59 x 59 x 100 microm3 and an SNR of about 20, were obtained in 25 min. Consecutive data sets were combined to reconstruct extended views along the artery. Compared to histology, MR microscopy allowed precise nondestructive 3D depiction of the architecture of the atheromatous plaques. This is the first report of microscopic details (less than 10(-3) mm3 voxels) of diseased arteries obtained in an entire human heart preserving the arterial integrity and the spatial geometry of atheroma. This noninvasive microscopy approach using a HTS surface coil might be applied in vivo to study the architecture and components of superficial human structures, using routine MR scanners.
Collapse
|
26
|
Celik H, Eryaman Y, Altintaş A, Abdel-Hafez IA, Atalar E. Evaluation of internal MRI coils using ultimate intrinsic SNR. Magn Reson Med 2004; 52:640-9. [PMID: 15334585 DOI: 10.1002/mrm.20200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The upper bounds of the signal-to-noise ratio (also known as the "ultimate intrinsic signal-to-noise ratio" (UISNR)) for internal and external coils were calculated. In the calculation, the body was modeled as a dielectric cylinder with a small coaxial cylindrical cavity in which internal coils could be placed. The calculated UISNR values can be used as reference solutions to evaluate the performance of internal MRI coils. As examples, we evaluated the performance of a loopless antenna and an endourethral coil design by comparing their ISNR with the UISNR.
Collapse
Affiliation(s)
- Haydar Celik
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
| | | | | | | | | |
Collapse
|
27
|
Current awareness in NMR in biomedicine. NMR IN BIOMEDICINE 2003; 16:510-517. [PMID: 14719526 DOI: 10.1002/nbm.806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
|