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Lefrançois W, Thiaudière E, Ben Hassen W, Sanchez S, Franconi JM, Miraux S. Fast whole-body magnetic resonance angiography in mice. Magn Reson Med 2011; 66:32-9. [DOI: 10.1002/mrm.22985] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 04/08/2011] [Accepted: 04/08/2011] [Indexed: 11/08/2022]
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2
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Wu CW, Chuang KH, Wai YY, Wan YL, Chen JH, Liu HL. Vascular space occupancy-dependent functional MRI by tissue suppression. J Magn Reson Imaging 2008; 28:219-26. [PMID: 18581345 DOI: 10.1002/jmri.21410] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
PURPOSE To measure the cerebral blood volume (CBV) dynamics during neural activation, a novel technique named vascular space occupancy (VASO)-based functional MRI (fMRI) was recently introduced for noninvasive CBV detection. However, its application is limited because of its low contrast-to-noise ratio (CNR) due to small signal change from the inverted blood. MATERIALS AND METHODS In this study a new approach-VASO with tissue suppression (VAST)-is proposed to enhance CNR. This technique is compared with VASO and blood oxygenation level-dependent (BOLD) fMRI in block-design and event-related visual experiments. RESULTS Based on acquired T(1) maps, 75.3% of the activated pixels detected by VAST are located in the cortical gray matter. Temporal characteristics of functional responses obtained by VAST were consistent with that of VASO. Although the baseline signal was decreased by the tissue suppression, the CNR of VAST was about 43% higher than VASO. CONCLUSION With the improved sensitivity, VAST fMRI provides a useful alternative for mapping the spatial/temporal features of regional CBV changes during brain activation. However, the technical imperfectness of VAST, such as the nonideal inversion efficiency and physiological contaminations, limits its application to precise CBV quantification.
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Affiliation(s)
- Changwei W Wu
- Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, National Taiwan University, Section 4 No. 1 Roosevelt Road, Taipei, Taiwan
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3
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Attia C, Abdulrazzaq S, Huet L, Saint-James H, Beuf O, Farhat F, Douek P. Feasibility of stent-graft placement with real-time MR fluoroscopy in a nonrigid aortic phantom. J Vasc Interv Radiol 2008; 19:1354-60. [PMID: 18725099 DOI: 10.1016/j.jvir.2008.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 05/21/2008] [Accepted: 06/02/2008] [Indexed: 11/27/2022] Open
Abstract
PURPOSE To evaluate the feasibility of using real-time magnetic resonance (MR) fluoroscopic guidance to place a stent-graft mounted on a guide wire in a nonrigid aortic phantom. MATERIALS AND METHODS Real-time fast low-angle shot and true fast imaging with steady-state precession MR imaging sequences were used for device tracking. A modified fiber-optic guide wire and catheter embedded with titanium oxide in predefined positions were used for navigation in a homemade silicone thoracic aortic phantom. RESULTS Susceptibility artifacts caused by the modified guide wire and catheters mounted in the descending thoracic aorta of the phantom were found to enable adequate determination of the guide wire position in relation to the surrounding anatomy and to cause no image distortion. Real-time MR imaging enabled visualization of both the vessel lumen and the delivery system with the mounted stent-graft, providing an image quality sufficient for successful localization of the lesion and deployment of the stent-graft. CONCLUSIONS The results of this study prove the possibility of passive guidance in MR imaging-guided stent placement in vitro. The modified guide wire can be used with interventional commercial catheters and recent implant devices with selective tracking in the surrounding anatomy.
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Affiliation(s)
- Cherif Attia
- CREATIS-LRMN, UMR 5515, U630 INSERM, Cardiovascular Lyon University Hospital, Louis Pradel, 69394 Lyon Cedex 03, France
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4
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Rapid passive MR catheter visualization for endovascular therapy using nonsymmetric truncated k-space sampling strategies. Magn Reson Imaging 2008; 26:293-303. [DOI: 10.1016/j.mri.2007.08.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Revised: 08/02/2007] [Accepted: 08/08/2007] [Indexed: 11/20/2022]
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5
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Edelman RR, Storey P, Dunkle E, Li W, Carrillo A, Vu A, Carroll TJ. Gadolinium-enhanced off-resonance contrast angiography. Magn Reson Med 2007; 57:475-84. [PMID: 17326177 DOI: 10.1002/mrm.21175] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We describe a novel physical basis and methodology for gadolinium (Gd)-enhanced MRA, which we call "off-resonance contrast angiography" (ORCA). Unlike standard contrast-enhanced (CE) MR angiography (MRA), ORCA contrast depends not on T(1) but on Gd-induced shifts in intravascular resonance frequency due to the bulk magnetic susceptibility (BMS) effects of Gd. The method was tested at 3 Tesla in phantoms with a range of dilutions of Gd-DTPA and ultrasmall iron oxide contrast agent (CA). With the use of ORCA, complete background suppression was obtained without image subtraction. As a result, catheters filled with various Gd dilutions proved to be highly conspicuous in ORCA projection images. This feature may make ORCA particularly attractive for passive catheter tracking during MR-guided endovascular procedures. Gd-induced intravascular frequency shifts were measured in human subjects and found to be in the expected range. ORCA was used to create angiograms of forearm veins that were comparable in quality to standard CE-MRA. In addition, ORCA images of the extracranial carotid bifurcation were successfully acquired during intravenous contrast administration. However, significant technical restrictions also exist, including a dependence on vessel orientation with respect to B(0), and sensitivity to static field inhomogeneities. Further study is needed to determine the practicality and potential clinical utility of this method.
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Affiliation(s)
- Robert R Edelman
- Department of Radiology, Evanston Northwestern Healthcare and Northwestern University School of Medicine, Evanston, Illinois 60201, USA.
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6
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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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7
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Bakker CJG, Peters NHGM, Vincken KL, van der Bom M, Seppenwoolde JH. Factors affecting the effectiveness of a projection dephaser in 2D gradient-echo imaging. Phys Med Biol 2007; 52:3847-57. [PMID: 17664581 DOI: 10.1088/0031-9155/52/13/013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Projection dephasers are often used for background suppression and dynamic range improvement in thick-slab 2D imaging in order to promote the visibility of subslice structures, e.g., blood vessels and interventional devices. In this study, we explored the factors that govern the effectiveness of a projection dephaser by simulations and phantom experiments. This was done for the ideal case of a single subslice hyper- or hypointensity against a uniform background in the absence of susceptibility effects. Simulations and experiments revealed a pronounced influence of the slice profile, the nominal flip angle and the TE and TR of the acquisition, the size, intraslice position and MR properties of the subslice structure, and T(1) of the background. The complexity of the ideal case points to the necessity of additional explorations when considering the use of projection dephasers under less ideal conditions, e.g., in the presence of tissue heterogeneities and susceptibility gradients.
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Affiliation(s)
- Chris J G Bakker
- Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, The Netherlands.
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8
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Huegli RW, Aschwanden M, Scheffler K, Bilecen D. Fluoroscopic Contrast-Enhanced MR Angiography with a Magnetization-Prepared Steady-State Free Precession Technique in Peripheral Arterial Occlusive Disease. AJR Am J Roentgenol 2006; 187:242-7. [PMID: 16794183 DOI: 10.2214/ajr.05.1183] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The objective of our study was to evaluate the feasibility of intraarterial (IA) near-real-time contrast-enhanced MR angiography (CE-MRA) with a frame rate of 1.3 frames per second in seven patients with lower extremity peripheral arterial occlusive disease (PAOD). For optimized background suppression, a modified 2D steady-state free precession (SSFP) technique with magnetization preparation and mask subtraction was developed. The femoropopliteal and infrapopliteal arteries were covered in two separate steps. Acceptable contrast-to-noise ratios were obtained, and road maps were reconstructed from the same data set. CONCLUSION Mastering IA near-real-time CE-MRA, including road map reconstruction, with an SSFP technique in the lower extremity of patients with PAOD is an important building block toward successfully performing endovascular catheter MR-guided interventions.
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Affiliation(s)
- Rolf W Huegli
- Department of Radiology, University Hospital of Basel, Petersgraben 4, 4031 Basel, Switzerland.
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9
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Mekle R, Hofmann E, Scheffler K, Bilecen D. A polymer-based MR-compatible guidewire: a study to explore new prospects for interventional peripheral magnetic resonance angiography (ipMRA). J Magn Reson Imaging 2006; 23:145-55. [PMID: 16374877 DOI: 10.1002/jmri.20486] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To introduce a newly developed polymer-based and magnetic resonance (MR)-compatible guidewire and to explore its capabilities with respect to interventional peripheral magnetic resonance angiography (ipMRA) in a flow phantom. MATERIALS AND METHODS The guidewire is based on a polyetheretherketone (PEEK) polymer core, and small iron particles are embedded in its coating. A passive device tracking technique was designed utilizing a susceptibility artifact induced by the wire in images acquired with a balanced steady-state free precession (b-SSFP) sequence using small flip angles. The position of the guidewire tip was determined from image intensity maxima and overlayed onto a roadmap in near real-time. Guidewire tracking and balloon angioplasty of an artificial stenosis were attempted in two configurations of a flow phantom. RESULTS Successful passive guidewire tracking was performed for all phantom configurations. Robustness and accuracy of the tracking technique were sufficient for phantom studies. A balloon catheter was placed into the stenosis using the guidewire under complete MR guidance, and subsequent balloon angioplasty yielded improved flow conditions. CONCLUSION The new guidewire is well-suited for clinical application due to an absence of the risk of core fracture and its atraumatic flexible tip. It opens novel prospects for the realization of ipMRA in humans that need to be explored in further studies.
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Affiliation(s)
- Ralf Mekle
- MR-Physics, University of Basel/University Hospital, Basel, Switzerland.
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10
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Abstract
In this work gradient dephasing is treated as a mechanism for manipulating contrast in otherwise conventional MR images. The paper provides a theoretical and experimental framework for this approach. It starts from the observation that dephasing gradients invoke a shift in k-space. From this it is inferred that the effects of in-plane and through-plane dephasing can be systematically explored in the context of any given imaging experiment by sampling k-space more widely and densely than dictated by the field of view (FOV) and the spatial resolution of the desired images. The oversampled k-space allows an ensemble of lower-resolution dephased images to be reconstructed in which the degree and direction of dephasing are determined by the off-center position of the reconstruction window. The efficacy of this approach is demonstrated for standard gradient-echo acquisitions in a phantom. The results indicate the potential of the proposed methodology for evaluating 3D image data and optimizing gradient dephasing in applications that rely on the exploitation of partial volume and susceptibility effects (e.g., tracking interventional devices and tracing magnetically labeled substances).
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Affiliation(s)
- Chris J G Bakker
- Department of Radiology, University Medical Center Utrecht, The Netherlands.
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Draper JN, Lauzon ML, Frayne R. Passive catheter visualization in magnetic resonance–guided endovascular therapy using multicycle projection dephasers. J Magn Reson Imaging 2006; 24:160-7. [PMID: 16758467 DOI: 10.1002/jmri.20619] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To improve upon the conventional projection dephaser (PD) method of background suppression and evaluate the use of multicycle projection dephasers to improve catheter conspicuity in background-suppressed MR images. MATERIALS AND METHODS Passive visualization of endovascular catheters in MR images is compared using two background suppression techniques: 1) the conventional PD method and 2) the multicycle PD method. Contrast-filled 4-French (1.3 mm) catheters were imaged in homogeneous and heterogeneous phantoms, and in the common carotid artery of a canine using a modified spoiled gradient echo imaging sequence. We used catheter-to-background contrast (ranging from -100% to 100%) as the metric to compare background suppression techniques. RESULTS In the homogeneous and heterogeneous phantoms, the contrast was -6.9% (catheter darker than background) and 15.0%, respectively, using the conventional PD method, and 50.6% and 44.0%, respectively, using the multicycle PD method. In the canine carotid artery, the contrast was -3.1% using the conventional PD method and 53.0% using the multicycle PD method. CONCLUSION This work shows that multicycle projection dephasers improve catheter conspicuity over the conventional PD method. The multicycle PD method has potential for use in guiding endovascular procedures.
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Affiliation(s)
- Jonathan N Draper
- Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada
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Tsekos NV, Atalar E, Li D, Omary RA, Serfaty JM, Woodard PK. Magnetic resonance imaging-guided coronary interventions. J Magn Reson Imaging 2004; 19:734-49. [PMID: 15170780 DOI: 10.1002/jmri.20071] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Magnetic resonance imaging (MRI) guidance for coronary interventions offers potential advantages over conventional x-ray angiography. Advantages include the use of nonionizing radiation, combined assessment of anatomy and function, and three-dimensional assessment of the coronary arteries leading to the myocardium. These advantages have prompted a series of recent studies in this field. Real-time coronary MR angiography, with low-dose catheter-directed intraarterial (IA) infusion of contrast media, has achieved in-plane spatial resolution as low as 0.8 x 0.8 mm2 and temporal resolution as short as 130 msec per image. Catheter-based IA injection of contrast agent has proven useful in the collection of multislice and three-dimensional images, not only for coronary intervention guidance, but also in the assessment of regional myocardial perfusion fed by the affected vessel. Actively visible guidewires and guiding catheters, based on the loopless antenna concept, have been effectively used to negotiate tortuous coronary vessels during catheterization, permitting placement of coronary angioplasty balloon catheters. Passive tracking approaches have been used to image contrast agent-filled coronary catheters and to place susceptibility-based endovascular stents. Although the field is in its infancy, these early results demonstrate the feasibility for performing MRI-guided coronary interventions. Although further methodological and technical developments are required before these methods become clinically applicable, we anticipate that MRI someday will be included in the armamentarium of techniques used to diagnose and treat coronary artery disease.
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Affiliation(s)
- Nikolaos V Tsekos
- Cardiovascular Imaging Laboratory, Mallinckrodt Institute of Radiology, Washington University, St. Louis, Missouri 63110, USA.
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13
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Green JD, Omary RA, Schirf BE, Tang R, Li D. Catheter-directed contrast-enhanced coronary MR angiography in swine using magnetization-prepared True-FISP. Magn Reson Med 2003; 50:1317-21. [PMID: 14648582 DOI: 10.1002/mrm.10642] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Contrast-enhanced (CE) coronary magnetic resonance angiography (MRA) following intraarterial (IA) injection of contrast agent was compared using two sequences in swine: magnetization-prepared fast imaging with steady-state precession (True-FISP), and magnetization-prepared fast low-angle shot (FLASH). Thick-slice projection images were acquired with submillimeter in-plane spatial resolution (0.9 x 0.8 mm(2)). The magnetization-preparation scheme provided a clear delineation of the major coronary arteries with excellent background suppression. The True-FISP acquisition resulted in an increase in signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) by approximately a factor of 2 over FLASH (P < 0.05). Magnetization-prepared True-FISP is a promising technique for catheter-directed CE thick-slice projection coronary MRA.
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Affiliation(s)
- Jordin D Green
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
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Quick HH, Kuehl H, Kaiser G, Hornscheidt D, Mikolajczyk KP, Aker S, Debatin JF, Ladd ME. Interventional MRA using actively visualized catheters, TrueFISP, and real-time image fusion. Magn Reson Med 2003; 49:129-37. [PMID: 12509828 DOI: 10.1002/mrm.10334] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An integrated system for performing interventional magnetic resonance angiography (MRA) with actively visualized instruments and real-time image fusion was implemented on a 1.5 T scanner. True fast imaging with steady precession (TrueFISP) imaging provided high acquisition speed paired with high signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for the simultaneous visualization of active instruments and arterial morphology. The system enabled simultaneous image reconstruction and image postprocessing of multiple receiver channels, with subsequent image fusion display in real time. Optional interleaved image acquisition in two planes provided additional important information for biplanar instrument guidance. Various vascular interventions, including selective catheterization and subsequent selective MRA of the abdominal aorta, renal arteries, superior mesenteric artery (SMA), hepatic artery, and aortic arch, were performed on 10 pigs under MR guidance. In terms of instrument contrast, image acquisition, reconstruction, and fusion speed, the setup represents a powerful platform for performing interventional MRA procedures.
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Affiliation(s)
- Harald H Quick
- Department of Diagnostic and Interventional Radiology, University Hospital Essen, Essen, Germany.
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15
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Green JD, Omary RA, Finn JP, Chung YC, Tang R, Li Y, Vasireddy S, Li D. Two- and three-dimensional MR coronary angiography with intraarterial injections of contrast agent in dogs: a feasibility study. Radiology 2003; 226:272-7. [PMID: 12511701 DOI: 10.1148/radiol.2261011848] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Magnetic resonance (MR) images of coronary arteries were acquired with an inversion recovery-prepared technique after intraarterial injection of contrast material in five dogs. Real-time two-dimensional projection images were obtained with a temporal resolution of 3 frames per second. Three-dimensional electrocardiographically triggered high-spatial-resolution images were obtained with a fraction of the contrast agent required for intravenous injections. Background tissues were adequately suppressed in all images. On the basis of this experimental data, the optimal contrast agent concentration for two-dimensional real-time projection imaging was 6%. This preliminary work shows that contrast material-enhanced MR angiography with intraarterial injections is feasible with the proposed techniques.
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Affiliation(s)
- Jordin D Green
- Department of Radiology, Northwestern University Medical School, 448 E Ontario St, Suite 700, Chicago, IL 60611, USA
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Green JD, Omary RA, Finn JP, Tang R, Li Y, Carr J, Li D. Passive catheter tracking using MRI: comparison of conventional and magnetization-prepared FLASH. J Magn Reson Imaging 2002; 16:104-9. [PMID: 12112510 DOI: 10.1002/jmri.10132] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To compare a magnetization-prepared gradient-echo (GRE) sequence with a conventional GRE sequence for visualizing contrast agent-filled catheters. MATERIALS AND METHODS Passive visualization of endovascular catheters using MRI was compared between two imaging sequences: 1) inversion recovery (IR)-fast low angle shot (FLASH), and 2) conventional FLASH. Two-dimensional projection images of the catheters filled with 4% diluted contrast agent in a phantom and the aorta of swine were obtained with each sequence with a temporal resolution of two frames per second. We compared background suppression and catheter visibility using the catheter-to-background signal ratio and the ratings of two radiologists. RESULTS In the phantom, IR-FLASH allowed for a 200% increase in catheter-to-background ratio (p < 0.01) and improved depiction of catheters over conventional FLASH. In swine, the IR-FLASH images showed a statistically significant improvement of 80% (p < 0.001) over conventional FLASH in all comparisons of the catheter-to-background signal ratio, and an improvement of 160% (p < 0.05) in comparison with the radiologists' observations. CONCLUSION This study shows that IR-FLASH is a better technique for passive tracking of contrast agent-filled catheters than conventional FLASH.
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Affiliation(s)
- Jordin D Green
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
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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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Guttman MA, Lederman RJ, Sorger JM, McVeigh ER. Real-time volume rendered MRI for interventional guidance. J Cardiovasc Magn Reson 2002; 4:431-42. [PMID: 12549231 PMCID: PMC2570028 DOI: 10.1081/jcmr-120016382] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Volume renderings from magnetic resonance imaging data can be created and displayed in real-time with user interactivity. This can provide continuous 3D feedback to assist in guiding an interventional procedure. A system is presented which can produce real-time volume renderings from 2D multi-slice or 3D MR pulse sequences. Imaging frame rates up to 30 per second have been demonstrated with a latency of approximately one-third of a second, depending on the image matrix size. Several interactive capabilities have been implemented to enhance visualization such as cut planes, individual channel scaling and color highlighting, view sharing, saturation preparation, complex subtraction, gating control, and choice of alpha blending or MIP rendering. The system is described and some interventional application examples are shown. To view movies of some of the examples, enter the following address into a web browser: http://nhlbi.nih.gov/labs/papers/lce/guttman/rtvolmri/index/htm.
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Affiliation(s)
- Michael A Guttman
- Laboratory of Cardiac Energetics, National Institutes of Health, National Heart, Lung and Blood Institute, 10 Center Dr., Building 10, Room B1D416, Bethesda, MD 20892-1061, USA.
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van der Weide R, Bakker CJ, Viergever MA. Localization of intravascular devices with paramagnetic markers in MR images. IEEE TRANSACTIONS ON MEDICAL IMAGING 2001; 20:1061-1071. [PMID: 11686441 DOI: 10.1109/42.959303] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Magnetic resonance imaging (MRI) offers potential advantages over conventional X-ray techniques for guiding and evaluating intravascular interventions. The development of methods to safely and robustly localize and track devices under MRI guidance is mandatory to enable automatic scan plane adaptation so as to exploit the three-dimensional imaging capabilities of the MRI scanner. With regard to the issue of radiofrequency-induced heating, passive approaches to catheter tracking are inherently safe. These techniques visualize intravascular devices by exploiting the susceptibility artifacts associated with the devices. To promote conspicuity, the devices are equipped with paramagnetic markers. This paper introduces a method to enable automatic localization of devices by its ability to recognize markers in two-dimensional MR images. The method requires a coarse segmentation of the vasculature of interest, and consists of two steps. First, it performs a series of postprocessing operations including calculation of the winding number image and of the Laplacian image to detect marker candidates in the image. Second, the device is localized by matching the detected pattern of candidates to the known distance template of the device markers. Results of an animal experiment and of a clinical application are demonstrated. Validation in phantom experiments shows that the method is able to localize the device in 95% of the cases.
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Affiliation(s)
- R van der Weide
- Image Sciences Institute, Department of Radiology, University Medical Center Utrecht, The Netherlands.
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