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Özen AC, Russe MF, Lottner T, Reiss S, Littin S, Zaitsev M, Bock M. RF-induced heating of interventional devices at 23.66 MHz. MAGMA (NEW YORK, N.Y.) 2023:10.1007/s10334-023-01099-7. [PMID: 37195365 PMCID: PMC10386938 DOI: 10.1007/s10334-023-01099-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/29/2023] [Accepted: 05/04/2023] [Indexed: 05/18/2023]
Abstract
OBJECTIVE Low-field MRI systems are expected to cause less RF heating in conventional interventional devices due to lower Larmor frequency. We systematically evaluate RF-induced heating of commonly used intravascular devices at the Larmor frequency of a 0.55 T system (23.66 MHz) with a focus on the effect of patient size, target organ, and device position on maximum temperature rise. MATERIALS AND METHODS To assess RF-induced heating, high-resolution measurements of the electric field, temperature, and transfer function were combined. Realistic device trajectories were derived from vascular models to evaluate the variation of the temperature increase as a function of the device trajectory. At a low-field RF test bench, the effects of patient size and positioning, target organ (liver and heart) and body coil type were measured for six commonly used interventional devices (two guidewires, two catheters, an applicator and a biopsy needle). RESULTS Electric field mapping shows that the hotspots are not necessarily localized at the device tip. Of all procedures, the liver catheterizations showed the lowest heating, and a modification of the transmit body coil could further reduce the temperature increase. For common commercial needles no significant heating was measured at the needle tip. Comparable local SAR values were found in the temperature measurements and the TF-based calculations. CONCLUSION At low fields, interventions with shorter insertion lengths such as hepatic catheterizations result in less RF-induced heating than coronary interventions. The maximum temperature increase depends on body coil design.
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Affiliation(s)
- Ali Caglar Özen
- Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Maximilian Frederik Russe
- Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas Lottner
- Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Simon Reiss
- Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian Littin
- Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Maxim Zaitsev
- Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Bock
- Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Schmidt VF, Arnone F, Dietrich O, Seidensticker M, Armbruster M, Ricke J, Kazmierczak PM. Artifact reduction of coaxial needles in magnetic resonance imaging-guided abdominal interventions at 1.5 T: a phantom study. Sci Rep 2021; 11:22963. [PMID: 34824361 PMCID: PMC8617285 DOI: 10.1038/s41598-021-02434-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 11/10/2021] [Indexed: 11/12/2022] Open
Abstract
Needle artifacts pose a major limitation for MRI-guided interventions, as they impact the visually perceived needle size and needle-to-target-distance. The objective of this agar liver phantom study was to establish an experimental basis to understand and reduce needle artifact formation during MRI-guided abdominal interventions. Using a vendor-specific prototype fluoroscopic T1-weighted gradient echo sequence with real-time multiplanar acquisition at 1.5 T, the influence of 6 parameters (flip angle, bandwidth, matrix, slice thickness, read-out direction, intervention angle relative to B0) on artifact formation of 4 different coaxial MR-compatible coaxial needles (Nitinol, 16G–22G) was investigated. As one parameter was modified, the others remained constant. For each individual parameter variation, 2 independent and blinded readers rated artifact diameters at 2 predefined positions (15 mm distance from the perceived needle tip and at 50% of the needle length). Differences between the experimental subgroups were assessed by Bonferroni-corrected non-parametric tests. Correlations between continuous variables were expressed by the Bravais–Pearson coefficient and interrater reliability was quantified using the intraclass classification coefficient. Needle artifact size increased gradually with increasing flip angles (p = 0.002) as well as increasing intervention angles (p < 0.001). Artifact diameters differed significantly between the chosen matrix sizes (p = 0.002) while modifying bandwidth, readout direction, and slice thickness showed no significant differences. Interrater reliability was high (intraclass correlation coefficient 0.776–0.910). To minimize needle artifacts in MRI-guided abdominal interventions while maintaining optimal visibility of the coaxial needle, we suggest medium-range flip angles and low intervention angles relative to B0.
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Affiliation(s)
- Vanessa Franziska Schmidt
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany.
| | - Federica Arnone
- Department of Radiology Sciences, University of Palermo, Palermo, Italy
| | - Olaf Dietrich
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany
| | - Max Seidensticker
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany
| | - Marco Armbruster
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany
| | - Jens Ricke
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany
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Heidt T, Reiss S, Lottner T, Özen AC, Bode C, Bock M, von Zur Mühlen C. Magnetic resonance imaging for pathobiological assessment and interventional treatment of the coronary arteries. Eur Heart J Suppl 2020; 22:C46-C56. [PMID: 32368198 PMCID: PMC7189741 DOI: 10.1093/eurheartj/suaa009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
X-ray-based fluoroscopy is the standard tool for diagnostics and intervention in coronary artery disease. In recent years, computed tomography has emerged as a non-invasive alternative to coronary angiography offering detection of coronary calcification and imaging of the vessel lumen by the use of iodinated contrast agents. Even though currently available invasive or non-invasive techniques can show the degree of vessel stenosis, they are unable to provide information about biofunctional plaque properties, e.g. plaque inflammation. Furthermore, the use of radiation and the necessity of iodinated contrast agents remain unfavourable prerequisites. Magnetic resonance imaging (MRI) is a radiation-free alternative to X-ray which offers anatomical and functional imaging contrasts fostering the idea of non-invasive biofunctional assessment of the coronary vessel wall. In combination with molecular contrast agents that target-specific epitopes of the vessel wall, MRI might reveal unique plaque properties rendering it, for example, ‘vulnerable and prone to rupture’. Early detection of these lesions may allow for early or prophylactic treatment even before an adverse coronary event occurs. Besides diagnostic imaging, advances in real-time image acquisition and motion compensation now provide grounds for MRI-guided coronary interventions. In this article, we summarize our research on MRI-based molecular imaging in cardiovascular disease and feature our advances towards real-time MRI-based coronary interventions in a porcine model.
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Affiliation(s)
- Timo Heidt
- Department of Cardiology, Cardiology and Angiology I, Heart Center Freiburg University and Faculty of Medicine, Hugstetterstr. 55, 79106 Freiburg, Germany
| | - Simon Reiss
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Thomas Lottner
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Ali C Özen
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany.,German Cancer Consortium Partner Site Freiburg, German Cancer Research Center (DKFZ), Stefan-Meier-Str. 17, 79104 Freiburg, Germany
| | - Christoph Bode
- Department of Cardiology, Cardiology and Angiology I, Heart Center Freiburg University and Faculty of Medicine, Hugstetterstr. 55, 79106 Freiburg, Germany
| | - Michael Bock
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany
| | - Constantin von Zur Mühlen
- Department of Cardiology, Cardiology and Angiology I, Heart Center Freiburg University and Faculty of Medicine, Hugstetterstr. 55, 79106 Freiburg, Germany
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Functionalization of endovascular devices with superparamagnetic iron oxide nanoparticles for interventional cardiovascular magnetic resonance imaging. Biomed Microdevices 2019; 21:38. [DOI: 10.1007/s10544-019-0393-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Eibofner F, Martirosian P, Würslin C, Graf H, Syha R, Clasen S. Technical Note: MR-visualization of interventional devices using transient field alterations and balanced steady-state free precession imaging. Med Phys 2015; 42:6558-63. [PMID: 26520746 DOI: 10.1118/1.4932629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE In interventional magnetic resonance imaging, instruments can be equipped with conducting wires for visualization by current application. The potential of sequence triggered application of transient direct currents in balanced steady-state free precession (bSSFP) imaging is demonstrated. METHODS A conductor and a modified catheter were examined in water phantoms and in an ex vivo porcine liver. The current was switched by a trigger pulse in the bSSFP sequence in an interval between radiofrequency pulse and signal acquisition. Magnitude and phase images were recorded. Regions with transient field alterations were evaluated by a postprocessing algorithm. A phase mask was computed and overlaid with the magnitude image. RESULTS Transient field alterations caused continuous phase shifts, which were separated by the postprocessing algorithm from phase jumps due to persistent field alterations. The overlaid images revealed the position of the conductor. The modified catheter generated visible phase offset in all orientations toward the static magnetic field and could be unambiguously localized in the ex vivo porcine liver. CONCLUSIONS The application of a sequence triggered, direct current in combination with phase imaging allows conspicuous localization of interventional devices with a bSSFP sequence.
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Affiliation(s)
- Frank Eibofner
- Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076, Germany
| | - Petros Martirosian
- Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076, Germany
| | - Christian Würslin
- Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076, Germany
| | - Hansjörg Graf
- Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076, Germany
| | - Roland Syha
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen D-72076, Germany
| | - Stephan Clasen
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen D-72076, Germany
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Rube MA, Fernandez-Gutierrez F, Cox BF, Holbrook AB, Houston JG, White RD, McLeod H, Fatahi M, Melzer A. Preclinical feasibility of a technology framework for MRI-guided iliac angioplasty. Int J Comput Assist Radiol Surg 2014; 10:637-50. [PMID: 25102933 DOI: 10.1007/s11548-014-1102-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 07/02/2014] [Indexed: 11/25/2022]
Abstract
PURPOSE Interventional MRI has significant potential for image guidance of iliac angioplasty and related vascular procedures. A technology framework with in-room image display, control, communication and MRI-guided intervention techniques was designed and tested for its potential to provide safe, fast and efficient MRI-guided angioplasty of the iliac arteries. METHODS A 1.5-T MRI scanner was adapted for interactive imaging during endovascular procedures using new or modified interventional devices such as guidewires and catheters. A perfused vascular phantom was used for testing. Pre-, intra- and post-procedural visualization and measurement of vascular morphology and flow was implemented. A detailed analysis of X-ray fluoroscopic angiography workflow was conducted and applied. Two interventional radiologists and one physician in training performed 39 procedures. All procedures were timed and analyzed. RESULTS MRI-guided iliac angioplasty procedures were successfully performed with progressive adaptation of techniques and workflow. The workflow, setup and protocol enabled a reduction in table time for a dedicated MRI-guided procedure to 6 min 33 s with a mean procedure time of 9 min 2 s, comparable to the mean procedure time of 8 min 42 s for the standard X-ray-guided procedure. CONCLUSIONS MRI-guided iliac vascular interventions were found to be feasible and practical using this framework and optimized workflow. In particular, the real-time flow analysis was found to be helpful for pre- and post-interventional assessments. Design optimization of the catheters and in vivo experiments are required before clinical evaluation.
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Affiliation(s)
- Martin A Rube
- Division of Imaging and Technology, Institute for Medical Science and Technology, University of Dundee, Wilson House, 1 Wurzburg Loan, Dundee, DD2 1FD, UK,
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Hartkamp NS, Petersen ET, De Vis JB, Bokkers RPH, Hendrikse J. Mapping of cerebral perfusion territories using territorial arterial spin labeling: techniques and clinical application. NMR IN BIOMEDICINE 2013; 26:901-912. [PMID: 22807022 DOI: 10.1002/nbm.2836] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 06/12/2012] [Accepted: 06/17/2012] [Indexed: 06/01/2023]
Abstract
A knowledge of the exact cerebral perfusion territory which is supplied by any artery is of great importance in the understanding and diagnosis of cerebrovascular disease. The development and optimization of territorial arterial spin labeling (T-ASL) MRI techniques in the past two decades have made it possible to visualize and determine the cerebral perfusion territories in individual patients and, more importantly, to do so without contrast agents or otherwise invasive procedures. This review provides an overview of the development of ASL techniques that aim to visualize the general cerebral perfusion territories or the territory of a specific artery of interest. The first efforts of T-ASL with pulsed, continuous and pseudo-continuous techniques are summarized and subsequent clinical studies using T-ASL are highlighted. In the healthy population, the perfusion territories of the brain-feeding arteries are highly variable. This high variability requires special consideration in specific patient groups, such as patients with cerebrovascular disease, stroke, steno-occlusive disease of the large arteries and arteriovenous malformations. In the past, catheter angiography with selective contrast injection was the only available method to visualize the cerebral perfusion territories in vivo. Several T-ASL methods, sometimes referred to as regional perfusion imaging, are now available that can easily be combined with conventional brain MRI examinations to show the relationship between the cerebral perfusion territories, vascular anatomy and brain infarcts or other pathology. Increased availability of T-ASL techniques on clinical MRI scanners will allow radiologists and other clinicians to gain further knowledge of the relationship between vasculature and patient diagnosis and prognosis. Treatment decisions, such as surgical revascularization, may, in the near future, be guided by information provided by T-ASL MRI in close correlation with structural MRI and quantitative perfusion information.
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Affiliation(s)
- Nolan S Hartkamp
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
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Brunner A, Maier F, Krafft AJ, Semmler W, Bock M. Two eyes see more than one: double echo stereoscopic MRA for rapid 3D visualization of vascular structures. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2012; 25:411-8. [PMID: 22476546 DOI: 10.1007/s10334-012-0313-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 02/09/2012] [Accepted: 03/01/2012] [Indexed: 11/28/2022]
Abstract
OBJECT A three-dimensional (3D) visualization of the target region during intravascular interventions in real-time is challenging since the acquisition of a time-consuming 3D dataset is required. In this work, a novel stereoscopic double echo sequence for achieving 3D depth perception by sampling only two oblique projection images is presented. MATERIALS AND METHODS A double echo (DE) FLASH pulse sequence was developed to acquire continuously stereoscopic image pairs of the vascular target anatomy. Stereo image data were displayed on a stereoscopic 3D LCD monitor in real time after image reconstruction. Phantom experiments followed by a depth perception test were performed to assess the usability of the stereo image pairs for 3D visualization. In an animal experiment the sequence was tested in vivo and was compared with a slower interleaved (IL) sequence variant. RESULTS In the phantom experiments an SNR difference of 6 % between left and right image was found which did not influence the depth perception. The DE acquisition was superior to the IL sequence (SNR(DE) = 10.3, 2.3 images/s over SNR(IL) = 7.1, 1.7 images/s), and during contrast enhancement the abdominal arterial vasculature was clearly perceived as a 3D structure. CONCLUSION A novel stereoscopic DE pulse sequence can be utilized for the fast 3D stereoscopic visualization of vascular structures in real-time.
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Affiliation(s)
- Alexander Brunner
- Department of Medical Physics in Radiology, German Cancer Research Center, DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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Shih MCP, Rogers WJ, Bonatti H, Hagspiel KD. Real-time MR-guided retrieval of inferior vena cava filters: an in vitro and animal model study. J Vasc Interv Radiol 2011; 22:843-50. [PMID: 21482139 DOI: 10.1016/j.jvir.2011.01.428] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 12/16/2010] [Accepted: 01/02/2011] [Indexed: 11/15/2022] Open
Abstract
PURPOSE To develop interventional magnetic resonance (MR) guidance techniques for inferior vena cava (IVC) filter retrieval in vitro and demonstrate feasibility in vivo. MATERIALS AND METHODS Three optional IVC filters and their retrieval systems were investigated. Experiments were performed on a 1.5-T MR system. Real-time MR imaging was optimized by using a custom-built IVC phantom. A three-dimensional (3D) contrast-enhanced MR venography sequence was optimized in vitro for improved detection of thrombus trapped within the filters. Filters were then retrieved in vitro and in vivo in a swine model under MR guidance. In-vivo retrieval procedure time was measured. RESULTS The combination of one of the nitinol filters and a loop snare was suitable for real-time MR procedures. With a 90° flip angle, 3D MR venography allowed detection of simulated thrombus within the filter. A radial true fast imaging sequence with steady-state precession allowed visualization of the loop snare and IVC filter hook and successful retrieval of the filter in vivo and in vitro. In-vivo MR fluoroscopy time for retrieval was 97 seconds ± 51 (mean ± SD). CONCLUSIONS MR-guided retrieval of a nitinol-based IVC filter by using a loop snare is feasible with the use of optimized sequences and passive device tracking.
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Affiliation(s)
- Ming-Chen Paul Shih
- Department of Radiology and Medical Imaging, University of Virginia Health System, Lee Street, Charlottesville, VA 22908, USA
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Ley S, Zaporozhan J, Arnold R, Eichhorn J, Schenk JP, Ulmer H, Kreitner KF, Kauczor HU. Preoperative assessment and follow-up of congenital abnormalities of the pulmonary arteries using CT and MRI. Eur Radiol 2006; 17:151-62. [PMID: 16799783 DOI: 10.1007/s00330-006-0300-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 04/09/2006] [Accepted: 04/18/2006] [Indexed: 12/01/2022]
Abstract
Congenital heart disease (CHD), including complex anomalies of the pulmonary arteries, are now earlier diagnosed and treated. Due to improvements in interventional and surgical therapy, the number of patients with the need for follow-up examinations is increasing. Pre- and postinterventional imaging should be done as gently as possible, avoiding invasive techniques if possible. With the technical improvement of multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI), both techniques are increasingly used for noninvasive assessment of the pulmonary vasculature in children with CHD. Knowledge of the most common diseases affecting the pulmonary vasculature and the kind of surgical and interventional procedures is essential for optimal imaging planning. This is especially important because interventions can be positively influenced by high-quality imaging. Therefore, the most common diseases and procedures are described and imaging modality of choice and important image findings are discussed.
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Affiliation(s)
- Sebastian Ley
- Department of Pediatric Radiology, University Children's Hospital, Im Neuenheimer Feld 153, 69120 Heidelberg, Germany.
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