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Schröer S, Düx D, Löning Caballero JJ, Glandorf J, Gerlach T, Horstmann D, Belker O, Gutt M, Wacker F, Speck O, Hensen B, Gutberlet M. Reducing electromagnetic interference in MR thermometry: A comparison of setup configurations for MR-guided microwave ablations. Z Med Phys 2024:S0939-3889(24)00055-2. [PMID: 39129075 DOI: 10.1016/j.zemedi.2024.07.004] [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: 10/28/2023] [Revised: 05/17/2024] [Accepted: 07/11/2024] [Indexed: 08/13/2024]
Abstract
Magnetic Resonance (MR) thermometry is used for the monitoring of MR-guided microwave ablations (MWA), and for the intraoperative evaluation of ablation regions. Nevertheless, the accuracy of temperature mapping may be compromised by electromagnetic interference emanating from the microwave (MW) generator. This study evaluated different setups for improving magnetic resonance imaging (MRI) during MWA with a modified MW generator. MWA was performed in 15 gel phantoms comparing three setups: The MW generator was placed outside the MR scanner room, either connected to the MW applicator using a penetration panel with a radiofrequency (RF) filter and a 7 m coaxial cable (Setup 1), or through a waveguide using a 5 m coaxial cable (Setup 2). Setup 3 employed the MW generator within the MR scan room, connected by a 5 m coaxial cable. The coaxial cables in setups 2 and 3 were modified with custom shielding to reduce interference. The setups during ablation (active setup) were compared to a reference setup without the presence of the MW system. Thermometry and thermal dose maps (CEM43 model) were compared for the three configurations. Primary endpoints for assessment were signal-to-noise ratio (SNR), temperature precision, Sørensen-Dice-Coefficient (DSC), and RF-noise spectra. Setup 3 showed highly significant electromagnetic interference during ablation with a SNR decrease by -60.4%±13.5% (p<0.001) compared to reference imaging. For setup 1 and setup 2 no significant decrease in SNR was measured with differences of -2.9%±9.8% (p=0.6) and -1.5%±12.8% (p=0.8), respectively. SNR differences were significant between active setups 1 and 3 with -51.2%±16.1% (p<0.001) and between active setups 2 and 3 with -59.0%±15.5% (p<0.001) but not significant between active setups 1 and 2 with 19.0%±13.7% (p=0.09). Furthermore, no significant differences were seen in temperature precision or DSCs between all setups, ranging from 0.33 °C ± 0.04 °C (Setup 1) to 0.38 °C ± 0.06 °C (Setup 3) (p=0.6) and from 87.0%±1.6% (Setup 3) to 88.1%±1.6% (Setup 2) (p=0.58), respectively. Both setups (1 and 2) with the MW generator outside the MR scanner room were beneficial to reduce electromagnetic interference during MWA. Moreover, provided that a shielded cable is utilized in setups 2 and 3, all configurations displayed negligible differences in temperature precision and DSCs, indicating that the location of the MW generator does not significantly impact the accuracy of thermometry during MWA.
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Affiliation(s)
- Simon Schröer
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany.
| | - Daniel Düx
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Josef Joaquin Löning Caballero
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Julian Glandorf
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Thomas Gerlach
- Otto-von-Guericke-Universität, Universitätsplatz 2, Magdeburg 39106, Saxony-Anhalt, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Dominik Horstmann
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Othmar Belker
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Moritz Gutt
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Frank Wacker
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Oliver Speck
- Otto-von-Guericke-Universität, Universitätsplatz 2, Magdeburg 39106, Saxony-Anhalt, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Bennet Hensen
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
| | - Marcel Gutberlet
- Hannover Medical School, Carl-Neuberg-Straße 1, Hanover 30625, Lower Saxony, Germany; Research Campus STIMULATE, Otto-Hahn-Straße 2, Magdeburg 39106, Saxony-Anhalt, Germany
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Schröer S, Alpers J, Gutberlet M, Brüsch I, Rumpel R, Wacker F, Hensen B, Hansen C. A probabilistic thermal dose model for the estimation of necrosis in MR-guided tumor ablations. Med Phys 2024; 51:239-250. [PMID: 37449443 DOI: 10.1002/mp.16605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 04/25/2023] [Accepted: 06/20/2023] [Indexed: 07/18/2023] Open
Abstract
BACKGROUND Monitoring minimally invasive thermo ablation procedures using magnetic resonance (MR) thermometry allows therapy of tumors even close to critical anatomical structures. Unfortunately, intraoperative monitoring remains challenging due to the necessary accuracy and real-time capability. One reason for this is the statistical error introduced by MR measurement, which causes the prediction of ablation zones to become inaccurate. PURPOSE In this work, we derive a probabilistic model for the prediction of ablation zones during thermal ablation procedures based on the thermal damage model CEM43 . By integrating the statistical error caused by MR measurement into the conventional prediction, we hope to reduce the amount of falsely classified voxels. METHODS The probabilistic CEM43 model is empirically evaluated using a polyacrilamide gel phantom and three in-vivo pig livers. RESULTS The results show a higher accuracy in three out of four data sets, with a relative difference in Sørensen-Dice coefficient from- 3.04 % $-3.04\%$ to 3.97% compared to the conventional model. Furthermore, the ablation zones predicted by the probabilistic model show a false positive rate with a relative decrease of 11.89%-30.04% compared to the conventional model. CONCLUSION The presented probabilistic thermal dose model might help to prevent false classification of voxels within ablation zones. This could potentially result in an increased success rate for MR-guided thermal ablation procedures. Future work may address additional error sources and a follow-up study in a more realistic clinical context.
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Affiliation(s)
- Simon Schröer
- Department of Diagnostic and Interventional Radiology, Medical School Hanover, Hanover, Germany
- Department of Simulation and Graphics, Otto-von-Guericke-University, Magdeburg, Germany
| | - Julian Alpers
- Department of Simulation and Graphics, Otto-von-Guericke-University, Magdeburg, Germany
| | - Marcel Gutberlet
- Department of Diagnostic and Interventional Radiology, Medical School Hanover, Hanover, Germany
| | - Inga Brüsch
- Department of Laboratory Animal Science, Medical School Hanover, Hanover, Germany
| | - Regina Rumpel
- Department of Laboratory Animal Science, Medical School Hanover, Hanover, Germany
| | - Frank Wacker
- Department of Diagnostic and Interventional Radiology, Medical School Hanover, Hanover, Germany
| | - Bennet Hensen
- Department of Diagnostic and Interventional Radiology, Medical School Hanover, Hanover, Germany
| | - Christian Hansen
- Department of Simulation and Graphics, Otto-von-Guericke-University, Magdeburg, Germany
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Ozenne V, Bour P, Denis de Senneville B, Quesson B. 3D motion strategy for online volumetric thermometry using simultaneous multi-slice EPI at 1.5T: an evaluation study. Int J Hyperthermia 2023; 40:2194595. [PMID: 37080550 DOI: 10.1080/02656736.2023.2194595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023] Open
Abstract
PURPOSE In presence of respiratory motion, temperature mapping is altered by in-plane and through-plane displacements between successive acquisitions together with periodic phase variations. Fast 2D Echo Planar Imaging (EPI) sequence can accommodate intra-scan motion, but limited volume coverage and inter-scan motion remain a challenge during free-breathing acquisition since position offsets can arise between the different slices. METHOD To address this limitation, we evaluated a 2D simultaneous multi-slice EPI sequence with multiband (MB) acceleration during radiofrequency ablation on a mobile gel and in the liver of a volunteer (no heating). The sequence was evaluated in terms of resulting inter-scan motion, temperature uncertainty and elevation, potential false-positive heating and repeatability. Lastly, to account for potential through-plane motion, a 3D motion compensation pipeline was implemented and evaluated. RESULTS In-plane motion was compensated whatever the MB factor and temperature distribution was found in agreement during both the heating and cooling periods. No obvious false-positive temperature was observed under the conditions being investigated. Repeatability of measurements results in a 95% uncertainty below 2 °C for MB1 and MB2. Uncertainty up to 4.5 °C was reported with MB3 together with the presence of aliasing artifacts. Lastly, fast simultaneous multi-slice EPI combined with 3D motion compensation reduce residual out-of-plane motion. CONCLUSION Volumetric temperature imaging (12 slices/700 ms) could be performed with 2 °C accuracy or less, and offer tradeoffs in acquisition time or volume coverage. Such a strategy is expected to increase procedure safety by monitoring large volumes more rapidly for MR-guided thermotherapy on mobile organs.
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Affiliation(s)
- Valéry Ozenne
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac-Bordeaux, France
- University of Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, Bordeaux, France
- INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, Bordeaux, France
| | - Pierre Bour
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac-Bordeaux, France
- University of Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, Bordeaux, France
- INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, Bordeaux, France
| | | | - Bruno Quesson
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac-Bordeaux, France
- University of Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, Bordeaux, France
- INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, Bordeaux, France
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Dual-Applicator MR Imaging-Guided Microwave Ablation with Real-Time MR Thermometry: Phantom and Porcine Tissue Model Experiments. J Vasc Interv Radiol 2023; 34:46-53.e4. [PMID: 36202337 DOI: 10.1016/j.jvir.2022.09.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 08/17/2022] [Accepted: 09/29/2022] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To investigate the effect of simultaneous use of dual applicators on the image quality of real-time magnetic resonance (MR) thermometry and to characterize the dual-applicator treatment zone pattern during MR imaging-guided microwave ablation (MWA). MATERIALS AND METHODS MWA experiments were performed on a 1.5-T MR scanner with 2 commercial microwave systems (902-928 MHz). Phantom experiments were first performed to evaluate the effect of dual-applicator MWA on the image quality of MR. Then, porcine tissue model experiments were conducted with real-time MR thermometry using either a single applicator or dual applicators inserted 2.6, 3.6, and 4.6 cm apart. Fiberoptic thermal probes were used to measure the temperature changes at the tissue surface. RESULTS Simultaneous use of dual applicators resulted in a decrease in the relative signal-to-noise ratio (SNR) in the MR thermometry images to 55% ± 2.9% when compared with that of a single applicator (86.2% ± 2.0%). Despite the lower SNR, the temperature and ablation zone maps were of adequate quality to allow visualization of the ablation zone(s). The extents of increase in the temperature at the tissue surface using dual applicators (19.7 °C ± 2.6 °C) and a single applicator (18.2 °C ± 3.3 °C) were not significantly different (P = .40). Treatment zones were significantly larger (P < .05) in dual-applicator ablations (29.4 ± 0.4, 39.9 ± 0.6, and 42.6 ± 0.9 cm2 with 2.6-, 3.6-, and 4.6-cm spacing, respectively) at the end of the ablation procedure than in the single-applicator MWA (18.6 ± 0.9 cm2). CONCLUSIONS MR imaging-guided dual-applicator MWA produced larger ablation zones while allowing adequate real-time MR thermometry image quality for monitoring the evolution of the treatment zone.
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Abrishami Kashani M, Campbell-Washburn AE, Murphy MC, Catalano OA, McDermott S, Fintelmann FJ. Magnetic Resonance Imaging for Guidance and Follow-up of Thoracic Needle Biopsies and Thermal Ablations. J Thorac Imaging 2022; 37:201-216. [PMID: 35426857 PMCID: PMC10441002 DOI: 10.1097/rti.0000000000000651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Magnetic resonance imaging (MRI) is used for the guidance and follow-up of percutaneous minimally invasive interventions in many body parts. In the thorax, computed tomography (CT) is currently the most used imaging modality for the guidance and follow-up of needle biopsies and thermal ablations. Compared with CT, MRI provides excellent soft tissue contrast, lacks ionizing radiation, and allows functional imaging. The role of MRI is limited in the thorax due to the low hydrogen proton density and many air-tissue interfaces of the lung, as well as respiratory and cardiac motion. Here, we review the current experience of MR-guided thoracic needle biopsies and of MR-guided thermal ablations targeting lesions in the lung, mediastinum, and the chest wall. We provide an overview of MR-compatible biopsy needles and ablation devices. We detail relevant MRI sequences and their relative advantages and disadvantages for procedural guidance, assessment of complications, and long-term follow-up. We compare the advantages and disadvantages of CT and MR for thoracic interventions and identify areas in need of improvement and additional research.
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Affiliation(s)
| | - Adrienne E Campbell-Washburn
- Division of Intramural Research, Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Mark C Murphy
- Division of Thoracic Imaging and Intervention, Department of Radiology
| | - Onofrio A Catalano
- Division of Abdominal Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA
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Hubmann J, Gerlach T, Pannicke E, Hensen B, Wacker F, Speck O, Vick R. Design of a System for Magnetic-Resonance-Guided Irreversible Electroporation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:1457-1461. [PMID: 34891560 DOI: 10.1109/embc46164.2021.9630723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Irreversible electroporation (IRE) is a non-thermal tumor ablation method where strong electrical fields between at least two electrodes are used and can be seen as an alternative to thermal ablation techniques. The therapy outcome directly dependents on the position of the electrodes. Real-time monitoring of the IRE by magnetic resonance imaging (MRI) would allow to detect unwanted electrode displacement and to apply visualization methods for the ablation area. This requires that the IRE generator does not significantly interfere with the MRI. Currently, there is no IRE generator available designed for MRI-guided IRE.This paper presents an IRE system specifically developed for use in an MRI environment. The system is initially tested with a standard IRE sequence and then the interference between a clinical 3 T MRI device and the IRE system is investigated using a noise measurement and the signal-to-noise ratio (SNR) of images acquired with a gradient echo (GRE) sequence. The results show, that although the SNR of the images decrease by maximal 36 % when the IRE system is switched on, image quality does not visibly degrade. Hence, MRI-guided IRE is feasible with the proposed system.Clinical relevance- This paper demonstrates the possibility of MRI-guided IRE with only minor image degradation when the IRE system is used in parallel with MRI imaging.
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