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Faust JF, Krafft AJ, Polak D, Speier P, Behl NGR, Ooms N, Roll J, Krieger J, Ladd ME, Maier F. Rapid CNN-based needle localization for automatic slice alignment in MR-guided interventions using 3D undersampled radial white-marker imaging. Med Phys 2024. [PMID: 39292615 DOI: 10.1002/mp.17376] [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: 02/09/2024] [Revised: 06/25/2024] [Accepted: 07/31/2024] [Indexed: 09/20/2024] Open
Abstract
BACKGROUND In MR-guided in-bore percutaneous needle interventions, typically 2D interactive real-time imaging is used for navigating the needle into the target. Misaligned 2D imaging planes can result in losing visibility of the needle in the 2D images, which impedes successful targeting. Necessary iterative manual slice adjustment can prolong interventional workflows. Therefore, rapid automatic alignment of the imaging planes with the needle would be preferable to improve such workflows. PURPOSE To investigate rapid 3D localization of needles in MR-guided interventions via a convolutional neural network (CNN)-based localization algorithm using an undersampled white-marker contrast acquisition for the purpose of automatic imaging slice alignment. METHODS A radial 3D rf-spoiled gradient echo MR pulse sequence with white-marker encoding was implemented and a CNN-based localization algorithm was employed to extract position and orientation of an aspiration needle from the undersampled white-marker images. The CNN was trained using porcine tissue phantoms (257 needle trajectories, four-fold data augmentation, 90%/10% split into training and validation dataset). Achievable localization times and accuracy were evaluated retrospectively in an ex vivo study (109 needle trajectories) for a range of needle orientations between 78° and 90° relative to the B0 field. A proof-of-concept in vivo experiment was performed in two porcine animal models and feasibility of automatic imaging slice alignment was evaluated retrospectively. RESULTS Ex vivo needle localization was achieved with a median localization accuracy of 1.9 mm (distance needle tip to detected needle axis) and a median angular deviation of 2.6° for needle orientations between 86° and 90° to the B0 field from fully sampled WM images (resolution of (4 mm)3, 6434 acquired radial k-space spokes, acquisition time of 80.4 s) in a field-of-view of (256 mm)3. Localization accuracy decreased with increasing undersampling and needle trajectory increasingly aligned with B0. For needle orientations between 86° and 90° to the B0 field, a highly accelerated acquisition of only 32 k-space spokes (acquisition time of 0.4 s) yielded a median localization accuracy of 3.1 mm and a median angular deviation of 4.7°. For needle orientations between 78° and 82° to the B0 field, a median accuracy and angular deviation of 3.5 mm and 6.8° could still be achieved with 64 sampled spokes (acquisition time of 0.8 s). In vivo, a localization accuracy of 1.4 mm and angular deviation of 3.4° was achieved sampling 32 k-space spokes (acquisition time of 0.48 s) with the needle oriented at 87.7° to the B0 field. For a needle oriented at 77.6° to the B0 field, localization accuracy of 5.3 mm and angular deviation of 6.8° were still achieved sampling 128 k-space spokes (acquisition time of 1.92 s), allowing for retrospective slice alignment. CONCLUSION The investigated approach enables passive biopsy needle localization in 3D. Acceleration of the localization to real-time applicability is feasible for needle orientations approximately perpendicular to B0. The method can potentially facilitate MR-guided needle interventions by enabling automatic imaging slice alignment with the needle.
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Affiliation(s)
- Jonas Frederik Faust
- Faculty of Physics and Astronomy, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
- Siemens Healthineers AG, Erlangen, Germany
| | | | | | | | | | - Nathan Ooms
- Cook Advanced Technologies, West Lafayette, Indiana, USA
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Jesse Roll
- Cook Advanced Technologies, West Lafayette, Indiana, USA
| | - Joshua Krieger
- Cook Advanced Technologies, West Lafayette, Indiana, USA
| | - Mark Edward Ladd
- Faculty of Physics and Astronomy, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Medicine, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
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Spronk T, Kraff O, Schaefers G, Quick HH. Numerical approach to investigate MR imaging artifacts from orthopedic implants at different field strengths according to ASTM F2119. MAGMA (NEW YORK, N.Y.) 2023; 36:725-735. [PMID: 36933090 PMCID: PMC10504103 DOI: 10.1007/s10334-023-01074-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 02/24/2023] [Accepted: 02/26/2023] [Indexed: 03/19/2023]
Abstract
OBJECTIVE This study presents an extended evaluation of a numerical approach to simulate artifacts of metallic implants in an MR environment. METHODS The numerical approach is validated by comparing the artifact shape of the simulations and measurements of two metallic orthopedic implants at three different field strengths (1.5 T, 3 T, and 7 T). Furthermore, this study presents three additional use cases of the numerical simulation. The first one shows how numerical simulations can improve the artifact size evaluation according to ASTM F2119. The second use case quantifies the influence of different imaging parameters (TE and bandwidth) on the artifact size. Finally, the third use case shows the potential of performing human model artifact simulations. RESULTS The numerical simulation approach shows a dice similarity coefficient of 0.74 between simulated and measured artifact sizes of metallic implants. The alternative artifact size calculation method presented in this study shows that the artifact size of the ASTM-based method is up to 50% smaller for complex shaped implants compared to the numerical-based approach. CONCLUSION In conclusion, the numerical approach could be used in the future to extend MR safety testing according to a revision of the ASTM F2119 standard and for design optimization during the development process of implants.
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Affiliation(s)
- Tobias Spronk
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Kokereiallee 7, Building C84, 45141, Essen, Germany.
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
- MRI-STaR Magnetic Resonance Institute for Safety GmbH, Technology and Research GmbH, Gelsenkirchen, Germany.
| | - Oliver Kraff
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Kokereiallee 7, Building C84, 45141, Essen, Germany
| | - Gregor Schaefers
- MRI-STaR Magnetic Resonance Institute for Safety GmbH, Technology and Research GmbH, Gelsenkirchen, Germany
- MR:Comp GmbH, Testing Services for MR Safety and Compatibility, Gelsenkirchen, Germany
| | - Harald H Quick
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Kokereiallee 7, Building C84, 45141, Essen, Germany
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, Germany
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Haskell MW, Nielsen JF, Noll DC. Off-resonance artifact correction for MRI: A review. NMR IN BIOMEDICINE 2023; 36:e4867. [PMID: 36326709 PMCID: PMC10284460 DOI: 10.1002/nbm.4867] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 09/25/2022] [Accepted: 11/01/2022] [Indexed: 06/06/2023]
Abstract
In magnetic resonance imaging (MRI), inhomogeneity in the main magnetic field used for imaging, referred to as off-resonance, can lead to image artifacts ranging from mild to severe depending on the application. Off-resonance artifacts, such as signal loss, geometric distortions, and blurring, can compromise the clinical and scientific utility of MR images. In this review, we describe sources of off-resonance in MRI, how off-resonance affects images, and strategies to prevent and correct for off-resonance. Given recent advances and the great potential of low-field and/or portable MRI, we also highlight the advantages and challenges of imaging at low field with respect to off-resonance.
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Affiliation(s)
- Melissa W Haskell
- Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, USA
- Hyperfine Research, Guilford, Connecticut, USA
| | | | - Douglas C Noll
- Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
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Kaza E, Lee CY, King MT, Dyer MA, Cormack RA, Buzurovic I. First pointwise encoding time reduction with radial acquisition (PETRA) implementation for catheter detection in interstitial high-dose-rate (HDR) brachytherapy. Brachytherapy 2022; 21:501-510. [PMID: 35337748 DOI: 10.1016/j.brachy.2022.01.003] [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: 09/25/2021] [Revised: 12/15/2021] [Accepted: 01/15/2022] [Indexed: 11/02/2022]
Abstract
PURPOSE A pointwise encoding time reduction with radial acquisition (PETRA) sequence was optimized to detect empty catheters in interstitial (HDR) brachytherapy with clinically acceptable spatial accuracy for the first time. Image quality and catheter detectability were assessed in phantoms, and the feasibility of PETRA's clinical implementation was assessed on a gynecological cancer patient. METHODS AND RESULTS Empty catheters embedded in a gelatin phantom displayed positive signal on PETRA and more accurate cross-sections than on clinically employed T2-weighted sequences, differing by 0.4 mm on average from their nominal 2 mm diameter. PETRA presented minimal susceptibility differences and a symmetric metal artifact, contrary to the clinical sequences. The PETRA-CT catheter tip position differences assessed by a treatment planning system (TPS) were < 1 mm. PETRA also detected an interstitial template with empty catheters penetrating a poultry phantom and fused very well with CT. Interstitial catheter positional difference between PETRA and CT images was < 1 mm on average, increasing with distance from isocenter. All interstitial catheters and the employed interstitial template were detected on PETRA images of an endometrial adenocarcinoma patient. Empty needles were traceable using a TPS, with higher spatial resolution and more favorable contrast than on T2-weighted images used for contouring. A treatment plan could be produced by combining information from PETRA for catheter detection and from T2-weighted images for tumor and organs delineation. CONCLUSIONS PETRA detected successfully and accurately interstitial catheters in phantoms. Its first clinical implementation shows a potential for MR-only treatment planning in interstitial HDR brachytherapy.
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Affiliation(s)
- Evangelia Kaza
- Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA.
| | - Casey Y Lee
- Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
| | - Martin T King
- Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
| | - Michael A Dyer
- Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
| | - Robert A Cormack
- Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
| | - Ivan Buzurovic
- Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
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He C, Zhang F, Li L, Jiang C, Li L. Measurement of Lead Localization Accuracy Based on Magnetic Resonance Imaging. Front Neurosci 2021; 15:632822. [PMID: 35002596 PMCID: PMC8727439 DOI: 10.3389/fnins.2021.632822] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 11/04/2021] [Indexed: 11/13/2022] Open
Abstract
Post-implantation localization of deep brain stimulation (DBS) lead based on a magnetic resonance (MR) image is widely used. Existing localization methods use artifact center method or template registration method, which may lead to a considerable deviation of > 2 mm, and result in severe side effects or even surgical failure. Accurate measurement of lead position can instantly inform surgeons of the imprecise implantation. This study aimed to identify the influencing factors in DBS lead post-implantation localization approach, analyze their influence, and describe a localization approach that uses the individual template method to reduce the deviation. We verified that reconstructing direction should be parallel or perpendicular to lead direction, instead of the magnetic field. Besides, we used simplified relationship between magnetic field angle and deviation error to correct the localization results. The mean localization error can be reduced after correction and favors the feasibility of direct localization of DBS lead using MR images. We also discussed influence of in vivo noise on localization frequency and the possibility of using only MR images to localize the contacts.
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Affiliation(s)
- Changgeng He
- National Engineering Laboratory for Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Feng Zhang
- National Engineering Laboratory for Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Linze Li
- National Engineering Laboratory for Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Changqing Jiang
- National Engineering Laboratory for Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Luming Li
- National Engineering Laboratory for Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing, China
- Precision Medicine and Healthcare Research Center, Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
- Institute of Epilepsy, Beijing Institute for Brain Disorders, Beijing, China
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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: 2] [Impact Index Per Article: 0.7] [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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Peschke E, Ulloa P, Jansen O, Hoevener JB. Metallic Implants in MRI - Hazards and Imaging Artifacts. ROFO-FORTSCHR RONTG 2021; 193:1285-1293. [PMID: 33979870 DOI: 10.1055/a-1460-8566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND Magnetic resonance imaging (MRI) is an examination method for noninvasive soft tissue imaging without the use of ionizing radiation. Metallic implants, however, may pose a risk for the patient and often result in imaging artifacts. Due to the increasing number of implants, reducing these artifacts has become an important goal. In this review, we describe the risks associated with implants and provide the background on how metal-induced artifacts are formed. We review the literature on methods on how to reduce artifacts and summarize our findings. METHOD The literature was searched using PubMed and the keywords "MRI metal artifact reduction", "metallic implants" and "MRI artefacts/artifacts". RESULTS AND CONCLUSION The MRI compatibility of implants has to be evaluated individually. To reduce artifacts, two general approaches were found: a) parameter optimization in standard sequences (echo time, slice thickness, bandwidth) and b) specialized sequences, such as VAT, OMAR, WARP, SEMAC and MAVRIC. These methods reduced artifacts and improved image quality, albeit at the cost of a (sometimes significantly) prolonged scan time. New developments in accelerated imaging will likely shorten the scan time of these methods significantly, such that routine use may become feasible. KEY POINTS · Metallic implants may pose a risk for patients and often cause artifacts.. · Imaging artifacts can be reduced by parameter optimization or special sequences.. · Metal artifacts are reduced with a lower TE, smaller voxel size, larger matrix, and higher bandwidth.. · SPI, STIR, VAT, SEMAC, MAVRIC, and MAVRIC-SL are specialized MR sequences that can reduce artifacts further.. CITATION FORMAT · Peschke E, Ulloa P, Jansen O et al. Metallic Implants in MRI - Hazards and Imaging Artifacts. Fortschr Röntgenstr 2021; 193: 1285 - 1293.
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Affiliation(s)
- Eva Peschke
- Department for Radiology and Neuroradiology, Molecular Imaging North Competence Center (MOIN CC), Section Biomedical Imaging, University Hospital Schleswig-Holstein - Campus Kiel, Kiel University, Germany
| | - Patricia Ulloa
- Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein - Campus Kiel, Germany
| | - Olav Jansen
- Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein - Campus Kiel, Germany
| | - Jan-Bernd Hoevener
- Department for Radiology and Neuroradiology, Molecular Imaging North Competence Center (MOIN CC), Section Biomedical Imaging, University Hospital Schleswig-Holstein - Campus Kiel, Kiel University, Germany
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Okamoto S, Matsui Y, Hiraki T, Iguchi T, Komaki T, Yamauchi T, Uka M, Tomita K, Sakurai J, Gobara H, Kanazawa S. Needle artifact characteristics and insertion accuracy using a 1.2T open MRI scanner: A phantom study. Diagn Interv Imaging 2021; 102:363-370. [PMID: 33518449 DOI: 10.1016/j.diii.2020.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/23/2020] [Accepted: 12/28/2020] [Indexed: 01/20/2023]
Abstract
PURPOSE To evaluate the characteristics of needle artifacts and the accuracy of needle insertion using a 1.2 Tesla open magnetic resonance imaging (MRI) system in a phantom. MATERIALS AND METHODS First, the apparent width of the needle on the MRI and the needle tip position error of 16- and 18-gauge MRI-compatible introducer needles and a 17-gauge cryoneedle were examined with different needle angles (0°, 30°, 45°, 60°, and 90°) to the main magnetic field (B0), sequence types (balanced steady-state acquisition with rewound gradient echo [BASG] and T2-weighted fast spin echo [FSE] sequence), and frequency encoding directions. Second, the accuracy of needle insertion was evaluated after 10 MRI fluoroscopy-guided insertions in a phantom. RESULTS The apparent needle widths was larger when the angle of the needle axis relative to B0 was larger. The needles appeared larger on BASG than on T2-weighted FSE images, with the largest apparent widths of 16-, 17-, and 18-gauge needles of 14.3, 11.6, and 11.0mm, respectively. The apparent needle tip position was always more distal than the actual position on BASG images, with the largest longitudinal error of 4.0mm. Meanwhile, the 16- and 18-gauge needle tips appeared more proximal on T2-weighted FSE images with right-to-left frequency encoding direction. The mean accuracy of MRI fluoroscopy-guided needle insertion was 3.1mm. CONCLUSION These experiments clarify the characteristics of needle artifacts in a 1.2 Tesla open MRI. With this system, the MRI fluoroscopy-guided needle insertion demonstrated an acceptable accuracy for clinical use.
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Affiliation(s)
- Soichiro Okamoto
- Department of Radiology, Okayama University Medical School, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan
| | - Yusuke Matsui
- Department of Radiology, Okayama University Medical School, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan.
| | - Takao Hiraki
- Department of Radiology, Okayama University Medical School, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan
| | - Toshihiro Iguchi
- Department of Radiology, Okayama University Medical School, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan
| | - Toshiyuki Komaki
- Department of Radiology, Okayama University Medical School, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan
| | - Takatsugu Yamauchi
- Central Division of Radiology, Okayama University Hospital, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan
| | - Mayu Uka
- Department of Radiology, Okayama University Medical School, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan
| | - Koji Tomita
- Department of Radiology, Okayama University Medical School, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan
| | - Jun Sakurai
- Center for Innovative Clinical Medicine, Okayama University Hospital, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan
| | - Hideo Gobara
- Division of Medical Informatics, Okayama University Hospital, 2-5-1 Shikatacho, Kitaku, 700-8558, Okayama, Japan
| | - Susumu Kanazawa
- Department of Radiology, Okayama University Medical School, 2-5-1 Shikatacho, Kitaku, Okayama 700-8558, Japan
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Li X, Young AS, Raman SS, Lu DS, Lee YH, Tsao TC, Wu HH. Automatic needle tracking using Mask R-CNN for MRI-guided percutaneous interventions. Int J Comput Assist Radiol Surg 2020; 15:1673-1684. [PMID: 32676870 DOI: 10.1007/s11548-020-02226-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 07/03/2020] [Indexed: 12/16/2022]
Abstract
PURPOSE Accurate needle tracking provides essential information for MRI-guided percutaneous interventions. Passive needle tracking using MR images is challenged by variations of the needle-induced signal void feature in different situations. This work aimed to develop an automatic needle tracking algorithm for MRI-guided interventions based on the Mask Region Proposal-Based Convolutional Neural Network (R-CNN). METHODS Mask R-CNN was adapted and trained to segment the needle feature using 250 intra-procedural images from 85 MRI-guided prostate biopsy cases and 180 real-time images from MRI-guided needle insertion in ex vivo tissue. The segmentation masks were passed into the needle feature localization algorithm to extract the needle feature tip location and axis orientation. The proposed algorithm was tested using 208 intra-procedural images from 40 MRI-guided prostate biopsy cases, and 3 real-time MRI datasets in ex vivo tissue. The algorithm results were compared with human-annotated references. RESULTS In prostate datasets, the proposed algorithm achieved needle feature tip localization error with median Euclidean distance (dxy) of 0.71 mm and median difference in axis orientation angle (dθ) of 1.28°, respectively. In 3 real-time MRI datasets, the proposed algorithm achieved consistent dynamic needle feature tracking performance with processing time of 75 ms/image: (a) median dxy = 0.90 mm, median dθ = 1.53°; (b) median dxy = 1.31 mm, median dθ = 1.9°; (c) median dxy = 1.09 mm, median dθ = 0.91°. CONCLUSIONS The proposed algorithm using Mask R-CNN can accurately track the needle feature tip and axis on MR images from in vivo intra-procedural prostate biopsy cases and ex vivo real-time MRI experiments with a range of different conditions. The algorithm achieved pixel-level tracking accuracy in real time and has potential to assist MRI-guided percutaneous interventions.
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Affiliation(s)
- Xinzhou Li
- Department of Radiological Sciences, University of California Los Angeles, 300 UCLA Medical Plaza, Suite B119, Los Angeles, CA, 90095, USA
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA, USA
| | - Adam S Young
- Department of Radiological Sciences, University of California Los Angeles, 300 UCLA Medical Plaza, Suite B119, Los Angeles, CA, 90095, USA
| | - Steven S Raman
- Department of Radiological Sciences, University of California Los Angeles, 300 UCLA Medical Plaza, Suite B119, Los Angeles, CA, 90095, USA
| | - David S Lu
- Department of Radiological Sciences, University of California Los Angeles, 300 UCLA Medical Plaza, Suite B119, Los Angeles, CA, 90095, USA
| | - Yu-Hsiu Lee
- Department of Mechanical and Aerospace Engineering, University of California Los Angeles, Los Angeles, CA, USA
| | - Tsu-Chin Tsao
- Department of Mechanical and Aerospace Engineering, University of California Los Angeles, Los Angeles, CA, USA
| | - Holden H Wu
- Department of Radiological Sciences, University of California Los Angeles, 300 UCLA Medical Plaza, Suite B119, Los Angeles, CA, 90095, USA.
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA, USA.
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Verification of needle guidance accuracy in pelvic phantom using registered ultrasound and MRI images for intracavitary/interstitial gynecologic brachytherapy. J Contemp Brachytherapy 2020; 12:147-159. [PMID: 32395139 PMCID: PMC7207233 DOI: 10.5114/jcb.2020.94583] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 03/17/2020] [Indexed: 12/24/2022] Open
Abstract
Purpose In combined intracavitary/interstitial (IC/IS) gynecologic brachytherapy, trackers attached to interstitial needles of localize real-time needle trajectories, and intraoperative ultrasound (US) images provide updated anatomy information during needle insertions. To achieve an effective visualization and image guidance, real-time needle trajectories and US images can be unified in preoperative magnetic resonance imaging (MRI) image space together. This study evaluates the rigid registration accuracy between US images and MRI images as well as the registration accuracy between US images and real-time needle trajectories in a pelvic phantom. Material and methods A method for US probe calibration and accomplished rigid registration between MRI images and US images was proposed. An IC/IS applicator was designed. Micro electromagnetic sensor to track and localize real-time needle trajectories in 3D MRI image space was used. Marker validation to test the accuracy of US probe calibration and pelvic phantom validation to test the registration accuracy between US images and MRI images was conducted as well as and pelvic phantom study to verify the registration accuracy between real-time needle trajectories and needle trajectories in registered US images. Results US probe calibration accuracy was 0.80 ±0.23 mm (n = 60). Registration accuracy between US images and MRI images were 1.01 ±0.22 mm in the axial plane (n = 60) and 1.14 ±0.20 mm in the sagittal plane (n = 24). Registration accuracy between real-time needle trajectories and needle trajectories in registered US images were 1.25 ±0.31 mm (n = 40) and 1.61 ±0.28 degrees (n = 5), respectively. Conclusions In this study, we showed that under ideal conditions, rigid registration between MRI images and US images obtained high accuracy for real-time image guidance. Additionally, registered US images provided accurate image guidance during visual needle insertion in IC/IS gynecologic brachytherapy to achieve a combination of effective visualization and image guidance.
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Zhang H, Donnelly ED, Strauss JB, Kang Z, Gopalakrishnan M, Lee PC, Khelashvili G, Nair CK, Lee BH, Sathiaseelan V. Clinical implementation, logistics and workflow guide for MRI image based interstitial HDR brachytherapy for gynecological cancers. J Appl Clin Med Phys 2019; 20:37-49. [PMID: 31600015 PMCID: PMC6839385 DOI: 10.1002/acm2.12736] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/25/2019] [Accepted: 09/04/2019] [Indexed: 11/07/2022] Open
Abstract
Interstitial brachytherapy (IBT) is often utilized to treat women with bulky endometrial or cervical cancers not amendable to intracavitary treatments. A modern trend in IBT is the utilization of magnetic resonance imaging (MRI) with a high dose rate (HDR) afterloader for conformal 3D image-based treatments. The challenging part of this procedure is to properly complete many sequenced and co-related physics preparations. We presented the physics preparations and clinical workflow required for implementing MRI-based HDR IBT (MRI-HDR-IBT) of gynecologic cancer patients in a high-volume brachytherapy center. The present document is designed to focus on the clinical steps required from a physicist's standpoint. Those steps include: (a) testing IBT equipment with MRI scanner, (b) preparation of templates and catheters, (c) preparation of MRI line markers, (d) acquisition, importation and registration of MRI images, (e) development of treatment plans and (f) treatment evaluation and documentation. The checklists of imaging acquisition, registration and plan development are also presented. Based on the TG-100 recommendations, a workflow chart, a fault tree analysis and an error-solution table listing the speculated errors and solutions of each step are provided. Our workflow and practice indicated the MRI-HDR-IBT is achievable in most radiation oncology clinics if the following equipment is available: MRI scanner, CT (computed tomography) scanner, MRI/CT compatible templates and applicators, MRI line markers, HDR afterloader and a brachytherapy treatment planning system capable of utilizing MRI images. The OR/procedure room availability and anesthesiology support are also important. The techniques and approaches adopted from the GEC-ESTRO (Groupe Européen de Curiethérapie - European Society for Therapeutic Radiology and Oncology) recommendations and other publications are proven to be feasible. The MRI-HDR-IBT program can be developed over time and progressively validated through clinical experience, this document is expected to serve as a reference workflow guideline for implementing and performing the procedure.
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Affiliation(s)
- Hualin Zhang
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
| | - Eric D Donnelly
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
| | - Jonathan B Strauss
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
| | - Zhuang Kang
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
| | - Mahesh Gopalakrishnan
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
| | - Plato C Lee
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
| | - Gocha Khelashvili
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
| | - Chithra K Nair
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
| | - Brian H Lee
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
| | - Vythialingam Sathiaseelan
- Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL, USA
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Kawabata I, Imai H, Kanno Z, Tetsumura A, Tsutsumi Y, Doi H, Ashida M, Kurabayashi T, Hanawa T, Yamamoto T, Ono T. Three-dimensional quantification of magnetic resonance imaging artifacts associated with shape factors. Dent Mater J 2019; 38:638-645. [PMID: 31178545 DOI: 10.4012/dmj.2018-197] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Differences in the volumes of artifacts caused by variously shaped titanium objects on magnetic resonance imaging (MRI) were evaluated. Spherical-, square cubic-, and regular tetrahedron-shaped isotropic, and elongated spherical-, elongated cubic-, and elongated tetrahedron-shaped anisotropic objects, with identical volumes, were prepared. Samples were placed on a nickel-doped agarose gel phantom and covered with nickel-nitrate hexahydrate solution. Three-Tesla MR images were obtained using turbo spin echo and gradient echo sequences. Areas with ±30% of the signal intensity of the standard background value were considered artifacts. Sample volumes were deducted from these volumes to calculate the total artifact volumes. Isotropic samples had similar artifact volumes. For anisotropic samples, the artifact volume increased in proportion with the normalized projection area. MRI artifact size can be reduced by high anisotropic designs, and by positioning the long axis of the metal device as parallel as possible to the magnetic field axis.
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Affiliation(s)
- Iku Kawabata
- Department of Orthodontic Science, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University
| | - Haruki Imai
- Department of Orthodontic Science, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University
| | - Zuisei Kanno
- Department of Orthodontic Science, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University
| | - Akemi Tetsumura
- Department of Dental Radiology and Radiation Research, Faculty of Dentistry, Tokyo Medical and Dental University
| | - Yusuke Tsutsumi
- Department of Metallic Biomaterials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU)
| | - Hisashi Doi
- Department of Metallic Biomaterials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU)
| | - Maki Ashida
- Department of Metallic Biomaterials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU)
| | - Tohru Kurabayashi
- Department of Dental Radiology and Radiation Research, Faculty of Dentistry, Tokyo Medical and Dental University
| | - Takao Hanawa
- Department of Metallic Biomaterials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU)
| | - Toru Yamamoto
- Graduate School of Health Sciences, Hokkaido University
| | - Takashi Ono
- Department of Orthodontic Science, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University
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13
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Vafay Eslahi S, Ji J. Accelerated positive contrast MRI of interventional devices using parallel compressed sensing imaging. Magn Reson Imaging 2019; 60:130-136. [PMID: 31028791 DOI: 10.1016/j.mri.2019.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/04/2019] [Accepted: 04/06/2019] [Indexed: 11/24/2022]
Abstract
Susceptibility-based magnetic resonance imaging (MRI) method can image small MR-compatible devices with positive contrast. However, the relatively long data acquisition time required by the method hinders its practical applications. This study presents a parallel compressive sensing technique with a modified fast spin echo to accelerate data acquisition for the susceptibility-based positive contrast MRI. The method integrates the generalized autocalibrating partially parallel acquisitions and the compressive sensing techniques in the reconstruction algorithm. MR imaging data acquired from several phantoms containing interventional devices such as biopsy needles, stent, and brachytherapy seeds, used for validating the proposed technique. The results show that it can speed up data acquisition by a factor of about five while preserving the quality of the positive contrast images.
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Affiliation(s)
- Samira Vafay Eslahi
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
| | - Jim Ji
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA.
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14
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Weber H, Hargreaves BA, Daniel BL. Artifact-reduced imaging of biopsy needles with 2D multispectral imaging. Magn Reson Med 2017; 80:655-661. [PMID: 29285787 DOI: 10.1002/mrm.27056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 11/30/2017] [Accepted: 12/01/2017] [Indexed: 12/28/2022]
Abstract
PURPOSE Magnetic resonance (MR) guidance for biopsy procedures requires high intrinsic soft-tissue contrast. However, artifacts induced by the metallic needle can reduce its localization and require low-susceptibility needle materials with poorer cutting performance. In a proof of concept, we demonstrate the feasibility of 2D multispectral imaging (2DMSI) for both needle tracking and for needle artifact reduction for more precise needle localization and to enable the usage of needle materials with higher susceptibility. METHOD We applied 2DMSI for imaging of MR-compatible biopsy needles, conventional stainless-steel needles, and mixed-material needles and compared it to conventional techniques. In addition, we exploited intrinsic off-resonance information for passive needle tracking. RESULTS 2DMSI achieved a stronger reduction of the needle artifact compared to conventional techniques. For the mixed-material needles, the artifact was reduced to a level below that for MR-compatible needles with conventional imaging. The passive tracking also improved the ability to pinpoint the needle. CONCLUSION 2DMSI is promising for both needle tracking and artifact-reduced imaging of biopsy needles for a more precise needle localization. 2DMSI may be particularly promising for needles inducing large distortions or for targeting of small lesions. In addition, it may enable the use of needle materials with higher susceptibility and potentially better sampling performance. Magn Reson Med 80:655-661, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Hans Weber
- Department of Radiology, Stanford University, Palo Alto, California, USA
| | - Brian A Hargreaves
- Department of Radiology, Stanford University, Palo Alto, California, USA
| | - Bruce L Daniel
- Department of Radiology, Stanford University, Palo Alto, California, USA
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15
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Schleicher KE, Bock M, Düring K, Kroboth S, Krafft AJ. Radial MRI with variable echo times: reducing the orientation dependency of susceptibility artifacts of an MR-safe guidewire. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2017; 31:235-242. [PMID: 28770356 DOI: 10.1007/s10334-017-0645-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 07/20/2017] [Accepted: 07/21/2017] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Guidewires are indispensable tools for intravascular MR-guided interventions. Recently, an MR-safe guidewire made from a glass-fiber/epoxy compound material with embedded iron particles was developed. The size of the induced susceptibility artifact, and thus the guidewire's visibility, depends on its orientation against B 0. We present a radial acquisition scheme with variable echo times that aims to reduce the artifact's orientation dependency. MATERIALS AND METHODS The radial acquisition scheme uses sine-squared modulated echo times depending on the physical direction of the spoke to balance the susceptibility artifact of the guidewire. The acquisition scheme was studied in simulations based on dipole fields and in phantom experiments for different orientations of the guidewire against B 0. The simulated and measured artifact widths were quantitatively compared. RESULTS Compared to acquisitions with non-variable echo times, the proposed acquisition scheme shows a reduced angular variability. For the two main orientations (i.e., parallel and perpendicular to B 0), the ratio of the artifact widths was reduced from about 2.2 (perpendicular vs. parallel) to about 1.2 with the variable echo time approach. CONCLUSION The reduction of the orientation dependency of the guidewire's artifact via sine-squared varying echo times could be verified in simulations and measurements. The more balanced artifact allows for a better overall visibility of the guidewire.
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Affiliation(s)
- Katharina E Schleicher
- Department of Radiology, Medical Physics, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 60a, 79106, Freiburg, Germany.
| | - Michael Bock
- Department of Radiology, Medical Physics, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 60a, 79106, Freiburg, Germany
| | | | - Stefan Kroboth
- Department of Radiology, Medical Physics, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 60a, 79106, Freiburg, Germany
| | - Axel J Krafft
- Department of Radiology, Medical Physics, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Strasse 60a, 79106, Freiburg, Germany
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16
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Hargreaves BA, Taviani V, Litwiller DV, Yoon D. 2D multi-spectral imaging for fast MRI near metal. Magn Reson Med 2017; 79:968-973. [PMID: 28444805 DOI: 10.1002/mrm.26724] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/07/2017] [Accepted: 03/29/2017] [Indexed: 01/19/2023]
Abstract
PURPOSE To develop a fast 2D method for MRI near metal with reduced B0 in-plane and through-slice artifacts. METHODS Multi-spectral imaging (MSI) approaches reduce artifacts in MR images near metal, but require 3D imaging of multiple excited volumes regardless of imaging geometry or artifact severity. The proposed 2D MSI method rapidly excites a limited slice and spectral region using gradient reversal between excitation and refocusing pulses, then uses standard 2D imaging, with the process repeating to cover multiple spectral offsets that are combined as in other MSI techniques. 2D MSI was implemented in a spin-echo-train sequence and validated in phantoms and in vivo by comparing it with standard spin-echo imaging and existing MSI techniques. RESULTS 2D MSI images for each spatial-spectral region follow isocontours of the dipole-like B0 field variation, and thus frequency variation, near metal devices. Artifact correction in phantoms and human subjects with metal is comparable to 3D MSI methods, and superior to standard spin-echo techniques. Scan times are reduced compared with 3D MSI methods in cases where a limited number of slices are needed, though signal-to-noise ratio is also reduced as expected. CONCLUSION 2D MSI offers a fast and flexible alternative to 3D MSI for artifact reduction near metal. Magn Reson Med 79:968-973, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Brian A Hargreaves
- Department of Radiology, Stanford University, Stanford, California, USA.,Department of Bioengineering, Stanford University, Stanford, California, USA.,Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | | | | | - Daehyun Yoon
- Department of Radiology, Stanford University, Stanford, California, USA
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17
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Shi C, Xie G, Zhang Y, Zhang X, Chen M, Su S, Dong Y, Liu X, Ji J. Accelerated susceptibility-based positive contrast imaging of MR compatible metallic devices based on modified fast spin echo sequences. Phys Med Biol 2017; 62:2505-2520. [DOI: 10.1088/1361-6560/aa5fa3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Wang W, Viswanathan AN, Damato AL, Chen Y, Tse Z, Pan L, Tokuda J, Seethamraju RT, Dumoulin CL, Schmidt EJ, Cormack RA. Evaluation of an active magnetic resonance tracking system for interstitial brachytherapy. Med Phys 2016; 42:7114-21. [PMID: 26632065 DOI: 10.1118/1.4935535] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE In gynecologic cancers, magnetic resonance (MR) imaging is the modality of choice for visualizing tumors and their surroundings because of superior soft-tissue contrast. Real-time MR guidance of catheter placement in interstitial brachytherapy facilitates target coverage, and would be further improved by providing intraprocedural estimates of dosimetric coverage. A major obstacle to intraprocedural dosimetry is the time needed for catheter trajectory reconstruction. Herein the authors evaluate an active MR tracking (MRTR) system which provides rapid catheter tip localization and trajectory reconstruction. The authors assess the reliability and spatial accuracy of the MRTR system in comparison to standard catheter digitization using magnetic resonance imaging (MRI) and CT. METHODS The MRTR system includes a stylet with microcoils mounted on its shaft, which can be inserted into brachytherapy catheters and tracked by a dedicated MRTR sequence. Catheter tip localization errors of the MRTR system and their dependence on catheter locations and orientation inside the MR scanner were quantified with a water phantom. The distances between the tracked tip positions of the MRTR stylet and the predefined ground-truth tip positions were calculated for measurements performed at seven locations and with nine orientations. To evaluate catheter trajectory reconstruction, fifteen brachytherapy catheters were placed into a gel phantom with an embedded catheter fixation framework, with parallel or crossed paths. The MRTR stylet was then inserted sequentially into each catheter. During the removal of the MRTR stylet from within each catheter, a MRTR measurement was performed at 40 Hz to acquire the instantaneous stylet tip position, resulting in a series of three-dimensional (3D) positions along the catheter's trajectory. A 3D polynomial curve was fit to the tracked positions for each catheter, and equally spaced dwell points were then generated along the curve. High-resolution 3D MRI of the phantom was performed followed by catheter digitization based on the catheter's imaging artifacts. The catheter trajectory error was characterized in terms of the mean distance between corresponding dwell points in MRTR-generated catheter trajectory and MRI-based catheter digitization. The MRTR-based catheter trajectory reconstruction process was also performed on three gynecologic cancer patients, and then compared with catheter digitization based on MRI and CT. RESULTS The catheter tip localization error increased as the MRTR stylet moved further off-center and as the stylet's orientation deviated from the main magnetic field direction. Fifteen catheters' trajectories were reconstructed by MRTR. Compared with MRI-based digitization, the mean 3D error of MRTR-generated trajectories was 1.5 ± 0.5 mm with an in-plane error of 0.7 ± 0.2 mm and a tip error of 1.7 ± 0.5 mm. MRTR resolved ambiguity in catheter assignment due to crossed catheter paths, which is a common problem in image-based catheter digitization. In the patient studies, the MRTR-generated catheter trajectory was consistent with digitization based on both MRI and CT. CONCLUSIONS The MRTR system provides accurate catheter tip localization and trajectory reconstruction in the MR environment. Relative to the image-based methods, it improves the speed, safety, and reliability of the catheter trajectory reconstruction in interstitial brachytherapy. MRTR may enable in-procedural dosimetric evaluation of implant target coverage.
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Affiliation(s)
- Wei Wang
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts 02115 and Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Akila N Viswanathan
- Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Antonio L Damato
- Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Yue Chen
- Department of Engineering, The University of Georgia, Athens, Georgia 30602
| | - Zion Tse
- Department of Engineering, The University of Georgia, Athens, Georgia 30602
| | - Li Pan
- Siemens Healthcare USA, Baltimore, Maryland 21287
| | - Junichi Tokuda
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | | | - Charles L Dumoulin
- Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
| | - Ehud J Schmidt
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Robert A Cormack
- Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, Massachusetts 02115
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Ji J. MRI of biopsy needles by susceptibility mapping based on Wiener filter F and L1-regularization. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:1576-9. [PMID: 26736574 DOI: 10.1109/embc.2015.7318674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Biopsy needles are devices that have been used for intravenous therapy. However, the high susceptibility of needles results in signal loss and distortion which makes the location of needles hard to identify in the MRI images. A variety of approaches has been proposed to quantify the susceptibility of the materials being imaged because susceptibility is an intrinsic property that can be used to make a good contrast between different materials. Although previous techniques on susceptibility mapping seem quite effective, they usually consume too much time due to the iterations. In this paper, a method based on Wiener filter is developed to improve the speed of susceptibility mapping. Simulation and phantom experiment demonstrate the effectiveness and high efficiency of the proposed method.
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20
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Heinrich A, Teichgräber UK, Güttler FV. Measurement of susceptibility artifacts with histogram-based reference value on magnetic resonance images according to standard ASTM F2119. ACTA ACUST UNITED AC 2015; 60:541-9. [DOI: 10.1515/bmt-2014-0184] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 04/17/2015] [Indexed: 11/15/2022]
Abstract
AbstractThe standard ASTM F2119 describes a test method for measuring the size of a susceptibility artifact based on the example of a passive implant. A pixel in an image is considered to be a part of an image artifact if the intensity is changed by at least 30% in the presence of a test object, compared to a reference image in which the test object is absent (reference value). The aim of this paper is to simplify and accelerate the test method using a histogram-based reference value.Four test objects were scanned parallel and perpendicular to the main magnetic field, and the largest susceptibility artifacts were measured using two methods of reference value determination (reference image-based and histogram-based reference value). The results between both methods were compared using the Mann-Whitney U-test.The difference between both reference values was 42.35±23.66. The difference of artifact size was 0.64±0.69 mm. The artifact sizes of both methods did not show significant differences; the p-value of the Mann-Whitney U-test was between 0.710 and 0.521.A standard-conform method for a rapid, objective, and reproducible evaluation of susceptibility artifacts could be implemented. The result of the histogram-based method does not significantly differ from the ASTM-conform method.
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21
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Marami B, Sirouspour S, Capson DW. Non-rigid registration of medical images based on estimation of deformation states. Phys Med Biol 2014; 59:6891-921. [DOI: 10.1088/0031-9155/59/22/6891] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Wireless mobile technology to improve workflow and feasibility of MR-guided percutaneous interventions. Int J Comput Assist Radiol Surg 2014; 10:665-76. [PMID: 25179151 DOI: 10.1007/s11548-014-1109-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 08/10/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE A wireless interactive display and control device combined with a platform-independent web-based user interface (UI) was developed to improve the workflow for interventional magnetic resonance imaging (iMRI). METHODS The iMRI-UI enables image acquisition of up to three independent slices using various pulse sequences with different contrast weighting. Pulse sequence, scan geometry and related parameters can be changed on the fly via the iMRI-UI using a tablet computer for improved lesion detection and interventional device targeting. The iMRI-UI was validated for core biopsies with a liver phantom ([Formula: see text] [Formula: see text] 40) and Thiel soft-embalmed human cadavers ([Formula: see text] [Formula: see text] 24) in a clinical 1.5T MRI scanner. RESULTS The iMRI-UI components and setup were tested and found conditionally MRI-safe to use according to current ASTM standards. Despite minor temporary touch screen interference at a close distance to the bore ([Formula: see text]20 cm), no other issues regarding quality or imaging artefacts were observed. The 3D root-mean-square distance error was [Formula: see text] (phantom)/[Formula: see text] mm (cadaver), and overall procedure times ranged between 12 and 22 (phantom)/20 and 55 min (cadaver). CONCLUSION The wireless iMRI-UI control setup enabled fast and accurate interventional biopsy needle placements along complex trajectories and improved the workflow for percutaneous interventions under MRI guidance in a preclinical trial.
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Eibofner F, Wojtczyk H, Graf H, Clasen S. Magnetic resonance visualization of conductive structures by sequence-triggered direct currents and spin-echo phase imaging. Med Phys 2014; 41:062301. [PMID: 24877833 DOI: 10.1118/1.4875679] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Instrument visualization in interventional magnetic resonance imaging (MRI) is commonly performed via susceptibility artifacts. Unfortunately, this approach suffers from limited conspicuity in inhomogeneous tissue and disturbed spatial encoding. Also, susceptibility artifacts are controllable only by sequence parameters. This work presents the basics of a new visualization method overcoming such problems by applying sequence-triggered direct current (DC) pulses in spin-echo (SE) imaging. SE phase images allow for background free current path localization. METHODS Application of a sequence-triggered DC pulse in SE imaging, e.g., during a time period between radiofrequency excitation and refocusing, results in transient field inhomogeneities. Dependent on the additional z-magnetic field from the DC, a phase offset results despite the refocusing pulse. False spatial encoding is avoided by DC application during periods when read-out or slice-encoding gradients are inactive. A water phantom containing a brass conductor (water equivalent susceptibility) and a titanium needle (serving as susceptibility source) was used to demonstrate the feasibility. Artifact dependence on current strength and orientation was examined. RESULTS Without DC, the brass conductor was only visible due to its water displacement. The titanium needle showed typical susceptibility artifacts. Applying triggered DC pulses, the phase offset of spins near the conductor appeared. Because SE phase images are homogenous also in regions of persistent field inhomogeneities, the position of the conductor could be determined with high reliability. Artifact characteristic could be easily controlled by amperage leaving sequence parameters unchanged. For an angle of 30° between current and static field visualization was still possible. CONCLUSIONS SE phase images display the position of a conductor carrying pulsed DC free from artifacts caused by persistent field inhomogeneities. Magnitude and phase images are acquired simultaneously under the same conditions without the use of extra measurement time. The presented technique offers many advantages for precise instrument localization in interventional MRI.
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Affiliation(s)
- Frank Eibofner
- Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076, Germany
| | - Hanne Wojtczyk
- Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076, Germany
| | - Hansjörg Graf
- Section on Experimental 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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Abstract
The indications, technique, results and limitations of MRI vacuum-assisted breast biopsies are discussed from a review of the literature. This was initially a home-grown technique and its development was slowed down by several factors. As a result of major technical advances, it has become a reliable and very consistent procedure with a low rate of underestimation. It is now an undisputed technique when suspicious MRI enhancement is seen with no corresponding mammography or ultrasound features.
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Affiliation(s)
- R Plantade
- Nice Europe Imaging Centre, 15, rue Alberti, 06000 Nice, France.
| | - I Thomassin-Naggara
- Department of Radiology, Tenon Hospital, Paris Public Hospitals Health Service (AP-HP), Pierre et Marie Curie University Oncology Institute, 4, rue de la Chine, 75020 Paris, France
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Penzkofer T, Peykan N, Schmidt K, Krombach G, Kuhl CK. How MRI compatible is "MRI compatible"? A systematic comparison of artifacts caused by biopsy needles at 3.0 and 1.5 T. Cardiovasc Intervent Radiol 2013; 36:1646-1657. [PMID: 23580119 DOI: 10.1007/s00270-013-0616-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 02/15/2013] [Indexed: 11/25/2022]
Abstract
PURPOSE This study was designed to systematically investigate artifacts caused by interventional needles recommended for use in MRI, with focus on field strength, needle/mandrin type, orientation and sequence. METHODS Eight different MRI compatible needles were placed in porcine tissue and examined at 1.5 and 3.0 T with balanced-steady-state-free-precession (B-SSFP) and T1-weighted-spoiled-gradient-echo (T1-SPGR) sequences in different orientations to B0. Artifact diameters with regards to the primary, inner, and secondary, outer artifacts were assessed and statistically evaluated. RESULTS The types and degree of artifacts varied considerably, especially between different mandrin types even for the same needles. Orientation of the needle in the magnetic field was another main contributor to the artifact dimensions. Less important factors were the type of pulse sequence and field strength. Artifacts ranged from 0.7 mm (steel, 0°, B-SSFP, 3.0 T, inner) to 71.4 mm (nitinol, 90°, B-SSFP, 1.5 T, outer). Inner artifact diameters in B-SSFP were slightly larger (8.2 ± 5.7 mm) than those in T1-SPGR (7.6 ± 5.4 mm) and comparable between 1.5 and 3.0 T (e.g., 8.0 vs. 8.4 mm, B-SSFP). CONCLUSIONS Although all were sold as "MR compatible," the artifacts differed greatly between needle types, and even more so for different mandrins. The results suggest an empirical approach to the needle choice based on lesion type and approach angle.
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Affiliation(s)
- Tobias Penzkofer
- Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Pauwelsstr. 30, Aachen, 52074, Germany. .,Surgical Planning Lab, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA.
| | - Nilufar Peykan
- Klinikum Osnabrück, Röntgen- und Strahlenklinik, Am Finkenhügel 1, 49076, Osnabrück, Germany
| | - Katja Schmidt
- Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Pauwelsstr. 30, Aachen, 52074, Germany
| | - Gabriele Krombach
- Department of Radiology, Justus-Liebig University Gießen, Klinikstrasse 3, 35392, Giessen, Germany
| | - Christiane K Kuhl
- Department of Diagnostic and Interventional Radiology, RWTH Aachen University Hospital, Pauwelsstr. 30, Aachen, 52074, Germany
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de Leeuw H, Seevinck PR, Bakker CJG. Center-out radial sampling with off-resonant reconstruction for efficient and accurate localization of punctate and elongated paramagnetic structures. Magn Reson Med 2012; 69:1611-22. [DOI: 10.1002/mrm.24416] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 05/17/2012] [Accepted: 06/24/2012] [Indexed: 11/06/2022]
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Jia F, Kumar R, Korvink JG. Optimal magnetic susceptibility matching in 3D. Magn Reson Med 2012; 69:1146-56. [DOI: 10.1002/mrm.24323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 04/10/2012] [Accepted: 04/11/2012] [Indexed: 11/11/2022]
Affiliation(s)
- Feng Jia
- Freiburg Institute of Advanced Studies (FRIAS); University of Freiburg; Freiburg Germany
| | - Rajesh Kumar
- Freiburg Institute of Advanced Studies (FRIAS); University of Freiburg; Freiburg Germany
| | - Jan G. Korvink
- Freiburg Institute of Advanced Studies (FRIAS); University of Freiburg; Freiburg Germany
- Laboratory for Simulation; Department of Microsystems Engineering (IMTEK); University of Freiburg; Freiburg Germany
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Saikus CE, Ratnayaka K, Barbash IM, Colyer JH, Kocaturk O, Faranesh AZ, Lederman RJ. MRI-guided vascular access with an active visualization needle. J Magn Reson Imaging 2011; 34:1159-66. [PMID: 22006552 PMCID: PMC3201741 DOI: 10.1002/jmri.22715] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To develop an approach to vascular access under magnetic resonance imaging (MRI), as a component of comprehensive MRI-guided cardiovascular catheterization and intervention. MATERIALS AND METHODS We attempted jugular vein access in healthy pigs as a model of "difficult" vascular access. Procedures were performed under real-time MRI guidance using reduced field of view imaging. We developed an "active" MRI antenna-needle having an open-lumen, distinct tip appearance and indicators of depth and trajectory in order to enhance MRI visibility during the procedure. We compared performance of the active needle against an unmodified commercial passively visualized needle, measured by procedure success among operators with different levels of experience. RESULTS MRI-guided central vein access was feasible using both the active needle and the unmodified passive needle. The active needle required less time (88 vs. 244 sec, P = 0.022) and fewer needle passes (4.5 vs. 9.1, P = 0.028), irrespective of operator experience. CONCLUSION MRI-guided access to central veins is feasible in our animal model. When image guidance is necessary for vascular access, performing this component under MRI will allow wholly MRI-guided catheterization procedures that do not require adjunctive imaging facilities such as x-ray or ultrasound. The active needle design showed enhanced visibility, as expected. These capabilities may permit more complex catheter-based cardiovascular interventional procedures enabled by enhanced image guidance.
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Affiliation(s)
- Christina E Saikus
- Cardiovascular and Pulmonary Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-1061, USA
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Thomas C, Wojtczyk H, Rempp H, Clasen S, Horger M, von Lassberg C, Fritz J, Claussen CD, Pereira PL. Carbon fibre and nitinol needles for MRI-guided interventions: First in vitro and in vivo application. Eur J Radiol 2011; 79:353-8. [DOI: 10.1016/j.ejrad.2010.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 07/02/2010] [Accepted: 07/07/2010] [Indexed: 10/19/2022]
Affiliation(s)
- Christoph Thomas
- Department of Diagnostic and Interventional Radiology, University of Tübingen, Tübingen, Germany.
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Rump JC, Jonczyk M, Seebauer CJ, Streitparth F, Güttler FV, Teichgräber UKM, Hamm B. Reduced k-space acquisition to accelerate MR imaging of moving interventional instruments: a phantom study. Int J Comput Assist Radiol Surg 2011; 6:713-9. [PMID: 21416136 DOI: 10.1007/s11548-011-0554-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 03/02/2011] [Indexed: 11/24/2022]
Abstract
PURPOSE The goal of this study was to investigate the impact of reduced k-space sampling rates on the visualization of a moving MR-compatible puncture needle and to demonstrate the feasibility of keyhole imaging in interventional magnetic resonance imaging (MRI). MATERIAL AND METHODS All experiments were performed in an open 1.0 Tesla MRI. MR images of a moving puncture needle were taken with different keyhole sampling rates from 15-100%, in 10% increments. The needle was submerged in a water-filled basin and was imaged in motion with a T1-weighted gradient-echo sequence with an initial acquisition rate of 1.4 s per image. An apparatus operated by a compressor unit enabled needle rotation and ensured reproducible needle movements. The median forward velocity of the needle tip was 2 cm/s. To evaluate the depiction of the needle, artifact diameter of the needle, contrast-to-noise ratio (CNR), and needle tip profiles (delineation) were measured. RESULTS The needle position was determined with an longitudinal error of 3 mm and a transverse error of 0.8 mm with respect to the needle's orientation and the theoretically calculated trajectory. No significant correlation was found between the CNR and velocity. A reduction of k-space update rates caused neither a significant reduction of CNR nor a significant increase in artifact diameter or blurring of the needle profile. CONCLUSION The application of keyhole imaging with update rates of greater than 15% is sufficient for the MR guidance of interventions with an signal-to-noise ratio >9 of the surrounding tissue and a target accuracy of >1 mm. Keyhole imaging can increase temporal resolution while ensuring unimpaired spatial resolution and image quality of the depicted instrument.
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Magnetic resonance-guided upper abdominal biopsies in a high-field wide-bore 3-T MRI system: feasibility, handling, and needle artefacts. Eur Radiol 2010; 20:2414-21. [PMID: 20503050 DOI: 10.1007/s00330-010-1809-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2010] [Accepted: 03/15/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE To investigate the feasibility and handling of abdominal MRI-guided biopsies in a 3-T MRI system. METHODS Over a 1-year period, 50 biopsies were obtained in 47 patients with tumours of the upper abdominal organs guided by 3-T MRI with a large-bore diameter of 70 cm. Lesions in liver (47), spleen (1) and kidney (2) were biopsied with a coaxial technique using a 16-G biopsy needle guided by a T1-weighted three-dimensional gradient recalled echo volumetric interpolated breath-hold examination (T1w-3D-GRE-VIBE) sequence. Sensitivity, specificity, accuracy, complication rate, interventional complexity, room/intervention time and needle artefacts were determined. RESULTS A sensitivity of 0.93, specificity of 1.0 and accuracy of 0.94 were observed. Three patients required a rebiopsy. There was a minor complications rate of 13.6%, and no major complications were observed. Histopathology revealed 38 malignant lesions, and 3-month follow-up confirmed 9 benign lesions. Mean lesion diameter was 3.4 ± 3.1 cm (50% being smaller than 2 cm). Mean needle tract length was 10.8 ± 3.3 cm. Median room time was 42.0 ± 19.8 min and intervention time 9.3 ± 8.1 min. Needle artefact size was about 9-fold greater for perpendicular access versus access parallel to the main magnetic field. CONCLUSION Biopsies of the upper abdomen can be performed with great technical success and easy handling because of the large-bore diameter. The MRI-guided biopsy needle had an acceptable susceptibility artefact at 3 T. However future research must aim to reduce the susceptibility effects of the biopsy systems.
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Thomas C, Springer F, Röthke M, Rempp H, Clasen S, Fritz J, Claussen CD, Pereira PL. In Vitro Assessment of Needle Artifacts with an Interactive Three-dimensional MR Fluoroscopy System. J Vasc Interv Radiol 2010; 21:375-80. [DOI: 10.1016/j.jvir.2009.11.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2009] [Revised: 11/08/2009] [Accepted: 11/11/2009] [Indexed: 01/20/2023] Open
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Wonneberger U, Schnackenburg B, Streitparth F, Walter T, Rump J, Teichgräber UKM. Evaluation of magnetic resonance imaging-compatible needles and interactive sequences for musculoskeletal interventions using an open high-field magnetic resonance imaging scanner. Cardiovasc Intervent Radiol 2009; 33:346-51. [PMID: 19705200 DOI: 10.1007/s00270-009-9676-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 07/09/2009] [Accepted: 07/13/2009] [Indexed: 11/27/2022]
Abstract
In this article, we study in vitro evaluation of needle artefacts and image quality for musculoskeletal laser-interventions in an open high-field magnetic resonance imaging (MRI) scanner at 1.0T with vertical field orientation. Five commercially available MRI-compatible puncture needles were assessed based on artefact characteristics in a CuSO4 phantom (0.1%) and in human cadaveric lumbar spines. First, six different interventional sequences were evaluated with varying needle orientation to the main magnetic field B0 (0 degrees to 90 degrees ) in a sequence test. Artefact width, needle-tip error, and contrast-to-noise ratio (CNR) were calculated. Second, a gradient-echo sequence used for thermometric monitoring was assessed and in varying echo times, artefact width, tip error, and signal-to-noise ratio (SNR) were measured. Artefact width and needle-tip error correlated with needle material, instrument orientation to B0, and sequence type. Fast spin-echo sequences produced the smallest needle artefacts for all needles, except for the carbon fibre needle (width <3.5 mm, tip error <2 mm) at 45 degrees to B0. Overall, the proton density-weighted spin-echo sequences had the best CNR (CNR(Muscle/Needle) >16.8). Concerning the thermometric gradient echo sequence, artefacts remained <5 mm, and the SNR reached its maximum at an echo time of 15 ms. If needle materials and sequences are accordingly combined, guidance and monitoring of musculoskeletal laser interventions may be feasible in a vertical magnetic field at 1.0T.
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Affiliation(s)
- Uta Wonneberger
- Department of Radiology, Charité, University Medicine Berlin, Charitéplatz 1, 10117 Berlin, Germany.
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Wendt M, Zhang Q, Melzer A, Dupont E, Lewin JS, Duerk JL. Visualisation, tracking and navigation of instruments for MRI-guided interventional procedures. MINIM INVASIV THER 2009. [DOI: 10.3109/13645709909153181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Kettenbach J, Kacher DF, Kanan AR, Rostenberg B, Fairhurst J, Stadler A, Kienreich K, Jolesz FA. Intraoperative and interventional MRI: Recommendations for a safe environment. MINIM INVASIV THER 2009; 15:53-64. [PMID: 16754187 DOI: 10.1080/13645700600640774] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
In this paper we report on current experience and review magnetic resonance safety protocols and literature in order to define practices surrounding MRI-guided interventional and surgical procedures. Direct experience, the American College of Radiology White paper on MR Safety, and various other sources are summarized. Additional recommendations for interventional and surgical MRI-guided procedures cover suite location/layout, accessibility, safety policy, personnel training, and MRI compatibility issues. Further information is freely available for sites to establish practices to minimize risk and ensure safety. Interventional and intraoperative MRI is emerging from its infancy, with twelve years since the advent of the field and well over 10,000 cases collectively performed. Thus, users of interventional and intraoperative MRI should adapt guidelines utilizing universal standards and terminology and establish a site-specific policy. With policy enforcement and proper training, the interventional and intraoperative MR imaging suite can be a safe and effective environment.
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Affiliation(s)
- Joachim Kettenbach
- Department of Radiology, Medical University Vienna, General Hospital, Vienna, Austria.
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Feasibility of Real-Time Magnetic Resonance–Guided Angioplasty and Stenting of Renal Arteries in Vitro and in Swine, Using a New Polyetheretherketone-Based Magnetic Resonance–Compatible Guidewire. Invest Radiol 2009; 44:234-41. [DOI: 10.1097/rli.0b013e31819b00f1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Müller-Bierl BM, Martirosian P, Graf H, Boss A, König C, Pereira PL, Schick F. Biopsy needle tips with markers--MR compatible needles for high-precision needle tip positioning. Med Phys 2008; 35:2273-8. [PMID: 18649458 DOI: 10.1118/1.2919082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Needle tip visualization is of high importance in magnetic resonance imaging (MRI) guided interventional procedures, for example for taking biopsies from suspicious lesions in the liver or kidney. The exact position of the needle tip is often obscured by image artifacts arising from the magnetic properties of the needle. The authors investigated two special biopsy needle tip designs using diamagnetic coatings. For common interventional MR sequences, the needle tip can be identified in the MR image by several equidistant dark spots arranged along a straight line. A dotted instead of a solid line allows for an improved control of the movement of the needle, not only if the needle is tilted toward the imaging plane, but also if the needle leaves an empty canal with signal extinction, which cannot be distinguished from the needle material itself. With the proposed design the position of the needle tip can be estimated with a precision of approximately 1 mm using conventional FLASH, FISP, and TSE sequences, as used for interventional MR. Furthermore, the size of the biopsy probe can be estimated from the artifact. In using needles with a properly designed tip coating, taking biopsies under MR control is beginning to be greatly simplified. The approach to design artifacts using diamagnetic material in combination with paramagnetic material paves the way toward new instruments and implants, suitably tailored to the needs of the interventional radiologist.
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Affiliation(s)
- Bernd M Müller-Bierl
- Max-Planck Institute for Biological Cybernetics, Spemannstrasse 41, D-72076 Tübingen, Germany.
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MR-guided liver biopsy within a short, wide-bore 1.5 Tesla MR system. Eur Radiol 2008; 18:2865-73. [DOI: 10.1007/s00330-008-1088-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 03/16/2008] [Accepted: 04/27/2008] [Indexed: 10/21/2022]
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Zangos S, Eichler K, Thalhammer A, Schoepf JU, Costello P, Herzog C, Mack MG, Vogl TJ. MR-guided interventions of the prostate gland. MINIM INVASIV THER 2008; 16:222-9. [PMID: 17763096 DOI: 10.1080/13645700701520669] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In recent years MR imaging has played an increasingly important role in the diagnosis and treatment of prostate cancer. MR imaging of the prostate allows a clear delineation of the anatomic structures and prostate tumors when performing interventions such as biopsies, brachytherapy or thermal therapy of the prostate gland. MRI robotic assistance will improve the accuracy of the interventions. Due to the advantages of MR imaging MR-guided prostate interventions will play an increasing role in future.
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Affiliation(s)
- S Zangos
- Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Johann Wolfgang Goethe-University, Frankfurt/Main, Germany.
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Blumenfeld P, Hata N, DiMaio S, Zou K, Haker S, Fichtinger G, Tempany CMC. Transperineal prostate biopsy under magnetic resonance image guidance: a needle placement accuracy study. J Magn Reson Imaging 2007; 26:688-94. [PMID: 17729363 DOI: 10.1002/jmri.21067] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
PURPOSE To quantify needle placement accuracy of magnetic resonance image (MRI)-guided core needle biopsy of the prostate. MATERIALS AND METHODS A total of 10 biopsies were performed with 18-gauge (G) core biopsy needle via a percutaneous transperineal approach. Needle placement error was assessed by comparing the coordinates of preplanned targets with the needle tip measured from the intraprocedural coherent gradient echo images. The source of these errors was subsequently investigated by measuring displacement caused by needle deflection and needle susceptibility artifact shift in controlled phantom studies. Needle placement error due to misalignment of the needle template guide was also evaluated. RESULTS The mean and standard deviation (SD) of errors in targeted biopsies was 6.5 +/- 3.5 mm. Phantom experiments showed significant placement error due to needle deflection with a needle with an asymmetrically beveled tip (3.2-8.7 mm depending on tissue type) but significantly smaller error with a symmetrical bevel (0.6-1.1 mm). Needle susceptibility artifacts observed a shift of 1.6 +/- 0.4 mm from the true needle axis. Misalignment of the needle template guide contributed an error of 1.5 +/- 0.3 mm. CONCLUSION Needle placement error was clinically significant in MRI-guided biopsy for diagnosis of prostate cancer. Needle placement error due to needle deflection was the most significant cause of error, especially for needles with an asymmetrical bevel.
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Affiliation(s)
- Philip Blumenfeld
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Lee MJ, Kim S, Lee SA, Song HT, Huh YM, Kim DH, Han SH, Suh JS. Overcoming artifacts from metallic orthopedic implants at high-field-strength MR imaging and multi-detector CT. Radiographics 2007; 27:791-803. [PMID: 17495293 DOI: 10.1148/rg.273065087] [Citation(s) in RCA: 360] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
At magnetic resonance (MR) imaging and multidetector computed tomography (CT), artifacts arising from metallic orthopedic hardware are an obstacle to obtaining optimal images. Although various techniques for reducing such artifacts have been developed and corroborated by previous researchers, a new era of more powerful MR imaging and multidetector CT modalities has renewed the importance of a systematic consideration of methods for artifact reduction. Knowledge of the factors that contribute to artifacts, of related theories, and of artifact reduction techniques has become mandatory for radiologists. Factors that affect artifacts on MR images include the composition of the metallic hardware, the orientation of the hardware in relation to the direction of the main magnetic field, the strength of the magnetic field, the pulse sequence type, and other MR imaging parameters (mainly voxel size, which is determined by the field of view, image matrix, section thickness, and echo train length). At multidetector CT, the factors that affect artifacts include the composition of the hardware, orientation of the hardware, acquisition parameters (peak voltage, tube charge, collimation, and acquired section thickness), and reconstruction parameters (reconstructed section thickness, reconstruction algorithm used, and whether an extended CT scale was used). A comparison of images obtained with different hardware and different acquisition and reconstruction parameters facilitates an understanding of methods for reducing or overcoming artifacts related to metallic implants.
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Affiliation(s)
- Mi-Jung Lee
- Department of Diagnostic Radiology and Research Institute of Radiological Science and Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, 134 Sincheon-Dong Seodaemun-Gu, Seoul 120-752, Republic of Korea
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Müller-Bierl BM, Graf H, Pereira PL, Schick F. Numerical simulations of intra-voxel dephasing effects and signal voids in gradient echo MR imaging using different sub-grid sizes. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2006; 19:88-95. [PMID: 16779564 DOI: 10.1007/s10334-006-0031-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Accepted: 03/30/2006] [Indexed: 10/24/2022]
Abstract
Signal void artifacts in gradient echo imaging are caused by the intra-voxel dephasing of the spins. Intra-voxel dephasing can be estimated by computing the field distribution on a sub-grid inside each picture element, followed by integration of all magnetization components. The strategy of computing the artifacts based on the integration of the sub-voxel signal components is presented here for different sub-grids. The coarseness of the sub-grid is directly related to computational effort. The possibility to save memory space and computing time for the dipole model by computing the field only on a sub-grid is addressed in the presented article. It is investigated as to how far computational time and memory space can be reduced by using an appropriate sub-grid. Numerical results for a model of a partially diamagnetically coated needle shaft are compared to experimental findings. In the case of a pure titanium needle, it is shown as being sufficient to compute the field distribution on a sub-grid that is at least four times coarser in each direction than the grid used to discretize the object in the related MR image. Due to three nested loops over the 3D grid, the need for memory space and time is saved by a factor 64. Deviations between measurements and simulations for the broad side of the artifact (uncompensated) and for the small side of the artifact (compensated) were 15.5%, respectively, 19.1% for orientation parallel to the exterior field, and 22.7%, respectively, 23.1% for orientation perpendicular to the exterior field.
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Affiliation(s)
- Bernd M Müller-Bierl
- Department of Diagnostic Radiology, University Clinic Tuebingen, Hoppe-Seyler Strasse 3, 72076, Tuebingen, Germany.
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Zangos S, Vetter T, Huebner F, Tuwari M, Mayer F, Eichler K, Hansmann ML, Wetter A, Herzog C, Vogl TJ. MR-guided biopsies with a newly designed cordless coil in an open low-field system: Initial findings. Eur Radiol 2005; 16:2044-50. [PMID: 16344961 DOI: 10.1007/s00330-005-0069-1] [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] [Received: 08/15/2005] [Revised: 10/18/2005] [Accepted: 10/28/2005] [Indexed: 10/25/2022]
Abstract
The purpose of this study was to examine the feasibility and safety of MR-guided biopsies with a newly designed cordless coil in an open low-field magnetic resonance (MR) system. Eleven patients were biopsied using a low-field system (0.2 T, Magnetom Concerto, Siemens) by using the new cordless coil (Siemens). The biopsies were performed in different organ systems [liver (n = 7), abdomen (n = 1), shoulder (n = 1), pelvis (n = 1) and hip (n = 1)]. The procedures were guided using T1-weighted FLASH (fast low-angle shot) sequences. The lesions were biopsied using the coaxial technique through a 15-gauge puncture needle with a 16-gauge biopsy handy. Coil handling, image quality and complications were evaluated. Imaging quality and visualization of the lesions were optimal up to a penetration depth of 9 cm. In all cases the biopsy procedures were successfully performed with MR guidance without any complications. Pathological findings revealed seven cases of malignant tissue and four cases of non-malignant tissue. The use of the cordless coil allows improved patient access during the biopsy and an improved handling of the coil system. MR-guided biopsy using the novel cordless coil system can be performed safely and precisely with easy handling of the coil. This coil concept, however, is restricted to special indications.
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Affiliation(s)
- Stephan Zangos
- Institute for Diagnostic and Interventional Radiology, J. W. Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany.
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Zangos S, Eichler K, Wetter A, Lehnert T, Hammerstingl R, Diebold T, Reichel P, Herzog C, Hansmann ML, Mack MG, Vogl TJ. MR-guided biopsies of lesions in the retroperitoneal space: technique and results. Eur Radiol 2005; 16:307-12. [PMID: 16059677 DOI: 10.1007/s00330-005-2870-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2005] [Revised: 06/06/2005] [Accepted: 07/04/2005] [Indexed: 10/25/2022]
Abstract
The purpose of this study was to evaluate the safety and precision of MRI-guided biopsies of retroperitoneal space-occupying tumors in an open low-field system. In 30 patients with indistinct retroperitoneal tumors [paraaortic lesion (n=20), kidney (n=2), suprarenal gland (n=3) and pancreas (n=5)] MR-guided biopsies were performed using a low-field system (0.2 T, Magnetom Concerto, Siemens, Germany). For the monitoring of the biopsies T1-weighted FLASH sequences (TR/TE=160/5 ms; 90 degrees ) were used in all patients and modified FLASH sequences (TR/TE=160/13 ms; 90 degrees ) in ten patients. After positioning of the needle in the tumors 114 biopsy specimens were acquired in coaxial technique with 16-gauge cutting needles (Somatex, Germany). The biopsies were successfully performed in all patients without vascular or organ injuries. The visualization of the aortic blood flow with MRI facilitated the biopsy procedures of paraaortic lesions. The size of the lesions ranged from 1.6 to 7.5 cm. The median distance of the biopsy access path was 10.4 cm. Adequate specimens were obtained in 28 cases (93.3%) resulting in a correct histological classification of 27 lesions (90%). In conclusion, MR-guided biopsies of retroperitoneal lesions using an open low-field system can be performed safely and accurately and is an alternative to CT-guided biopsies.
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Affiliation(s)
- S Zangos
- Institute for Diagnostic and Interventional Radiology, J.W. Goethe University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany.
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Müller-Bierl B, Graf H, Steidle G, Schick F. Compensation of magnetic field distortions from paramagnetic instruments by added diamagnetic material: Measurements and numerical simulations. Med Phys 2004; 32:76-84. [PMID: 15719957 DOI: 10.1118/1.1828674] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
In minimally invasive procedures guided by magnetic resonance (MR) imaging instruments usually are made of titanium or titanium alloys (e.g., nitinol), because other more MR-compatible materials often cannot provide sufficient mechanical properties. Artifacts depending on susceptibility arise in MR images due to incorrect spatial encoding and intravoxel dephasing and thereby hamper the surgeon's view onto the region of interest. To overcome the artifact problem, compensation of the paramagnetic properties by diamagnetic coating or filling of the instruments has been proposed in the literature. We used a numerical modeling procedure to estimate the effect of compensation. Modeling of the perturbation of the static magnetic field close to the instruments reflects the underlying problem and is much faster and cost efficient than manufacturing prototypes and measuring artifact behavior of these prototypes in the MR scanner. A numerical model based on the decomposition of the susceptibility distribution in elementary dipoles was developed by us. The program code was written object oriented to allow for both maximum computational speed and minimum random access memory. We used System International units throughout the modeling for the magnetic field, allowing absolute quantification of the magnetic field disturbance. The field outside a simulated needlelike instrument, modeled by a paramagnetic cylinder (out of titan, chi =181.1) of length 8.0 mm and of diameter 1.0 mm, coated with a diamagnetic layer (out of bismuth, chi=-165.0) of thickness 0, 0.1, 0.2, 0.3, and 0.4 mm, was found to be best compensated if the cross-sectional area of the cylinder, multiplied by the absolute susceptibility value of the cylinder material, is equal to the cross-sectional area of the coating, multiplied by the absolute susceptibility value of the coating material. At the extremity of the coated cylinder an uncompensated field distortion was found to remain. We studied various tip shapes and geometries using our computational model: Suitable diamagnetic coating or filling of paramagnetic instruments clearly reduced tip artifacts and diminished the dependency of artifact size on orientation of the instrument with respect to B0 in the numerical studies. We verified the results of the simulations by measuring coated and uncoated titanium wires in a 1.5 T MR scanner.
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Affiliation(s)
- Bernd Müller-Bierl
- Diagnostics Radiology, University Hospital, Tuebingen, Bader-Wuertemberg 72076, Germany.
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Aubé C, Schmidt D, Brieger J, Schenk M, Helmberger T, Koenig CW, Schick F, Claussen CD, Pereira PL. Magnetic Resonance Imaging Characteristics of Six Radiofrequency Electrodes in a Phantom Study. J Vasc Interv Radiol 2004; 15:385-92. [PMID: 15064343 DOI: 10.1097/01.rvi.0000121408.46920.f1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
Abstract
PURPOSE To evaluate and compare visibility and artifacts in magnetic resonance (MR) compatible radiofrequency (RF) electrodes for MR-guided RF ablation. MATERIAL AND METHODS Six different MR compatible electrodes for RF ablation including two internally cooled single needles, one internally cooled cluster needle, two expandable needles and one perfused needle were tested in a phantom study at 0.2 Tesla and at 1.5 Tesla field strength. Fluoroscopic, T1- and T2-weighted fast spin echo (FSE) and gradient echo (GE) sequences, which are usually used for MR-guided interventions, were evaluated. Qualitative and quantitative evaluations were performed. Length, width, noise, tip artifacts, global artifacts and global visualization of the RF electrodes that showed all sequences at different angles. RESULTS Qualitative analysis showed that electrodes were well visualized at all angles and sequences and on both MR imagers. Quantitative analysis showed that artifact-induced widening of the shaft was increased in all electrodes by: a). use of fluoroscopic sequences, GE sequences, and fat saturation, b). increasing the angle between the needle and main magnetic field, and c). high field strength (1.5 T). Expandable needles produced fewer tip artifacts but broader signal voids along the shaft compared to nonexpandable needles. Cluster electrodes produced less widening than the other electrodes. CONCLUSION Visibility and artifacts in all six MR compatible RF electrodes are satisfactory and these electrodes could be used for MR-guided radiofrequency ablation procedures.
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Affiliation(s)
- Christophe Aubé
- Department of Radiology, University Hospital of Angers, Angers, France
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Müller-Bierl B, Graf H, Lauer U, Steidle G, Schick F. Numerical modeling of needle tip artifacts in MR gradient echo imaging. Med Phys 2004; 31:579-87. [PMID: 15070257 DOI: 10.1118/1.1640971] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Exact determination of needle tip position is obsolete for interventional procedures under control of magnetic resonance imaging (MRI). Exact needle tip navigation is complicated by the paramagnetism of microsurgical instruments: Local magnetic field inhomogeneities are induced resulting in position encoding artifacts and in signal voids in the surrounding of instruments and especially near their tips. The artifacts generated by the susceptibility of the material are not only dependent on the material properties themselves and on the applied MRI sequences and parameters, but also on the geometric shape of the instruments and on the orientation to the static magnetic field in the MR unit. A numerical model based on superposition of induced elementary dipole fields was developed for studying the field distortions near paramagnetic needle tips. The model was validated by comparison with experimental data using field mapping MRI techniques. Comparison between experimental data and numerical simulations revealed good correspondence for the induced field inhomogeneities. Further systematic numerical studies of the field distribution were performed for variable types of concentric and asymmetric tip shapes, for different ratios between tip length and needle diameter, and for different orientations of the needle axis in the external static magnetic field. Based on the computed local inhomogeneities of the magnetic field in the surroundings of the needle tips, signal voids in usual gradient echo images were simulated for a prediction of the artifacts. The practically relevant spatial relation between those artifacts and the hidden tip of the needle was calculated for the different tip shapes and orientations in the external field. As needle tip determination is crucial in interventional procedures, e.g., in taking biopsies, the present model can help to instruct the physician prior to surgical interventions in better estimating the needle tip position for different orientations and needle tip shapes as they appear in interventional procedures. As manufacturing prototypes with subsequent measurements of artifacts in MRI are a costly procedure the presented model may also help to optimize shapes of needle tips and of other parts of MR-compatible instruments and implants with low expense prior to production if some shape parameters can be chosen freely.
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Affiliation(s)
- Bernd Müller-Bierl
- Department of Diagnostic Radiology of the University Hospital Tübingen, Hoppe-Seyler Strasse 3, D-72076 Tübingen, Germany.
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Salomir R, de Senneville BD, Moonen CTW. A fast calculation method for magnetic field inhomogeneity due to an arbitrary distribution of bulk susceptibility. ACTA ACUST UNITED AC 2003. [DOI: 10.1002/cmr.b.10083] [Citation(s) in RCA: 280] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bos C, Viergever MA, Bakker CJG. On the artifact of a subvoxel susceptibility deviation in spoiled gradient-echo imaging. Magn Reson Med 2003; 50:400-4. [PMID: 12876717 DOI: 10.1002/mrm.10505] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In MRI, susceptibility-based negative contrast amplifies the effect of objects that are too small to be detected by water displacement or intrinsic contrast properties. In this work, a simplified description of the susceptibility artifact of a subvoxel object in spoiled gradient-echo imaging is presented that focuses on the elimination of signal in its vicinity: the dephased-volume. The size and position of the dephased-volume are investigated using 3D time-domain simulations and in vitro experiments in which scan parameters and object magnetic moment are systematically varied. Overall signal loss is found to be linearly related to a dephasing parameter that contains the susceptibility difference with tissue, object volume, and echo time (TE), and thus allows the magnetic moment of the object to be assessed. Gradient strength, in-plane resolution, fractional echo, and slice orientation have limited influence. For the settings used, the center of mass of the artifact was always within 0.5 mm of the object's in-plane position.
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Affiliation(s)
- Clemens Bos
- Department of Radiology, Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands.
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Lazebnik RS, Lancaster TL, Breen MS, Lewin JS, Wilson DL. Volume registration using needle paths and point landmarks for evaluation of interventional MRI treatments. IEEE TRANSACTIONS ON MEDICAL IMAGING 2003; 22:653-660. [PMID: 12846434 DOI: 10.1109/tmi.2003.812246] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We created a method for three-dimensional (3-D) registration of medical images (e.g., magnetic resonance imaging (MRI) or computed tomography) to images of physical tissue sections or to other medical images and evaluated its accuracy. Our method proved valuable for evaluation of animal model experiments on interventional-MRI guided thermal ablation and on a new localized drug delivery system. The method computes an optimum set of rigid body registration parameters by minimization of the Euclidean distances between automatically chosen correspondence points, along manually selected fiducial needle paths, and optional point landmarks, using the iterative closest point algorithm. For numerically simulated experiments, using two needle paths over a range of needle orientations, mean voxel displacement errors depended mostly on needle localization error when the angle between needles was at least 20 degrees. For parameters typical of our in vivo experiments, the mean voxel displacement error was < 0.35 mm. In addition, we determined that the distance objective function was a useful diagnostic for predicting registration quality. To evaluate the registration quality of physical specimens, we computed the misregistration for a needle not considered during the optimization procedure. We registered an ex vivo sheep brain MR volume with another MR volume and tissue section photographs, using various combinations of needle and point landmarks. Mean registration error was always < or = 0.54 mm for MR-to-MR registrations and < or = 0.52 mm for MR to tissue section registrations. We also applied the method to correlate MR volumes of radio-frequency induced thermal ablation lesions with actual tissue destruction. In this case, in vivo rabbit thigh volumes were registered to photographs of ex vivo tissue sections using two needle paths. Mean registration errors were between 0.7 and 1.36 mm over all rabbits, the largest error less than two MR voxel widths. We conclude that our method provides sufficient spatial correspondence to facilitate comparison of 3-D image data with data from gross pathology tissue sections and histology.
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Affiliation(s)
- Roee S Lazebnik
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106-7207 USA
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