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Bohner L, Dirksen D, Hanisch M, Sesma N, Kleinheinz J, Meier N. Artifacts in magnetic resonance imaging of the head and neck: Unwanted effects caused by implant-supported restorations fabricated with different alloys. J Prosthet Dent 2023:S0022-3913(23)00554-1. [PMID: 37739882 DOI: 10.1016/j.prosdent.2023.08.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 08/20/2023] [Accepted: 08/21/2023] [Indexed: 09/24/2023]
Abstract
STATEMENT OF PROBLEM Implant-supported restorations may cause artifacts in magnetic resonance imaging (MRI) of the head and neck area. However, the effect of different alloys remains unclear. PURPOSE The purpose of this in vitro study was to assess artifacts in head and neck MRI caused by implant-supported restorations with different alloys. MATERIAL AND METHODS Three dry mandibles were prepared to receive bilateral dental implants at the second premolar and second molar sites. Different alloy combinations were evaluated: titanium implants+cobalt chromium restorations; titanium-zirconium implants+cobalt chromium restorations; and zirconia implants+ceramic restorations. Specimens were imaged by using a 3-Tesla magnetic resonance scanner system (Achieva 3.0T TX; Philips GmbH) with a turbo-spin-echo sequence. Scan protocols were adjusted to optimize metal artifact reduction and shorten scan time. Artifact volumes were assessed and statistically analyzed by using the Kruskal-Wallis and Spearman tests (α=.05). RESULTS A statistically significant difference was found among artifact volume caused by different materials (P=.002). The presence of titanium alloy was correlated with the artifact volume (r=-.87). Artifacts were greater for titanium and fewer for titanium-zirconium alloys, whereas zirconia implants found only minimal artifacts. CONCLUSIONS The dimension of artifacts produced by implant-supported restorations varied according to the material.
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Affiliation(s)
- Lauren Bohner
- Research Associate, Department of Cranio-Maxillofacial Surgery, University Hospital Muenster, Muenster, Germany.
| | - Dieter Dirksen
- Professor, Department of Prosthodontics and Biomaterials, University Hospital Muenster, Muenster, Germany
| | - Marcel Hanisch
- Research Associate, Department of Cranio-Maxillofacial Surgery, University Hospital Muenster, Muenster, Germany
| | - Newton Sesma
- Professor, Department of Prosthodontics, School of Dentistry, University of São Paulo (USP), São Paulo, Brazil
| | - Johannes Kleinheinz
- Professor, Department of Cranio-Maxillofacial Surgery, University Hospital Muenster, Muenster, Germany
| | - Norbert Meier
- Research Associate, Department of Radiology, University Hospital Muenster, Muenster, Germany
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2
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Abramson ZR, Nagaraj UD, Lai LM, Liu CCY, Schroeder JW, Khanna PC, Chuang NA, Strauss S, Gomez G, Clarke R, Singh S, Choudhri AF, Whitehead MT. Imaging of pediatric head and neck tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee/ASPNR White Paper. Pediatr Blood Cancer 2023; 70 Suppl 4:e30151. [PMID: 36546312 PMCID: PMC10644272 DOI: 10.1002/pbc.30151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 11/24/2022] [Indexed: 12/24/2022]
Affiliation(s)
- Zachary R Abramson
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Usha D Nagaraj
- Department of Radiology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio, USA
| | - Lillian M Lai
- Department of Radiology, University of Iowa Hospitals and Clinics and Stead Family Children's Hospital, Iowa City, Iowa, USA
| | - Christopher Cheng-Yu Liu
- Department of Otolaryngology, Pediatric Otolaryngology Division, UT Southwestern Medical Center and Children's Health Dallas, Dallas, Texas, USA
| | - Jason W Schroeder
- Department of Radiology, Children's National Hospital, Washington, District of Columbia, USA
| | - Paritosh C Khanna
- Department of Radiology, Rady Children's Hospital, University of California, San Diego, California, USA
| | - Nathaniel A Chuang
- Department of Radiology, Rady Children's Hospital, University of California, San Diego, California, USA
| | - Sara Strauss
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
| | - Gabriel Gomez
- University of Southern California, Keck School of Medicine, Department of Otolaryngology-Head and Neck Surgery, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - Rebekah Clarke
- Department of Radiology, University of Texas Southwestern Medical Center and Children's Health Dallas, Dallas, Texas, USA
| | - Sumit Singh
- Department of Radiology, University of Texas Southwestern Medical Center and Children's Health Dallas, Dallas, Texas, USA
| | - Asim F Choudhri
- Le Bonheur Neuroscience Institute, Le Bonheur Children's Hospital, Departments of Radiology, Ophthalmology, and Neurosurgery, University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee, USA
| | - Matthew T Whitehead
- Department of Radiology, Children's National Hospital, Washington, District of Columbia, USA
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3
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Johannsen KM, de Carvalho E Silva Fuglsig JM, Hansen B, Wenzel A, Spin-Neto R. Magnetic resonance imaging artefacts caused by orthodontic appliances and/or implant-supported prosthesis: a systematic review. Oral Radiol 2023; 39:394-407. [PMID: 36178613 DOI: 10.1007/s11282-022-00652-9] [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: 06/23/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022]
Abstract
OBJECTIVES Dental materials, including orthodontic appliances and implants, are commonly mentioned as a possible source of artefacts in magnetic resonance imaging (MRI). The aim of the present study was to undertake a systematic review of the relevant literature on MR image artefacts due to dental materials, limited to orthodontic appliances and implant-supported dental prosthesis, on both technical and diagnostic levels. METHODS The MEDLINE (PubMed) bibliographic database was searched up to September 2020. The search was limited to studies published in English, using the search string: (MRI or magnetic resonance) and (artefact or artifact) and (dental or ortho or implant or restoration or restorative). The studies were assessed independently by three reviewers, focusing on the following parameters: MRI sequences, tested materials, assessed parameters, efficacy level and outcome. RESULTS The search strategy yielded 31 studies, which were included in this systematic review. These studies showed that metallic dental materials, commonly present in orthodontic appliances and implant-supported dental prosthesis led to diverse types/severities of artefacts in MR images. Fifteen studies were in vivo, based on human subjects. The studies differed substantially in terms of tested materials, assessed parameters, and outcome measurements. CONCLUSIONS Metallic dental materials cause artefacts of diverse types and severities in MR images of the head and neck region. However, the diagnostic relevance of the investigated artefacts for the diverse MRI applications is yet to be studied.
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Affiliation(s)
- Katrine Mølgaard Johannsen
- Department of Dentistry and Oral Health, Oral Radiology, Aarhus University, Vennelyst Boulevard 9, 8000, Aarhus, Denmark.
| | | | - Brian Hansen
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Ann Wenzel
- Department of Dentistry and Oral Health, Oral Radiology, Aarhus University, Vennelyst Boulevard 9, 8000, Aarhus, Denmark
| | - Rubens Spin-Neto
- Department of Dentistry and Oral Health, Oral Radiology, Aarhus University, Vennelyst Boulevard 9, 8000, Aarhus, Denmark
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4
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SEMAC + VAT for Suppression of Artifacts Induced by Dental-Implant-Supported Restorations in Magnetic Resonance Imaging. J Clin Med 2023; 12:jcm12031117. [PMID: 36769765 PMCID: PMC9917855 DOI: 10.3390/jcm12031117] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/29/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
The purpose of this study was to assess the feasibility of SEMAC + VAT to reduce artifacts induced by dental implant-supported restorations, such as its impact on the image quality. Dental-implant supported restorations were installed in a dry mandible. Magnetic resonance scans were acquired on a 3-Tesla MRI system. Artifact suppression (SEMAC + VAT) was applied with different intensity modes (weak, moderate, strong). Artifacts assessment was performed by measuring the mandible volume increase in MRI images prior (reference dataset) and after installation of dental implant-supported prosthesis. Image quality was assessed by two examiners using a five-point scale. Inter-examiner concordance and correlation analysis was performed with Cronbach's alpha and Spearman's test with a significance level at p = 0.05. Mandible volume increased by 60.23% when no artifact suppression method was used. By applying SEMAC + VAT, the volume increase ranged from 17.13% (strong mode) to 32.77% (weak mode). Visualization of mandibular bone was positively correlated with SEMAC intensity degree. SEMAC + VAT reduced MRI artifacts caused by dental-implant supported restorations. A stronger suppression mode improved visualization of mandibular bone in detriment of the scanning time.
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5
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Abstract
Attenuation correction has been one of the main methodological challenges in the integrated positron emission tomography and magnetic resonance imaging (PET/MRI) field. As standard transmission or computed tomography approaches are not available in integrated PET/MRI scanners, MR-based attenuation correction approaches had to be developed. Aspects that have to be considered for implementing accurate methods include the need to account for attenuation in bone tissue, normal and pathological lung and the MR hardware present in the PET field-of-view, to reduce the impact of subject motion, to minimize truncation and susceptibility artifacts, and to address issues related to the data acquisition and processing both on the PET and MRI sides. The standard MR-based attenuation correction techniques implemented by the PET/MRI equipment manufacturers and their impact on clinical and research PET data interpretation and quantification are first discussed. Next, the more advanced methods, including the latest generation deep learning-based approaches that have been proposed for further minimizing the attenuation correction related bias are described. Finally, a future perspective focused on the needed developments in the field is given.
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Affiliation(s)
- Ciprian Catana
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States of America
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6
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Abstract
We aimed to assess the usefulness of slice-encoding metal artifact correction (SEMAC) for the evaluation of spinal metallic implants and peripheral soft tissue lesions at 3T magnetic resonance.Twenty-seven patients with spinal metal implants underwent both SEMAC and high bandwidth (HiBW) based sequences scanning for reduction artifacts. The area size and maximum longitude of artifacts, the peri-prosthetic soft tissue, and metal visualization were assessed by 2 independent doctors, as well as the lesions signs were reviewed by 2 senior readers. A paired 2-tailed t-test and McNemar test were used for statistical analysis.The size of artifacts on SEMAC images decreased by 37% and 24%, and the scores are higher than that on HiBW images. T1 weighted (T1W)-SEMAC acquired the highest score in metal prosthesis visualization, while short tau inversion recovery SEMAC showed more signs of lesions than clinical HiBW group.SEMAC effectively reduces the metal artifacts and is useful for assessing soft tissue lesions.
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Affiliation(s)
- Chun Xin
- School of Medical Imaging, Jiangsu Vocational College of Medicine, Yancheng
| | - Houdong Liu
- School of Medical Imaging, Jiangsu Vocational College of Medicine, Yancheng
| | - Shihong Li
- Department of Radiology, Huadong Hospital, Fudan University, Shanghai, China
| | - Guangwu Lin
- Department of Radiology, Huadong Hospital, Fudan University, Shanghai, China
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7
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Evaluation of magnetic resonance imaging for diagnostic purposes in operative dentistry—a systematic review. Clin Oral Investig 2019; 24:547-557. [DOI: 10.1007/s00784-019-03103-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 09/26/2019] [Indexed: 10/25/2022]
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8
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Kajima Y, Takaichi A, Tsutsumi Y, Hanawa T, Wakabayashi N, Kawasaki A. Influence of magnetic susceptibility and volume on MRI artifacts produced by low magnetic susceptibility Zr-14Nb alloy and dental alloys. Dent Mater J 2019; 39:256-261. [PMID: 31723091 DOI: 10.4012/dmj.2018-426] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The artifact volume generated in magnetic resonance (MR) images was quantitatively evaluated to investigate how artifact behavior correlates to the magnetic susceptibility and volume of an implanted metal device. For this, a new low-magnetic-susceptibility Zr-14Nb alloy was compared with two conventional dental alloys, Ti-6Al-7Nb alloy and Co-Cr-Mo alloy, using spherical specimens of each alloy prepared with four different diameters. Then, MR images were recorded under fast spin echo and gradient echo conditions, from which the artifact volume was measured. The artifact volume decreased with the magnetic susceptibility, volume, and mass of the specimens, and significant linear correlations were observed. The artifact volume can be estimated by the equations presented here; nevertheless, further studies are necessary to interpret the influence of some important factors (e.g., imaging conditions, shape, and orientation) to predict the artifact volume more precisely.
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Affiliation(s)
- Yuka Kajima
- Department of Materials Processing, Graduate School of Engineering, Tohoku University
| | - Atsushi Takaichi
- Removable Partial Prosthodontics, Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University
| | - Yusuke Tsutsumi
- Department of Metallic Biomaterials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University
| | - Takao Hanawa
- Department of Metallic Biomaterials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University
| | - Noriyuki Wakabayashi
- Removable Partial Prosthodontics, Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University
| | - Akira Kawasaki
- Department of Materials Processing, Graduate School of Engineering, Tohoku University
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9
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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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10
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Hilgenfeld T, Prager M, Schwindling FS, Nittka M, Rammelsberg P, Bendszus M, Heiland S, Juerchott A. MSVAT-SPACE-STIR and SEMAC-STIR for Reduction of Metallic Artifacts in 3T Head and Neck MRI. AJNR Am J Neuroradiol 2018; 39:1322-1329. [PMID: 29794233 DOI: 10.3174/ajnr.a5678] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 03/30/2018] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The incidence of metallic dental restorations and implants is increasing, and head and neck MR imaging is becoming challenging regarding artifacts. Our aim was to evaluate whether multiple-slab acquisition with view angle tilting gradient based on a sampling perfection with application-optimized contrasts by using different flip angle evolution (MSVAT-SPACE)-STIR and slice-encoding for metal artifact correction (SEMAC)-STIR are beneficial regarding artifact suppression compared with the SPACE-STIR and TSE-STIR in vitro and in vivo. MATERIALS AND METHODS At 3T, 3D artifacts of 2 dental implants, supporting different single crowns, were evaluated. Image quality was evaluated quantitatively (normalized signal-to-noise ratio) and qualitatively (2 reads by 2 blinded radiologists). Feasibility was tested in vivo in 5 volunteers and 5 patients, respectively. RESULTS Maximum achievable resolution and the normalized signal-to-noise ratio of MSVAT-SPACE-STIR were higher compared with SEMAC-STIR. Performance in terms of artifact correction was dependent on the material composition. For highly paramagnetic materials, SEMAC-STIR was superior to MSVAT-SPACE-STIR (27.8% smaller artifact volume) and TSE-STIR (93.2% less slice distortion). However, MSVAT-SPACE-STIR reduced the artifact size compared with SPACE-STIR by 71.5%. For low-paramagnetic materials, MSVAT-SPACE-STIR performed as well as SEMAC-STIR. Furthermore, MSVAT-SPACE-STIR decreased artifact volume by 69.5% compared with SPACE-STIR. The image quality of all sequences did not differ systematically. In vivo results were comparable with in vitro results. CONCLUSIONS Regarding susceptibility artifacts and acquisition time, MSVAT-SPACE-STIR might be advantageous over SPACE-STIR for high-resolution and isotropic head and neck imaging. Only for materials with high-susceptibility differences to soft tissue, the use of SEMAC-STIR might be beneficial. Within limited acquisition times, SEMAC-STIR cannot exploit its full advantage over TSE-STIR regarding artifact suppression.
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Affiliation(s)
- T Hilgenfeld
- From the Department of Neuroradiology, (T.H., M.P., M.B., S.H., A.J.)
| | - M Prager
- From the Department of Neuroradiology, (T.H., M.P., M.B., S.H., A.J.).,Section of Experimental Radiology (M.P., S.H.), University of Heidelberg, Heidelberg, Germany
| | - F S Schwindling
- Department of Prosthodontics (F.S.S., P.R.), Heidelberg University Hospital, Heidelberg, Germany
| | - M Nittka
- Siemens Healthcare (M.N.), Erlangen, Germany
| | - P Rammelsberg
- Department of Prosthodontics (F.S.S., P.R.), Heidelberg University Hospital, Heidelberg, Germany
| | - M Bendszus
- From the Department of Neuroradiology, (T.H., M.P., M.B., S.H., A.J.)
| | - S Heiland
- From the Department of Neuroradiology, (T.H., M.P., M.B., S.H., A.J.).,Section of Experimental Radiology (M.P., S.H.), University of Heidelberg, Heidelberg, Germany
| | - A Juerchott
- From the Department of Neuroradiology, (T.H., M.P., M.B., S.H., A.J.)
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11
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Hilgenfeld T, Prager M, Schwindling FS, Jende JME, Rammelsberg P, Bendszus M, Heiland S, Juerchott A. Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences. J Vis Exp 2018:57394. [PMID: 29863680 PMCID: PMC6101223 DOI: 10.3791/57394] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
As the number of magnetic resonance imaging (MRI) scanners and patients with medical implants is constantly growing, radiologists increasingly encounter metallic implant-related artifacts in MRI, resulting in reduced image quality. Therefore, the MRI suitability of implants in terms of artifact volume, as well as the development of pulse sequences to reduce image artifacts, are becoming more and more important. Here, we present a comprehensive protocol which allows for a standardized evaluation of the artifact volume of implants on MRI. Furthermore, this protocol can be used to analyze the vulnerability of different pulse sequences to artifacts. The proposed protocol can be applied to T1- and T2-weighted images with or without fat-suppression and all passive implants. Furthermore, the procedure enables the separate and three-dimensional identification of signal loss and pile-up artifacts. As previous investigations differed greatly in evaluation methods, the comparability of their results was limited. Thus, standardized measurements of MRI artifact volumes are necessary to provide better comparability. This may improve the development of the MRI suitability of implants and better pulse sequences to finally improve patient care.
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Affiliation(s)
- Tim Hilgenfeld
- Department of Neuroradiology, Heidelberg University Hospital
| | - Marcel Prager
- Department of Neuroradiology, Heidelberg University Hospital
| | | | | | | | - Martin Bendszus
- Department of Neuroradiology, Heidelberg University Hospital
| | - Sabine Heiland
- Department of Neuroradiology, Heidelberg University Hospital
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12
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Abstract
Combined PET/MR imaging scanners capable of acquiring simultaneously the complementary information provided by the 2 imaging modalities are now available for human use. After addressing the hardware challenges for integrating the 2 imaging modalities, most of the efforts in the field have focused on developing MR-based attenuation correction methods for neurologic and whole-body applications, implementing approaches for improving one modality by using the data provided by the other and exploring research and clinical applications that could benefit from the synergistic use of the multimodal data.
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Affiliation(s)
- Ciprian Catana
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Building 149, 13th Street, Room 2.301, Charlestown, MA 02129, USA.
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13
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Hilgenfeld T, Prager M, Heil A, Schwindling FS, Nittka M, Grodzki D, Rammelsberg P, Bendszus M, Heiland S. PETRA, MSVAT-SPACE and SEMAC sequences for metal artefact reduction in dental MR imaging. Eur Radiol 2017; 27:5104-5112. [DOI: 10.1007/s00330-017-4901-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 03/14/2017] [Accepted: 05/16/2017] [Indexed: 01/13/2023]
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14
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Hua J, Miao X, Agarwal S, Bettegowda C, Quiñones-Hinojosa A, Laterra J, Van Zijl PCM, Pekar JJ, Pillai JJ. Language Mapping Using T2-Prepared BOLD Functional MRI in the Presence of Large Susceptibility Artifacts-Initial Results in Patients With Brain Tumor and Epilepsy. ACTA ACUST UNITED AC 2017; 3:105-113. [PMID: 28804779 PMCID: PMC5552052 DOI: 10.18383/j.tom.2017.00006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
At present, presurgical functional mapping is the most prevalent clinical application of functional magnetic resonance imaging (fMRI). Signal dropouts and distortions caused by susceptibility effects in the current standard echo planar imaging (EPI)-based fMRI images are well-known problems and pose a major hurdle for the application of fMRI in several brain regions, many of which are related to language mapping in presurgical planning. Such artifacts are particularly problematic in patients with previous surgical resection cavities, craniotomy hardware, hemorrhage, and vascular malformation. A recently developed T2-prepared (T2prep) fMRI approach showed negligible distortion and dropouts in the entire brain even in the presence of large susceptibility effects. Here, we present initial results comparing T2prep- and multiband EPI-fMRI scans for presurgical language mapping using a sentence completion task in patients with brain tumor and epilepsy. In all patients scanned, T2prep-fMRI showed minimal image artifacts (distortion and dropout) and greater functional sensitivity than EPI-fMRI around the lesions containing blood products and in air-filled cavities. This enhanced sensitivity in T2prep-fMRI was also evidenced by the fact that functional activation during the sentence completion task was detected with T2prep-fMRI but not with EPI-fMRI in the affected areas with the same statistical threshold, whereas cerebrovascular reactivity during a breath-hold task was preserved in these same regions, implying intact neurovascular coupling in these patients. Although further investigations are required to validate these findings with invasive methods such as direct cortical stimulation mapping as the gold standard, this approach provides an alternative method for performing fMRI in brain regions with large susceptibility effects.
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Affiliation(s)
- Jun Hua
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland.,Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Xinyuan Miao
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland.,Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Shruti Agarwal
- Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chetan Bettegowda
- Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | | | - John Laterra
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Peter C M Van Zijl
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland.,Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - James J Pekar
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland.,Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jay J Pillai
- Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
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15
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Probst M, Richter V, Weitz J, Kirschke JS, Ganter C, Troeltzsch M, Nittka M, Cornelius CP, Zimmer C, Probst FA. Magnetic resonance imaging of the inferior alveolar nerve with special regard to metal artifact reduction. J Craniomaxillofac Surg 2017; 45:558-569. [DOI: 10.1016/j.jcms.2017.01.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 12/08/2016] [Accepted: 01/09/2017] [Indexed: 11/30/2022] Open
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16
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Jungmann PM, Agten CA, Pfirrmann CW, Sutter R. Advances in MRI around metal. J Magn Reson Imaging 2017; 46:972-991. [PMID: 28342291 DOI: 10.1002/jmri.25708] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 03/03/2017] [Indexed: 01/02/2023] Open
Abstract
The prevalence of orthopedic metal implants is continuously rising in the aging society. Particularly the number of joint replacements is increasing. Although satisfying long-term results are encountered, patients may suffer from complaints or complications during follow-up, and often undergo magnetic resonance imaging (MRI). Yet metal implants cause severe artifacts on MRI, resulting in signal-loss, signal-pileup, geometric distortion, and failure of fat suppression. In order to allow for adequate treatment decisions, metal artifact reduction sequences (MARS) are essential for proper radiological evaluation of postoperative findings in these patients. During recent years, developments of musculoskeletal imaging have addressed this particular technical challenge of postoperative MRI around metal. Besides implant material composition, configuration and location, selection of appropriate MRI hardware, sequences, and parameters influence artifact genesis and reduction. Application of dedicated metal artifact reduction techniques including high bandwidth optimization, view angle tilting (VAT), and the multispectral imaging techniques multiacquisition variable-resonance image combination (MAVRIC) and slice-encoding for metal artifact correction (SEMAC) may significantly reduce metal-induced artifacts, although at the expense of signal-to-noise ratio and/or acquisition time. Adding advanced image acquisition techniques such as parallel imaging, partial Fourier transformation, and advanced reconstruction techniques such as compressed sensing further improves MARS imaging in a clinically feasible scan time. This review focuses on current clinically applicable MARS techniques. Understanding of the main principles and techniques including their limitations allows a considerate application of these techniques in clinical practice. Essential orthopedic metal implants and postoperative MR findings around metal are presented and highlighted with clinical examples. LEVEL OF EVIDENCE 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:972-991.
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Affiliation(s)
- Pia M Jungmann
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Faculty of Medicine, University of Zurich, Zurich, Switzerland.,Department of Radiology, Technical University of Munich, Munich, Germany
| | - Christoph A Agten
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Faculty of Medicine, University of Zurich, Zurich, Switzerland
| | - Christian W Pfirrmann
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Department of Radiology, Technical University of Munich, Munich, Germany
| | - Reto Sutter
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Department of Radiology, Technical University of Munich, Munich, Germany
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17
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Zhou DB, Wang SG, Wang SP, Ai HJ, Xu J. MRI compatibility of several early transition metal based alloys and its influencing factors. J Biomed Mater Res B Appl Biomater 2017; 106:377-385. [PMID: 28160410 DOI: 10.1002/jbm.b.33832] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 07/15/2016] [Accepted: 10/02/2016] [Indexed: 11/06/2022]
Abstract
Magnetic resonance imaging (MRI) compatibility of three early transition metal (ETM) based alloys was assessed in vitro with agarose gel as a phantom, including Zr-20Nb, near-equiatomic (TiZrNbTa)90 Mo10 and Nb-60Ta-2Zr, together with pure tantalum and L605 Co-Cr alloy for comparison. The artifact extent in the MR image was quantitatively characterized according to the maximum area of 2D images and the total volume in reconstructed 3D images with a series of slices under acquisition by fast spin echo (FSE) sequence and gradient echo (GRE) sequence. It was indicated that the artifacts extent of L605 Co-Cr alloy with a higher magnetic susceptibility (χv ) was approximately 3-fold greater than that of the ETM-based alloys with χv in the range of 160-250 ppm. In the ETM group, the MRI compatibility of the materials can be ranked in a sequence of Zr-20Nb, pure tantalum, (TiZrNbTa)90 Mo10 and Nb-60Ta-2Zr. In addition, using a rabbit cadaver with the implanted tube specimens as a model for ex vivo assessment, it was confirmed that the artifact severity of Nb-60Ta-2Zr alloy is significantly reduced in comparison with the L605 alloy. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 377-385, 2018.
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Affiliation(s)
- Da-Bo Zhou
- School of Stomatology, China Medical University, Shenyang, 110002, China
| | - Shao-Gang Wang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Shao-Ping Wang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Hong-Jun Ai
- School of Stomatology, China Medical University, Shenyang, 110002, China
| | - Jian Xu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China
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18
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Experience with magnetic resonance imaging of human subjects with passive implants and tattoos at 7 T: a retrospective study. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2015; 28:577-90. [DOI: 10.1007/s10334-015-0499-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 07/25/2015] [Accepted: 08/19/2015] [Indexed: 10/23/2022]
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Zachriat C, Asbach P, Blankenstein KI, Peroz I, Blankenstein FH. MRI with intraoral orthodontic appliance-a comparative in vitro and in vivo study of image artefacts at 1.5 T. Dentomaxillofac Radiol 2015; 44:20140416. [PMID: 25734243 DOI: 10.1259/dmfr.20140416] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES We investigated artefacts caused from orthodontic appliances at 1.5-T MRI of the head and neck region and whether the image quality can be improved utilizing the artefact-minimizing sequence WARP. METHODS In vitro tests were performed by phantom measurements of different orthodontic devices applying different types of MR sequences [echoplanar imaging (EPI), turbo spin echo (TSE) and TSE-WARP, gradient echo (GRE)]. Two independent readers determined after calibration the level of artefacts. Subsequently, the interobserver agreement was calculated. The measurement of artefacts was based on the American Society for Testing Materials Standard F 2119-07. For in vivo imaging, one test person was scanned with an inserted multibracket appliance. The level of artefacts for 27 target regions was evaluated. RESULTS In vitro: ceramic brackets and ferromagnetic steel brackets produced artefact radii up to 1.12 and 7.40 cm, respectively. WARP reduced these artefacts by an average of 32.7%. The Bland-Altman-Plot indicated that maximum measurement differences of 3 mm have to be expected with two calibrated observers. In vivo: the EPI sequence for brain imaging was not analysable. The TSE sequence of the brain did not demonstrate artefacts except for the nasal cavity. Conversely, the TSE sequence of the cervical spine revealed severe artefacts in the midface region. The GRE sequence appeared to be more susceptible to artefacts than did the TSE sequence. CONCLUSIONS In vitro measurements allow an estimation of the in vivo artefact size. Orthodontic appliances may often remain intraorally when performing MRI. WARP showed a more significant effect in vitro than in vivo.
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Affiliation(s)
- C Zachriat
- 1 Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - P Asbach
- 2 Department of Radiology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
| | - K I Blankenstein
- 3 Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - I Peroz
- 1 Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - F H Blankenstein
- 1 Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Berlin, Germany
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Bachschmidt TJ, Köhler M, Nistler J, Geppert C, Jakob PM, Nittka M. Polarized multichannel transmit MRI to reduce shading near metal implants. Magn Reson Med 2015; 75:217-26. [PMID: 25684374 DOI: 10.1002/mrm.25621] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 12/23/2014] [Accepted: 12/30/2014] [Indexed: 12/26/2022]
Abstract
PURPOSE To investigate the benefit of a two-channel transmit system on shading close to total hip replacements and other elongated metal structures in parallel to the magnet bore. METHODS An analytical model comprising a water cylinder and a metal rod is introduced to describe the B1 effects close to elongated metal structures and it is verified. The dependence of the optimal polarization, which induces minimum shading, on the position of the metal is analyzed. Furthermore, the optimal polarization for two patients is determined both on the basis of the model and experimentally and its benefit compared with circular polarization is investigated. RESULTS The cylindrical model approximates the modification of the B1 field due to the metal well, and the optimal polarization strongly depends on the position of the rod. In vivo, shading can be ameliorated by the use of the optimal polarization; for total hip replacements with shafts of titanium, this polarization can be determined on the basis of both the analytical model and the experimental data. CONCLUSION Parallel transmission offers the possibility of a substantial reduction of shading close to long metal structures in parallel to the magnet bore.
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Affiliation(s)
- Theresa J Bachschmidt
- Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany.,Magnetic Resonance, Siemens AG, Erlangen, Germany
| | | | | | | | - Peter M Jakob
- Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany
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21
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Gunzinger JM, Delso G, Boss A, Porto M, Davison H, von Schulthess GK, Huellner M, Stolzmann P, Veit-Haibach P, Burger IA. Metal artifact reduction in patients with dental implants using multispectral three-dimensional data acquisition for hybrid PET/MRI. EJNMMI Phys 2014; 1:102. [PMID: 26501460 PMCID: PMC4545455 DOI: 10.1186/s40658-014-0102-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 11/06/2014] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) shows high potential for patients with oropharyngeal cancer. Dental implants can cause substantial artifacts in the oral cavity impairing diagnostic accuracy. Therefore, we evaluated new MRI sequences with multi-acquisition variable-resonance image combination (MAVRIC SL) in comparison to conventional high-bandwidth techniques and in a second step showed the effect of artifact size on MRI-based attenuation correction (AC) with a simulation study. METHODS Twenty-five patients with dental implants prospectively underwent a trimodality PET/CT/MRI examination after informed consent was obtained under the approval of the local ethics committee. A conventional 3D gradient-echo sequence (LAVA-Flex) commonly used for MRI-based AC of PET (acquisition time of 14 s), a T1w fast spin-echo sequence with high bandwidth (acquisition time of 3.2 min), as well as MAVRIC SL sequence without and with increased phase acceleration (MAVRIC, acquisition time of 6 min; MAVRIC-fast, acquisition time of 3.5 min) were applied. The absolute and relative reduction of the signal void artifact was calculated for each implant and tested for statistical significance using the Wilcoxon signed-rank test. The effect of artifact size on PET AC was simulated in one case with a large tumor in the oral cavity. The relative difference of the maximum standardized uptake value (SUVmax) in the tumor was calculated for increasing artifact sizes centered over the second molar. RESULTS The absolute reduction of signal void from LAVA-Flex sequences to the T1-weighted fast spin-echo (FSE) sequences was 416 mm(2) (range 4 to 2,010 mm(2)) to MAVRIC 481 mm(2) (range 12 to 2,288 mm(2)) and to MAVRIC-fast 486 mm(2) (range 39 to 2,209 mm(2)). The relative reduction in signal void was significantly improved for both MAVRIC and MAVRIC-fast compared to T1 FSE (-75%/-78% vs. -62%, p < 0.001 for both). The relative error for SUVmax was negligible for artifacts of 0.5-cm diameter (-0.1%), but substantial for artifacts of 5.2-cm diameter (-33%). CONCLUSIONS MAVRIC-fast could become useful for artifact reduction in PET/MR for patients with dental implants. This might improve diagnostic accuracy especially for patients with tumors in the oropharynx and substantially improve accuracy of PET quantification.
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Affiliation(s)
- Jeanne M Gunzinger
- Department of Medical Radiology, Division of Nuclear Medicine, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland.
| | - Gaspar Delso
- Global MR Applications and Workflow, GE Healthcare, CH-8048, Zurich, Switzerland.
| | - Andreas Boss
- Department of Medical Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland.
| | - Miguel Porto
- Department of Medical Radiology, Division of Nuclear Medicine, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland.
| | - Helen Davison
- Department of Medical Radiology, Division of Nuclear Medicine, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland.
| | - Gustav K von Schulthess
- Department of Medical Radiology, Division of Nuclear Medicine, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland.
| | - Martin Huellner
- Department of Medical Radiology, Division of Nuclear Medicine, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland. .,Department of Medical Radiology, Institute of Neuroradiology, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland.
| | - Paul Stolzmann
- Department of Medical Radiology, Division of Nuclear Medicine, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland. .,Department of Medical Radiology, Institute of Neuroradiology, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland.
| | - Patrick Veit-Haibach
- Department of Medical Radiology, Division of Nuclear Medicine, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland. .,Department of Medical Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland.
| | - Irene A Burger
- Department of Medical Radiology, Division of Nuclear Medicine, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland. .,Department of Medical Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Ramistr. 100, CH-8091, Zurich, Switzerland.
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22
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Bachschmidt TJ, Sutter R, Jakob PM, Pfirrmann CWA, Nittka M. Knee implant imaging at 3 Tesla using high-bandwidth radiofrequency pulses. J Magn Reson Imaging 2014; 41:1570-80. [PMID: 25155582 DOI: 10.1002/jmri.24729] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 08/04/2014] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND To investigate the impact of high-bandwidth radiofrequency (RF) pulses used in turbo spin echo (TSE) sequences or combined with slice encoding for metal artifact correction (SEMAC) on artifact reduction at 3 Tesla in the knee in the presence of metal. METHODS Local transmit/receive coils feature increased maximum B1 amplitude, reduced SAR exposition and thus enable the application of high-bandwidth RF pulses. Susceptibility-induced through-plane distortion scales inversely with the RF bandwidth and the view angle, hence blurring, increases for higher RF bandwidths, when SEMAC is used. These effects were assessed for a phantom containing a total knee arthroplasty. TSE and SEMAC sequences with conventional and high RF bandwidths and different contrasts were tested on eight patients with different types of implants. To realize scan times of 7 to 9 min, SEMAC was always applied with eight slice-encoding steps and distortion was rated by two radiologists. RESULTS A local transmit/receive knee coil enables the use of an RF bandwidth of 4 kHz compared with 850 Hz in conventional sequences. Phantom scans confirm the relation of RF bandwidth and through-plane distortion, which can be reduced up to 79%, and demonstrate the increased blurring for high-bandwidth RF pulses. In average, artifacts in this RF mode are rated hardly visible for patients with joint arthroplasties, when eight SEMAC slice-encoding steps are applied, and for patients with titanium fixtures, when TSE is used. CONCLUSION The application of high-bandwidth RF pulses by local transmit coils substantially reduces through-plane distortion artifacts at 3 Tesla.
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Affiliation(s)
- Theresa J Bachschmidt
- Department of Experimental Physics 5, University of Wuerzburg, Wuerzburg, Germany.,Magnetic Resonance, Siemens AG, Erlangen, Germany
| | - Reto Sutter
- Department of Radiology, Orthopedic University Hospital Balgrist, Zurich, Switzerland.,University of Zurich, Faculty of Medicine, Zurich, Switzerland
| | - Peter M Jakob
- Department of Experimental Physics 5, University of Wuerzburg, Wuerzburg, Germany
| | - Christian W A Pfirrmann
- Department of Radiology, Orthopedic University Hospital Balgrist, Zurich, Switzerland.,University of Zurich, Faculty of Medicine, Zurich, Switzerland
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23
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Friedrich B, Wostrack M, Ringel F, Ryang YM, Förschler A, Waldt S, Zimmer C, Nittka M, Preibisch C. Novel Metal Artifact Reduction Techniques with Use of Slice-Encoding Metal Artifact Correction and View-Angle Tilting MR Imaging for Improved Visualization of Brain Tissue near Intracranial Aneurysm Clips. Clin Neuroradiol 2014; 26:31-7. [PMID: 25081235 DOI: 10.1007/s00062-014-0324-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/17/2014] [Indexed: 11/24/2022]
Abstract
PURPOSE The MR image quality after intracranial aneurysm clipping is often impaired because of artifacts induced by metal implants. The purpose of the present study was to evaluate the benefit of a new WARP sequence with slice-encoding metal artifact correction (SEMAC) and view-angle tilting (VAT) MR imaging as novel artifact reduction techniques. MATERIALS AND METHODS A new WARP TSE (a work-in-progress software package provided by Siemens Healthcare) sequence was implemented for cranial applications based on a turbo spin echo (TSE) sequence. T1- and T2-weighted images with standard and WARP TSE sequences were acquired from 6 patients with 11 clipping sites, and the images were compared based on artifact size and general image quality. RESULTS T2- and T1-weighted WARP TSE sequences resulted in a highly significant reduction of metal artifacts compared with standard sequences (T2w- WARP TSE: 89.8 ± 1.4 %; T1w- WARP TSE: 84.9 ± 2.9 %; p < 0.001) without a substantial loss of image quality. CONCLUSION The use of a new WARP TSE sequence after aneurysm clipping is highly beneficial for increasing the diagnostic MR image quality due to a striking reduction of metal artifacts.
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Affiliation(s)
- B Friedrich
- Department of Neuroradiology, Klinikum rechts der Isar, Ismaningerstr. 22, 81675, Munich, Germany. .,Department of diagnostic and interventional Radiology, University Hospital Leipzig, Leipzig, Germany.
| | - M Wostrack
- Department of Neurosurgery, Klinikum rechts der Isar, Munich, Germany
| | - F Ringel
- Department of Neurosurgery, Klinikum rechts der Isar, Munich, Germany
| | - Y-M Ryang
- Department of Neurosurgery, Klinikum rechts der Isar, Munich, Germany
| | - A Förschler
- Department of Neuroradiology, Klinikum rechts der Isar, Ismaningerstr. 22, 81675, Munich, Germany
| | - S Waldt
- Department of Radiology, Klinikum rechts der Isar, Munich, Germany
| | - C Zimmer
- Department of Neuroradiology, Klinikum rechts der Isar, Ismaningerstr. 22, 81675, Munich, Germany
| | - M Nittka
- Siemens Healthcare, Erlangen, Germany
| | - C Preibisch
- Department of Neuroradiology, Klinikum rechts der Isar, Ismaningerstr. 22, 81675, Munich, Germany
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Steinmetz C, Mader I, Arndt S, Aschendorff A, Laszig R, Hassepass F. MRI artefacts after Bonebridge implantation. Eur Arch Otorhinolaryngol 2014; 271:2079-82. [DOI: 10.1007/s00405-014-3001-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 03/03/2014] [Indexed: 11/30/2022]
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25
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Sveinsson B, Worters PW, Gold GE, Hargreaves BA. Hexagonal undersampling for faster MRI near metallic implants. Magn Reson Med 2014; 73:662-8. [PMID: 24549782 DOI: 10.1002/mrm.25132] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 12/20/2013] [Accepted: 12/21/2013] [Indexed: 12/22/2022]
Abstract
PURPOSE Slice encoding for metal artifact correction acquires a three-dimensional image of each excited slice with view-angle tilting to reduce slice and readout direction artifacts respectively, but requires additional imaging time. The purpose of this study was to provide a technique for faster imaging around metallic implants by undersampling k-space. METHODS Assuming that areas of slice distortion are localized, hexagonal sampling can reduce imaging time by 50% compared with conventional scans. This work demonstrates this technique by comparisons of fully sampled images with undersampled images, either from simulations from fully acquired data or from data actually undersampled during acquisition, in patients and phantoms. Hexagonal sampling is also shown to be compatible with parallel imaging and partial Fourier acquisitions. Image quality was evaluated using a structural similarity (SSIM) index. RESULTS Images acquired with hexagonal undersampling had no visible difference in artifact suppression from fully sampled images. The SSIM index indicated high similarity to fully sampled images in all cases. CONCLUSION The study demonstrates the ability to reduce scan time by undersampling without compromising image quality.
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Affiliation(s)
- Bragi Sveinsson
- Department of Radiology, Stanford University, Stanford, California, USA; Department of Electrical Engineering, Stanford University, Stanford, California, USA
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