| Torque measurements of the ossicular chain: implication on the MRI safety of the hearing implant Vibrant Soundbridge. | |
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MedLine Citation:
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PMID: 20142797 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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HYPOTHESIS: Is the human ossicular chain stabile enough to withstand the torque of a Vibrant Soundbridge middle ear hearing implant in the magnetic field of a 1.5 T magnetic resonance imaging (MRI) system? BACKGROUND: The Vibrant Soundbridge is a semi-implantable hearing device in which a tiny electromechanical transducer, called floating mass transducer (FMT), is clipped to the ossicular chain within the middle ear. The FMT contains a permanent magnet, which can generate a torque when exposed to a static magnetic field of MRI systems. Since the transducer is routinely attached to the long process of the incus, this torque could affect or even disrupt the ossicular chain. This study investigates the likelihood of a middle ear injury by an FMT in an MRI system. METHODS: Torque measurements were performed on 10 unpreserved human temporal bones. A brass fork was attached to the long process of the incus via a posterior tympanotomy, and a defined torque was applied by a calibrated torque meter. The torque was increased stepwise until an injury of the middle ear was observed. RESULTS: The mean torque at which the middle ear was injured was 4.3 mN.m +/- 1.7 mN.m. The lowest value measured was 1.5 mN.m, and the highest was 6.5 mN.m. CONCLUSION: Even the lowest torque measured is more than 1.5 times higher than the "worst-case" torque affecting the FMT during a 1.5 T MRI examination. The torque on an FMT crimped to the long process of the incus should therefore not harm the human middle ear. |
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Authors:
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Marco Otto Jesacher; Jan Kiefer; Clemens Zierhofer; Claudius Fauser |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology Volume: 31 ISSN: 1537-4505 ISO Abbreviation: Otol. Neurotol. Publication Date: 2010 Jun |
Date Detail:
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Created Date: 2010-05-26 Completed Date: 2010-10-25 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100961504 Medline TA: Otol Neurotol Country: United States |
Other Details:
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Languages: eng Pagination: 676-80 Citation Subset: IM |
Affiliation:
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Department of Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria. marco.jesacher@uibk.ac.at |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Ear Ossicles* Equipment Safety* Humans Magnetic Resonance Imaging* Models, Anatomic Ossicular Prosthesis* Prosthesis Design Temporal Bone Torque |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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