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Local heating of metallic objects from switching magnetic gradients in MRI
Author(s): John Stroud; Karl Stupic; Tucker Walsh; Zbigniew Celinski; Janusz H. Hankiewicz
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Paper Abstract

Previously it has been shown that heat induced in metallic objects due to fast switching magnetic gradients can pose a possible danger not only for patients undergoing MRI procedures, but also to medical staff present. In this study, we investigate magnetic flux changes and the effects of local heating in metallic elements by eddy currents due to fast switching magnetic gradients at several specific positions with respect to the isocenter of the gradient coils. Experiments were performed in a 3 T preclinical scanner with a 30 cm bore. To probe the induced electro motive force (EMF), which results in induced eddy currents, small pickup coils were used at various locations in the scanner. To investigate heating, metallic cylinders (12.5 mm diameter, 12.6 mm height) were prepared with a pinhole to accommodate miniature fiber optic temperature sensors. A gradient echo axial imaging sequence was applied for 4 minutes after achieving thermal equilibrium with the magnet. Three different materials were used in this study: copper, aluminum, and Ti-6AL-4V, a titanium alloy commonly used in orthopedic implants. In these experiments, a direct dependence on position and gradient strength on the induced EMF was observed. As expected, the increase of temperature depended directly on distance and material composition. Heating can be a danger during imaging of patients with conductive implants that are placed away from the isocenter. Thus, our findings are vital to patient safety and comfort during MRI procedures.

Paper Details

Date Published: 15 March 2019
PDF: 12 pages
Proc. SPIE 10954, Medical Imaging 2019: Imaging Informatics for Healthcare, Research, and Applications, 109540O (15 March 2019); doi: 10.1117/12.2512903
Show Author Affiliations
John Stroud, Univ. of Colorado at Colorado Springs (United States)
Karl Stupic, National Institute of Standards and Technology (United States)
Tucker Walsh, Univ. of Colorado at Colorado Springs (United States)
Zbigniew Celinski, Univ. of Colorado at Colorado Springs (United States)
Janusz H. Hankiewicz, Univ. of Colorado at Colorado Springs (United States)


Published in SPIE Proceedings Vol. 10954:
Medical Imaging 2019: Imaging Informatics for Healthcare, Research, and Applications
Po-Hao Chen; Peter R. Bak, Editor(s)

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