Sebastian Eggert1,2, Rahel A Kubik-Huch2, Martin Lory3, John M Froehlich4, Dominic Gascho1, Michael J Thali1, Stephan A Bolliger5. 1. Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Winterthurerstrasse 190/52, Zurich, 8057, Switzerland. 2. Department of Radiology, Kantonsspital Baden AG, Baden, Switzerland. 3. Forensic Institute Zurich, Zurich, Switzerland. 4. Federal Institute of Technology, Pharmaceutical Sciences, Zurich, Switzerland. 5. Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Winterthurerstrasse 190/52, Zurich, 8057, Switzerland. stephan.bolliger@irm.uzh.ch.
Abstract
PURPOSE: Ferromagnetic bullets can move in air or gelatin in magnetic resonance (MR) units. According to our experience, ferromagnetic bullets do not always present consistent movement. We examined factors affecting ferromagnetic projectile movement in a 1.5T and a 3T MR unit, focusing in this study on the steel-jacketed Swiss ordnance ammunition 7.5 mm GP11 Suisse. METHODS: Five 7.5 mm GP11 Suisse bullets were embedded horizontally and vertically in 10 % ordnance gelatin phantoms. Before and after exposing the bullets to 1.5T (Siemens) and 3T (Philips) MR units each bullet's position was documented by a CT scan. In a second phase, the magnetic polarization of the bullets in relation to the MR units was measured by a dry magnetic portable compass (Suunto). RESULTS: Our results showed that the displacement of the bullets increased when subjected to a stronger magnetic field (max. Movement 1.5T: 24.4 mm vs. 3T: 101.5 mm) and that the position, i.e. orientation of the bullet toward the gantry, strongly influenced its mobility (horizontally embedded projectiles showed poor movement, vertically placed ones strong movement). One of the bullets presented a 180° rotation in the 3T MR unit. Magnetization and changing of the polarization of these ferromagnetic bullets is possible when subjected to MR units. CONCLUSION: In conclusion, the location of a bullet, and its orientation toward the gantry must be taken into account when assessing the risk of performing an MR examination on a gunshot victim in clinical and in forensic cases.
PURPOSE: Ferromagnetic bullets can move in air or gelatin in magnetic resonance (MR) units. According to our experience, ferromagnetic bullets do not always present consistent movement. We examined factors affecting ferromagnetic projectile movement in a 1.5T and a 3T MR unit, focusing in this study on the steel-jacketed Swiss ordnance ammunition 7.5 mm GP11 Suisse. METHODS: Five 7.5 mm GP11 Suisse bullets were embedded horizontally and vertically in 10 % ordnance gelatin phantoms. Before and after exposing the bullets to 1.5T (Siemens) and 3T (Philips) MR units each bullet's position was documented by a CT scan. In a second phase, the magnetic polarization of the bullets in relation to the MR units was measured by a dry magnetic portable compass (Suunto). RESULTS: Our results showed that the displacement of the bullets increased when subjected to a stronger magnetic field (max. Movement 1.5T: 24.4 mm vs. 3T: 101.5 mm) and that the position, i.e. orientation of the bullet toward the gantry, strongly influenced its mobility (horizontally embedded projectiles showed poor movement, vertically placed ones strong movement). One of the bullets presented a 180° rotation in the 3T MR unit. Magnetization and changing of the polarization of these ferromagnetic bullets is possible when subjected to MR units. CONCLUSION: In conclusion, the location of a bullet, and its orientation toward the gantry must be taken into account when assessing the risk of performing an MR examination on a gunshot victim in clinical and in forensic cases.
Authors: Russell D Dedini; Alexandra M Karacozoff; Frank G Shellock; Duan Xu; R Trigg McClellan; Murat Pekmezci Journal: Spine J Date: 2013-04-03 Impact factor: 4.166
Authors: Michael J Thali; Beat P Kneubuehl; Peter Vock; Gabriel v Allmen; Richard Dirnhofer Journal: Am J Forensic Med Pathol Date: 2002-09 Impact factor: 0.921
Authors: Sebastian Eggert; Rahel A Kubik-Huch; Markus Klarhöfer; Alexander Peters; Stephan A Bolliger; Michael J Thali; Suzanne Anderson; Johannes M Froehlich Journal: Eur Radiol Date: 2015-02-25 Impact factor: 5.315
Authors: Stephan A Bolliger; Michael J Thali; Dominic Gascho; Sebastian A Poschmann; Sebastian Eggert Journal: Int J Legal Med Date: 2017-03-16 Impact factor: 2.686