title: Can postmortem MRI be used to assess trajectories in gunshot victims?
abstract: OBJECTIVE
  Multi-detector computed tomography (MDCT) has proven to be of value for the reconstruction of trajectories of projectiles and the assessment of the injuries in deceased gunshot victim. For the depiction of soft tissue injury, MRI is superior to MDCT and MRI may be of value to assess trajectories. In a clinical setting, there are guidelines for the application of MRI in patients with projectiles or projectile fragments and with precautions MRI is safe for these patients. However, this has not been studied for the postmortem application of MRI from a forensic point of view.
  
  
  METHODS
  To assess the behaviour of projectiles, two ferromagnetic and one non-ferromagnetic projectile were exposed to the magnetic field of a 1.5- and 3-T MRI. Projectiles were placed in six phantoms with the characteristics of human muscle tissue, with and without a simulated trajectory in the gel. Before and after exposure to the magnetic field, the gelatine phantoms were imaged with MDCT to assess the position of the projectiles.
  
  
  RESULTS
  The ferromagnetic projectiles rotate to a position where their long axis is parallel to the z-axis of the magnetic field and five out of the six projectiles moved through, either through the simulated trajectory or through a new trajectory. This was observed in both the 1.5- and 3-T systems.
  
  
  CONCLUSIONS
  Ferromagnetic projectiles can rotate and migrate in a gelatine phantom. It is very likely that these projectiles will also migrate in a human body in a MRI system. Therefore, from a forensic point of view, postmortem MR will make a reconstruction of the trajectories in the body and of the reconstruction of the incident as a whole less reliable.
authors.affiliation: Dutch Police, Region Limburg, PO Box 1230, 6201 BE, Maastricht, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Luijten
authors.affiliation: Department of Radiology, Maastricht University Medical Center, PO. Box 5800, 6202 AZ, Maastricht, The Netherlands.
authors.forename: I I H
authors.initials: II
authors.lastname: Haest
authors.affiliation: Dutch Police, Region Limburg, PO Box 1230, 6201 BE, Maastricht, The Netherlands.
authors.forename: R A T
authors.initials: RA
authors.lastname: van Kan
authors.affiliation: Dutch Police, Region Limburg, PO Box 1230, 6201 BE, Maastricht, The Netherlands.
authors.forename: W
authors.initials: W
authors.lastname: van Lohuizen
authors.affiliation: Department of Radiology, Maastricht University Medical Center, PO. Box 5800, 6202 AZ, Maastricht, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Kroll
authors.affiliation: Department of Radiology, Maastricht University Medical Center, PO. Box 5800, 6202 AZ, Maastricht, The Netherlands.
authors.forename: R S
authors.initials: RS
authors.lastname: Schnerr
authors.affiliation: Netherlands Forensic Institute, PO Box 24044, 2490 AA, The Hague, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Hermsen
authors.affiliation: Department of Radiology, Maastricht University Medical Center, PO. Box 5800, 6202 AZ, Maastricht, The Netherlands. paul.hofman@mumc.nl.
authors.forename: P A M
authors.initials: PA
authors.lastname: Hofman
mesh_terms: D044709:Forensic Ballistics / Q000379:methods*; D005780:Gelatin; D006801:Humans; D008279:Magnetic Resonance Imaging; D008954:Models, Biological; D061330:Multidetector Computed Tomography; D019047:Phantoms, Imaging; D014948:Wounds, Gunshot / Q000000981:diagnostic imaging*
chemical_list: D005780:Gelatin
keywords: Forensic radiology; Gunshot; MR imaging; Postmortem imaging; Projectile; Safety