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                                            Safety Information Article
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       Foreign Bodies and Screening 

 

Metallic Foreign Bodies and Screening

A patient or individual with a history of being injured by a metallic foreign body such as a bullet, shrapnel, or other metallic object should be thoroughly screened and evaluated prior to admission to the area of the MR system. This is particularly important because serious injury may occur as a result of movement or dislodgment of the metallic foreign body as it is attracted by the powerful static magnetic field. In addition, excessive heating may occur, although this tends to happen only if the object is made from conductive material and has an elongated shape or forms a loop of a certain diameter.

The relative risk of injury is dependent on the ferromagnetic properties of the foreign body, the geometry and dimensions of the object, the strength of the static magnetic field, and the strength of the spatial gradient magnetic field of the MR system. Additionally, the potential for injury is related to the amount of force with which the object is “fixed” or retained within the tissue (i.e. counter-force or retention force from scarring or encapsulation may prevent migration of the metal) and whether or not it is positioned in or adjacent to a sensitive site of the body such as vital neural, vascular, or soft tissue structure.

The use of plain film radiography is the technique of choice recommended to detect metallic foreign bodies for individuals and patients prior to admission to the MR environment. This includes screening for the presence of metallic orbital foreign bodies (see Metallic Orbital Foreign Bodies and Screening). The sensitivity of plain film radiography is considered to be sufficient to identify any metal object with a mass large enough to present a hazard to an individual or patient in the MR environment.

Recent information from a report by Karacozoff and Shellock (2013) suggests that a special ferromagnetic detection system (Ferroguard Screener, Metrasens) may provide an additional means of guiding the decision making process regarding management of patients with metallic foreign bodies insofar as this device was successfully utilized to identify a ferromagnetic, armor-piercing bullet.

REFERENCES

Boutin RD, et al. Injuries associated with MR imaging: Survey of safety records and methods used to screen patients for metallic foreign bodies before imaging. Am J Roentgenol 1994;162:189.

Dempsey MF, Condon B, Hadley DM. Investigation of the factors responsible for burns during MRI. J Magn Reson Imag 2001;13:627-631.

Elster AD, et al. Patient screening prior to MR imaging: A practical approach synthesized from protocols at 15 U.S. medical centers. Am J Roentgenol 1994;162:195.

Eshed I, et al. Is magnetic resonance imaging safe for patients with retained metal fragments from combat and terrorist attacks? Acta Radiol 2010;51:170-4.

Karacozoff AM, Shellock FG. Armor-piercing bullet: 3-Tesla MRI findings and identification by a ferromagnetic detection system. Military Medicine 2013;178:e380-5.

International Commission on Non-Ionizing Radiation Protection (ICNIRP) statement, medical magnetic resonance procedures: Protection of patients. Health Physics 2004;87:197-216.

Jarvik JG, Ramsey JG. Radiographic screening for orbital foreign bodies prior to MR imaging: Is it worth it? Am J Neuroradiol 2000;1:245.

Mani, RL. In search of an effective screening system for intraocular metallic foreign bodies prior to MR - An important issue of patient safety. Am J Neuroradiol 1988;9:1032.

Murphy KJ, Burnberg JA. Orbital plain film as a prerequisite for MR imaging: Is a known history of injury sufficient screening criteria? Am J Roentgenol 1996;167:1053.

Otto PM, et al. Screening test for detection of metallic foreign objects in the orbit before magnetic resonance imaging. Invest Radiol 1992;27:308-311.

Seidenwurm DJ, et al. Cost utility analysis of radiographic screening for an orbital foreign body before MR imaging. Am J Neuroradiol 2000;21:426.

Shellock FG. Magnetic Resonance Procedures: Health Effects and Safety. CRC Press, LLC, Boca Raton, FL, 2001.

Shellock FG, Crues JV. MR procedures: Biologic effects, safety, and patient care. Radiology 2004;232:635-652.

Shellock FG, Crues JV, Editors. MRI Bioeffects, Safety, and Patient Management. Biomedical Research Publishing Group, Los Angeles, CA, 2014.

Shellock FG, Kanal E. SMRI Safety Committee. Policies, guidelines, and recommendations for MR imaging safety and patient management. J Magn Reson Imag 1991;1:97-101.

Williams S, et al. Ferrous intraocular foreign bodies and magnetic resonance imaging. Am J Ophthalmology 1998;105:398.

Zhang Y, et al. Tiny ferromagnetic intraocular foreign bodies detected by magnetic resonance imaging: A report of two cases. J Magn Reson Imag 2009;29:704-7.



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