Ferromagnetic detection system ensures patient safety before MRI

A ferromagnetic detection system could further patient safety prior to MRI, according to a study published in the October issue of the Journal of American Roentology.

Frank G. Shellock, MD, of the University of Southern California and Institute for Magnetic Resonance Safety, Education, and Research, and colleagues conducted a study of ferromagnetic detection systems in order to evaluate their ability to assess ferromagnetic implants and other objects encountered in patients referred for MRI procedures.

Researchers used a “pillar-type” ferromagnetic detection system on 67 different implants and objects. A voluntary subject with each test item approached the detection system and rotated four times in front of it. The subject then withdrew from the system while alarms monitored and recorded each scenario.

Overall, the ferromagnetic detection system found 58 true-positives, four true-negatives, zero false-positives and five false-negatives. The several false-negatives were objects of low magnetic content that would pose no real threat to a patient’s health and safety. The system’s sensitivity was found to be 92 percent while its specificity was 100 percent. Shellock and colleagues also discovered that it was particularly useful in screening patients with electronically activated implants that incorporate pulse generators.

“The results indicated that, besides being used to identify external ferromagnetic objects, this ferromagnetic detection system may be a useful tool to screen patients referred for MRI examinations who have implanted or embedded objects,” wrote Shellock and colleagues. “Thus, this information represents a potentially important means of preventing serious injuries in the MRI environment.”

The study’s researchers advise that ferromagnetic detection systems be supplementary to the pre-established screening process for MRI patients.