Is magnetic resonance imaging safe for patients with retained metal fragments from combat and terrorist attacks?

Background: Increasing numbers of military confrontations and terrorist attacks have led to increasing reports of retained metal fragments among patients referred for magnetic resonance imaging (MRI). The potential hazard of retained metal fragments for patients undergoing MRI has been studied among patients with retained metal fragments from domestic violence but not from combat and terrorist attacks. Purpose: To retrospectively evaluate the safety of MRI in patients with subcutaneous warfare-metal fragments. Material and Methods: 10,322 consecutive metal screening forms of patients scheduled for 1.5 Tesla (T) MR examination were retrospectively reviewed. All patients reported to have retained metal fragments were contacted by telephone and asked to describe the event in which they were exposed to the fragments and for any adverse sequelae or sensations during and after MRI. Their radiographs were evaluated for the number and size of the fragments. The data were analyzed for correlations between these factors. Results: Seven of the 24 patients who reported retained metal fragments were excluded, since there was no validating evidence of their presence. Fragments in the remaining 17 patients (18 MRI examinations) were inflicted by military or terrorist attacks that occurred 239 years prior to the MRI. The fragment size ranged between 1 and 10 mm. One patient reported a superficial migration of a 10-mm fragment after MRI. No other adverse reactions were reported. Conclusion: Conducting 1.5T MRI examinations is safe in patients with retained metal fragments from combat and terrorist attacks not in the vicinity of vital organs. However, caution is advised.