SAFETY OF MR-IMAGING IN PATIENTS WHO HAVE RETAINED METALLIC MATERIALSAFTER CARDIAC-SURGERY

OBJECTIVE. Epicardial pacing wires retained in patients who undergo ca rdiac surgery are thought to be a relative contraindication to MR imag ing. However, to our knowledge no published evidence supports this bel ief. Because other metallic materials retained after cardiac surgery m ight represent a hazard to patients who undergo MR imaging, we sought to determine the safety of such imaging.SUBJECTS AND METHODS. We exami ned 200 patients who underwent MR imaging at 1 or 1.5 T after cardiac surgery, Eighty-one were examined with ECG monitoring, The presence of temporary epicardial pacing wires, prosthetic valves, and other metal materials was confirmed by chest radiography. RESULTS. Of the 200 pat ients reviewed, all had postoperative metallic material visible on che st radiographs. Temporary epicardial pacing wire, cut short at the ski n, was seen in 51 patients. Of the 81 patients examined with ECG monit oring, we found that MR imaging produced no changes from baseline ECG rhythms. None of the 200 patients reported symptoms suggesting arrhyth mia or other cardiac dysfunction during MR imaging, CONCLUSION. MR ima ging can be performed safely in patients who have undergone cardiac su rgery and have retained metallic material, including valve replacement s and temporary epicardial pacing wires cut short at the skin. MR imag ing of patients with pacemakers was not evaluated, and we recommend th at pacemakers remain a contraindication to MR imaging.