Screening for intra-orbital metallic foreign bodies prior to MRI: Review of the evidence

Magnetic resonance imaging of patients with a metallic Intra-Orbital Foreign Body (IOFB) may be hazardous. Much controversy exists with regard to the optimum initial screening protocol to be undertaken which will ensure patients with metallic IOFBs do not enter the MR controlled area. Once a patient has been screened as 'at risk', further variations in practice exist with regard to optimum imaging modality and radiographic technique to rule out the FB. This is due to a paucity of empirical research which is diverse in approach and conclusion. MR radiographers are developing their role and, as advanced practitioners, will find themselves increasingly involved in decision-making with regard to patient safety. Although it may feel a comfortable option to request a radiograph on all patients who pose a dilemma, MR radiographers need to be able to defend such a course of action through a thorough understanding of the financial and dose implications as discussed in the literature. This review will highlight some of the arguments both for and against screening patients for metallic IOFB and consider the radiographic screening options for 'at risk' patients.