Safety in magnetic resonance units: an update

The number of anaesthetists who are involved in magnetic resonance (MR) units is increasing. Magnetic resonance systems are becoming more powerful and interventional procedures are now possible. This paper updates information relating to safety terminology, occupational exposure, reactions to gadolinium-based contrast agents and the risk of nephrogenic systemic fibrosis. Magnetic resonance examinations of patients with pacemakers are still generally contra-indicated but have been carried out in specialist centres under strictly controlled conditions. As availability of MR increases, so the education of anaesthetists, who are occasionally required to provide a service, must be considered. Anaesthesia in MR units was first described in the 1980s. Guidelines on the provision of anaesthetic services in MR units were published by the Association of Anaesthetists of Great Britain and Ireland (AAGBI) in 2002 [1]. Since then, the number of hospitals with MR units, and hence the number of patients requiring anaesthesia for MR, has increased. While the issues relating to setting up anaesthetic services in MR have not changed, there have been a number of developments that warrant this update: 1 Safety terminology and guidelines have changed. 2 MR systems utilise higher magnetic-field strengths and more open designs are available. 3 Interventional and intra-operative MR are now routine in some centres. 4 Mobile MR scanners are increasingly used to reduce waiting lists. 5 Although still generally contra-indicated, some patients with pacemakers have been scanned under strictly controlled conditions in specialist centres. 6 ‘MR safe’ medical implants are now being produced. 7 New equipment is now available for use in MR. 8 Out-of-hours availability of MR investigations has increased. 9 Reports of allergic reactions to MR contrast media have increased. 10 Gadolinium based contrast agents (Gd-CAs) are associated with a varying degree of risk of nephrogenic systemic fibrosis in patients with impaired renal function.