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MAY 2013 • Vol. 2, Issue 2 |
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ISMRM/SMRT Joint Forum: Panel Addresses MRI Safety Concerns |
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History The Joint Forum is collaboration between the ISMRM and the SMRT to provide a clinically-oriented educational forum on a topic of interest to members of both organisations, particularly the clinicians who attend the ISMRM meeting. Topic selection and planning is a joint effort by representatives of the ISMRM and the SMRT, and must include an equal or majority number of technologists/radiographers speaking during the program. Glenn Cahoon, B.App.Sc., Dip.Ed., MApp.Sc. and Derek Jones, Ph.D. co-chaired the 2013 forum entitled The Safe and Ethical Scanning of Patients and Research Subjects. MRI Safety has long been recognised as a significant issue in the daily use of magnetic resonance technology. However, the terminology and application of this knowledge in the field is less clearly defined. This inter-disciplinary course was aimed to update technologists and clinicians on the latest developments in the field of MRI safety, and potential methods to improve understanding and implementation of safety standards in the future. A novel approach was applied to the Joint Forum this year by inviting a panel of leading experts to discuss current knowledge, trends, and controversies in MRI safety. The faculty consisted of a cross-section of MR technologists from the clinical, research, and educational disciplines, a radiologist, a physicist, and a physiologist responsible for device testing in MRI. Presenters Frank Shellock, Ph.D. is a physiologist with over 25 years experience conducting laboratory and clinical investigations in the field of MRI. He is the author of the Reference manual for Magnetic Resonance Safety, Implants, and Devices, and manages MRIsafety.com a website dedicated to providing current information on MR safety, bio-effects, and patient management. His presentation focused on the latest information regarding the MRI safety of electronically activated, or “Active”, implants. Traditionally, active implants were generally contraindicated for patients undergoing MRI due to a variety of possible risks including those related to magnetic field interactions, excessive heating, induced currents, and electromagnetic interference. As a result of comprehensive testing to define acceptable conditions, combined with many manufacturers redesigning their products, there are now several devices with approved MRI conditional labeling. Dr. Shellock gave an overview of the latest devices, their MR safety status, and conditions for their use in an MRI environment. William (Bill) Faulkner has been teaching MRI to technologists and physicians for over 18 years. Bill has also authored MR registry review books and is a co-author and contributing author for several books and publications. His presentation focused on MR conditional pacemakers. Bill has been working closely with device manufacturers to educate MRI practitioners in how to safely image patients with these implants. In particular, how to correctly identify them, and the conditions required to scan patients with them. Positive identification is vital as many of these devices have multiple parts, each with their own specific safety conditions. Bill also emphasized the importance of using the correct terminology when referring to safety of patients and implants. He suggested implants or devices should only be labeled “MR Unsafe” or “MR Conditional.” MR Conditional labeling means that the object has been demonstrated to pose no known hazards in a specified MR environment under specified conditions of use. Because these conditions vary with the implant/device, blanket policies to scan certain “types” of devices are very dangerous and should not be implemented. Because these are labeled as “MR Conditional,” one must positively identify the device, and know the conditions of use, to adequately ensure the safety of the patient during the MRI exam. Gregory Brown has been studying MRI, and helping others to de-mystify it since 1985. He is a Fellow of the SMRT, has received the Crues-Kressel award for his educational efforts, and was awarded Honorary membership at the 2013 Meeting in Salt Lake City. Greg’s talk focused on Magnetic Spatial Gradients (MSG). This is an area of MRI safety that has been difficult for many to conceptualize, and has lead to much confusion in the MR community. MR Conditional labeling of devices often mentions a maximum spatial gradient under which their devices may be exposed to in an MRI environment. MRI equipment manufactures also state maximum spatial gradients in their specification manuals. Greg explained the source of these spatial gradients, and how to interpret the information from the varying manufacturers. He also showed how to read the gradient field maps to determine the position and strength of the field gradients, and how to determine whether a particular device would be safe in your particular facility. Dr. Donald McRobbie is Director of the Radiological Sciences Unit at Imperial College London. He is co-author of the MRI textbook ‘From Picture to Proton’ and is a recent co-leader of the European Commission for the study of occupational exposure to time varying magnetic fields. His presentation focused on the current research into the setting of limits for exposure to magnetic fields, and how the proposed limits were likely to affect clinical practice. Dr. McRobbie discussed the historical basis for this research, and how recent changes to guidelines have been made to accommodate magnetic resonance imaging. Dr. Emanuel Kanal is Director of MR services at the University of Pittsburgh Medical Center. Dr. Kanal is a prolific contributor to the field of MR education and is recognized as the pre-eminent physician authority on MR safety issues. Dr. Kanal is a Founding Member of numerous national and international professional societies, and serves as a consultant to the FDA on MR safety issues. Anne Marie Sawyer is Manager of the MR Whole body research systems at the Richard M Lucas Center for Imaging, Stanford University School of Medicine. Anne has been involved in MRI and MR education since 1985, and is a Fellow of the SMRT. She is the editor of the SMRT home studies and winner of numerous prestigious awards, including the Crues-Kressel Award (2001), and Honorary Member (2006) in recognition of her contributions to MR education. Anne also participates on the Technology Advisory Board for the IMRSER (Institute for Magnetic Resonance Safety, Education, and Research). The IMRSER is an independent organization devoted to promote awareness of MR safety issues through education and research. Dr. Emanuel Kanal and Anne-Marie Sawyer discussed perhaps the most significant recent development in MRI safety. In the past year we have seen the emergence of formal definitions and acceptance for a Fixed Parameter Option (FPO) mode of operation for clinical and research magnetic resonance imaging systems. When activated, this mode will be designed to restrict the static and time varying fields of a system to predefined thresholds. The purpose of this mode is to allow device manufacturers to prospectively design and test implants for use in an MRI environment without considering multiple variations between magnets, vendors, or specific sequence factors. In their session Manny and Anne introduced the idea of imaging implants deemed ‘safe’ when scanned under the newly defined FPO mode. Following a brief overview of MR safety considerations for scanning patients with MR conditional devices, Anne and Manny posed a number of clinical scenarios showing how the proposed mode might prove clinically useful in various imaging settings. The final section of the forum was dedicated to a panel discussion on the future of MR safety. All six presenters took to the stage to give their perspective on how we may move forward into a new era of understanding in MR safety. Much of the discussion revolved around the potential implementation of the proposed FPO: Basic mode, how this will affect existing implants as well as future testing of implants and devices. There was some lively discussion regarding responsibilities and liabilities of device manufacturers, magnet vendors, and MRI practitioners; and a commitment made to continue the discussions with all parties in the coming months and years. You are invited to join the discussion online via the MRI list serve. The MRI listserve, managed by the SMRT, is an excellent resource to discuss matters. |
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