OCTOBER 2014 • Vol. 3, Issue 4

Safety Workshops Highlight Work in Progress

Several of the SMRT membership attended one or both Safety focused events in Washington DC, USA 5-9 September. The first was the Safety Workshop three-day conference sponsored by the ISMRM/SMRT. Immediately following the workshop was Dr. Emanuel Kanal’s MR Safety Officer Training course. Five days of MR safety! An incredible amount of pertinent material and research in MR safety was presented by engaging speakers!

I want to highlight just a few nuggets of information I gleaned during the five days. So much information is available that I will not do it justice in this short article. If you are a member of the SMRT/ISMRM I encourage you to review the talks on the SMRT website when they are made available.

The first topic to discuss is the overall safety record in our profession. While incidents are not daily they continue to occur and patients, in all parts of the world, are injured. Projectiles are the issue most lay people see on social media but burns continue to be the persistent and the more common concern. As we move our industry to higher magnet fields all safety issues change. We must keep up with safety risks or we will be in a position of not protecting our patients. Awareness and education are of course the key. As I review data from a variety of MR sites it is obvious we have a long way to go before engaging those people in Radiology that are key to our success.

The FDA is trying many means to help us with implant and device labeling. Terry Woods and Jana Defino (FDA employees) spoke at the Workshop to detail the process for both MR magnet approval and Implant and Device labeling. Unfortunately they can guide but not require devices to be labeled appropriately. As hardware and software evolve the FDA is trying to keep up with the needs of industry and the concerns of the MR community. There will be changes in labeling soon. The SMRT safety committee’s members are trying to stay on top of this and will provide information when this takes place.

On a more scientific note each of the three main areas for safety concerns: static field, gradient switching and radiofrequency (RF), had a day of presentations at the ISMRM/SMRT Workshop. After each forum, there were discussion sessions which often became lively. Here are the highlights:

1. Static Magnetic Field- The industry is moving towards 7T. While there are no clinical magnets many research magnets have been installed around the world. Image quality is high, artifacts are prevalent and MR safety is still being ironed out. Many implants and devices have not been tested. Deaths due to static field are still very low but we must be diligent.

2. Gradient switching - Have the dual concern of noise as well as possible current induction. Multiple speakers explored this and it seems clear that in normal scanning mode the risk of induced current for peripheral nerve stimulation or heating from gradients switching is low. However, the threat to active devices is real. Following manufacturer’s tested guidelines is imperative. Hearing damage, on the other hand, is a real day to day issue. All persons who will remain in the scan room while pulse sequences are being performed must wear hearing protection that reduces noise to about 90 dBs or less.

3. Radio Frequency (RF)
   

   1. RF can, will, and does produce burns on patients.
   2. Most of the MAUDE reports (events reported to FDA) are RF related.
   3. At 1.5T the frequency is in the radio-wave range; as we go towards 7T we are getting closer to low end of microwave. The RF transmission is non-ionizing radiation at all fields but of course has more energy as we go up in MHz.
   4. The RF pulse (electromagnetic wave) has 2 components:
      i. Magnetism-No heating issues
      ii. Electrical signal-potential to create burns.
   5. As wires get closer to the resonance frequency, heating becomes an issue. In general, shorter wires at higher field increase the safety risk.
   6. Measuring RF Heating was a topic of much debate. Several speakers bemoaned SAR as a measure and suggested instead measuring temperature rise. This could be accomplished by several means and was felt by most to be the better indicator of heating.

Several great technologist speakers highlighted MR suite safety, education and screening in clinical, research and pediatric scenarios. We learned that nothing is “safe” unless the only way it can hurt you is if someone throws it at you! Test everything, follow manufacturer instructions, screen everyone, change everyone and trust NO-ONE.

Dr. Kanal thoroughly covered each of the MR safety topics in this, the 2nd of his MR Safety Officer (MRSO) educational seminars. Special attention was given to legal implications for safety related accidents. He also covered contrast and we learned about the make-up and safety profile of each of the FDA approved agents. The key message was each MRSO must be educated so they may give guidance to the rest of the MR team. Dr. Kanal recommends that sites appoint a Safety Officer who works under the MR Medical Director. For those sites that have Physicists a MR Expert would also be added to the safety group. This group works together to set policy, investigate implants and guide the Radiologist in safety issues. According to Dr. Kanal, the ultimate responsibility rests with the Radiologist but he depends on the MRSO for guidance.

The SMRT is striving to stay informed of new developments and respond with data and education for the MR community, as new information becomes available. Thanks to all who participated in the workshops and meetings. These were wonderful opportunities to learn and network with others grappling with day to day MR safety issues.