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CEM43°C thermal dose thresholds: a potential guide for magnetic resonance radiofrequency exposure levels?

  • Magnetic Resonance
  • Published:
European Radiology Aims and scope Submit manuscript

Abstract

Objective

To define thresholds of safe local temperature increases for MR equipment that exposes patients to radiofrequency fields of high intensities for long duration. These MR systems induce heterogeneous energy absorption patterns inside the body and can create localised hotspots with a risk of overheating.

Methods

The MRI + EUREKA research consortium organised a “Thermal Workshop on RF Hotspots”. The available literature on thresholds for thermal damage and the validity of the thermal dose (TD) model were discussed.

Results/Conclusions

The following global TD threshold guidelines for safe use of MR are proposed:

  1. 1.

    All persons: maximum local temperature of any tissue limited to 39 °C

  2. 2.

    Persons with compromised thermoregulation AND

    1. (a)

      Uncontrolled conditions: maximum local temperature limited to 39 °C

    2. (b)

      Controlled conditions: TD < 2 CEM43°C

  3. 3.

    Persons with uncompromised thermoregulation AND

    1. (a)

      Uncontrolled conditions: TD < 2 CEM43°C

    2. (b)

      Controlled conditions: TD < 9 CEM43°C

The following definitions are applied:

Controlled conditions:

A medical doctor or a dedicated trained person can respond instantly to heat-induced physiological stress

Compromised thermoregulation:

All persons with impaired systemic or reduced local thermoregulation

Key Points

• Standard MRI can cause local heating by radiofrequency absorption.

• Monitoring thermal dose (in units of CEM43°C) can control risk during MRI.

• 9 CEM43°C seems an acceptable thermal dose threshold for most patients.

• For skin, muscle, fat and bone,16 CEM43°C is likely acceptable.

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Notes

  1. This workshop was co-sponsored by the Mobile Manufacturers Forum, the GSM Association, and the US Food and Drug Administration. A selection of the presentations are published in the Special Issue entitled “Thermal Aspects of Radio Frequency Exposure on Human Health”; Int. J. Hyperthermia; 4, 2011. Guest Editor: Joseph Morrissey.

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Acknowledgements

This study was supported by the EUREKA (E4144) and CTI (9193.1) project MRI+. This study was also supported by The Netherlands Organization for Health Research and Development ZonMw project 85400003 and project 85800002.

Author information

Authors and Affiliations

  1. Department of Radiotherapy, Erasmus MC Cancer Center, Rotterdam, The Netherlands

    Gerard C. van Rhoon

  2. Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece

    Theodoros Samaras

  3. Department of Biomedical Engineering, Duke University, Durham, NC, USA

    Pavel S. Yarmolenko

  4. Center for Interventional Oncology, Radiology and Imaging Sciences, NIH, Bethesda, MD, USA

    Pavel S. Yarmolenko

  5. Department of Pathology & Department of Radiation Oncology, Duke University, Durham, NC, USA

    Mark W. Dewhirst

  6. IT’IS Foundation, Zurich, Switzerland

    Esra Neufeld & Niels Kuster

  7. Department Radiation Oncology, Unit Hyperthermia, Room GS-02, Box 5201, 3008 AE, Rotterdam, The Netherlands

    Gerard C. van Rhoon

Authors
  1. Gerard C. van Rhoon
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  2. Theodoros Samaras
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  3. Pavel S. Yarmolenko
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  4. Mark W. Dewhirst
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  5. Esra Neufeld
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  6. Niels Kuster
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Corresponding author

Correspondence to Gerard C. van Rhoon.

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van Rhoon, G.C., Samaras, T., Yarmolenko, P.S. et al. CEM43°C thermal dose thresholds: a potential guide for magnetic resonance radiofrequency exposure levels?. Eur Radiol 23, 2215–2227 (2013). https://doi.org/10.1007/s00330-013-2825-y

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  • DOI: https://doi.org/10.1007/s00330-013-2825-y

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