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

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. 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.

References

  1. 1.

    Dewhirst MW, Vujaskovic Z, Jones E, Thrall D (2005) Re-setting the biologic rationale for thermal therapy. Rev Int J Hyperthermia 21:779–790

  2. 2.

    Horsman MR, Overgaard J (2007) Hyperthermia: a potent enhancer of radiotherapy. Clin Oncol 19:418–426

  3. 3.

    Ryan TP, Turner PF, Hamilton B (2010) Interstitial microwave transition form hyperthermia to ablation: historical perspectives and current trends in thermal therapy. Int J Hyperthermia 26:415–433

  4. 4.

    Rempp H, Hoffmann R, Roland J, Buck A, Kickhefel A, Claussen CD, Pereira PL, Schick F, Clasen S (2012) Threshold-based prediction of the coagulation zone in sequential temperature mapping in MR-guided radiofrequency ablation of liver tumours. Eur Radiol 22:1091–1100

  5. 5.

    Terraz S, Cernicanu A, Lepetit-Coiffé M, Viallon M, Salomir R, Mentha G, Becker CD (2010) Radiofrequency ablation of small liver malignancies under magnetic resonance guidance: progress in targeting and preliminary observations with temperature monitoring. Eur Radiol 20:886–897

  6. 6.

    Lepetit-Coiffé M, Laumonier H, Seror O, Quesson B, Sesay MB, Moonen CT, Grenier N, Trillaud H (2010) Real-time monitoring of radiofrequency ablation of liver tumors using thermal-dose calculation by MR temperature imaging: initial results in nine patients, including follow-up. Eur Radiol 20:193–201

  7. 7.

    Qian GJ, Wang N, Shen Q, Sheng YH, Zhao JQ, Kuang M, Liu GJ, Wu MC (2012) Efficacy of microwave versus radiofrequency ablation for treatment of small hepatocellular carcinoma: experimental and clinical studies. Eur Radiol 22:1983–1990

  8. 8.

    Marshall J, Martin T, Downie J, Malisza K (2007) A comprehensive analysis of MRI research risks: in support of full disclosure. Can J Neurol Sci 34:11–17

  9. 9.

    International Electrotechnical Commission (2010) IEC 60601-2-33: medical electrical equipment—particular requirements for the basic safety and essential performanceof magnetic resonance equipment for medical diagnosis. IEC, Geneva

  10. 10.

    Murbach M, Cabot E, Neufeld E, Gosselin MC, Christ A, Kuster N (2011) Local SAR enhancements in anatomically correct children and adult models as a function of position within 1.5 T MR body coil. Prog Biophys Mol Biol 3:428–433

  11. 11.

    Nadobny J, Szimtenings M, Diehl D, Stetter E, Brinker G, Wust P (2007) Evaluation of MR-induced hot spots for different temporal SAR modes using a time-dependent temperature gradient treatment. IEEE Trans Biomed Eng 54:1837–1850

  12. 12.

    Neufeld E, Gosselin MC, Murbach M, Christ A, Cabot E, Kuster N (2011) Analysis of the local worst-case SAR exposure caused by an MRI multi-transmit body coil in anatomical models of the human body. Phys Med Biol 56:4649–4659

  13. 13.

    Sapareto SA, Dewey WC (1984) Thermal dose determination in cancer therapy. Int J Radiat Oncol Biol Phys 10:787–800

  14. 14.

    Dewhirst MW, Viglianti BL, Lora-Michiels M, Hanson M, Hoopes PJ (2003) Basic principles of thermal dosimetry and thermal thresholds for tissue damage from hyperthermia. Int J Hyperthermia 19:267–294

  15. 15.

    Yarmolenko PS, Moon EJ, Landon C, Manzoor A, Hochman DW, Viglianti BL, Dewhirst MW (2011) Thresholds for thermal damage to normal tissues: An update. Int J Hyperthermia 26:1–26

  16. 16.

    Dewey WC (1994) Arrhenius relationships from the molecule and cell to the clinic. Int J Hyperthermia 10:457–483

  17. 17.

    Hall EJ, Roizin-Towle L (1984) Biological effects of heat. Cancer Res 44:4708s–4713s

  18. 18.

    Field SB, Morris CC (1983) The relationship between heating time and temperature: its relevance to clinical hyperthermia. Radiother Oncol 1:179–186

  19. 19.

    Ichinoseki-Sekine N, Naito H, Saga N, Ogura Y, Shiraishi M, Giombini A, Giovannini V, Katamoto S (2007) Changes in muscle temperature induced by 434 MHz microwave hyperthermia. Br J Sports Med 41:425–429

  20. 20.

    Beachy SH, Repasky EA (2011) Toward establishment of temperature thresholds for immunological impact of heat exposure in humans. Int J Hyperthermia 27:344–352

  21. 21.

    Wetsel WC (2011) Hyperthermic effects on behavior. Int J Hyperthermia 27:353–373

  22. 22.

    Ziskin MC, Morrissey J (2011) Thermal thresholds for teratogenicity, reproduction, and development. Int J Hyperthermia 27:374–387

  23. 23.

    Wetsel WC (2011) Sensing hot and cold with TRP channels. Int J Hyperthermia 27:388–398

  24. 24.

    van Rhoon GC, Aleman A, Kelfkens G et al (2011) The Electromagnetic Fields Committee of the Health Council of the Netherlands Health Council of the Netherlands: no need to change from SAR to time-temperature relation in electromagnetic fields exposure limits. Int J Hyperthermia 27:399–404

  25. 25.

    Foster KR, Morrissey JJ (2011) Thermal aspects of exposure to radiofrequency energy: report of a workshop. Int J Hyperthermia 27:307–319

  26. 26.

    Hoopes P, Wishnow K, Bartholomew L et al (2000) Evaluation and comparison of five experimental BPH/prostate cancer treatment modalities. In: A critical review: matching the energy source to the clinical need, CR 75. SPIE Opt Eng Press, Bellingham, Washington, p 519–545

  27. 27.

    Moritz A, Henriques F (1947) Studies of thermal injury II. The relative importance of time and surface temperature in the causation of thermal burns. Am J Pathol 23:695–720

  28. 28.

    Harris A, Erickson L, Kendig J, Mingrino S, Goldring S (1962) Observations on selective brain heating in dogs. J Neurosurg 19:514–521

  29. 29.

    Prionas SD, Taylor MA, Fajardo LF, Kelly NI, Nelsen TS, Hahn GM (1985) Thermal sensitivity to single and double heat treatments in normal canine liver. Cancer Res 45:4791–4797

  30. 30.

    Guy A, Lin J, Kramar P, Emery A (1975) Effect of 2450-MHz radiation on the rabbit eye. IEEE Trans Microw Theory Tech 23:492–498

  31. 31.

    Marigold JC, Hume SP, Hand JW (1985) Investigation of thermotolerance in mouse testis. Int J Radiat Biol Relat Stud Phys Chem Med 48:589–595

  32. 32.

    Hand JW, Li Y, Hajnal JV (2010) Numerical study of RF exposure and the resulting temperature rise in the foetus during a magnetic resonance procedure. Phys Med Biol 55:913–930

  33. 33.

    Asakura H (2004) Fetal and neonatal thermoregulation. J Nippon Med Sch 71:360–370

  34. 34.

    Miller MW, Nyborg WL, Dewey WC, Edwards MJ, Abramowicz JS, Brayman AA (2002) Hyperthermic teratogenicity, thermal dose and diagnostic ultrasound during pregnancy: implications of new standards on tissue heating. Int J Hyperthermia 18:361–384

  35. 35.

    Heynick LN, Merritt JH (2003) Radiofrequency fields and teratogenesis. Bioelectromagnetics S6:s174–s186

  36. 36.

    Nomoto S, Shibata M, Iriki M, Riedel W (2004) Role of afferent pathways of heat and cold in body temperature regulation. Int J Biometeorol 49:67–85

  37. 37.

    Yang M, Christoforidis G, Abdujali A, Beversdorf D (2006) Vital signs investigation in subjects undergoing MR imaging at 8T. Am J Neuroradiol 27:922–928

  38. 38.

    Bernardi P, Cavagnaro M, Pisa S, Piuzzi E (2003) Specific absorption rate and temperature elevation in a subject exposed in the far-field of radio-frequency sources operating in the 10–900-MHz range. IEEE Trans Biomed Eng 50:295–304

  39. 39.

    Hirata A, Asano T, Fujiwara O (2008) FDTD analysis of body-core temperature elevation in children and adults for whole-body exposure. Phys Med Biol 53:5223–5238

  40. 40.

    Bakker JF, Paulides MM, Neufeld E, Christ A, Kuster N, van Rhoon GC (2011) Children and adults exposed to electromagnetic fields at the ICNIRP reference levels: theoretical assessment of the induced peak temperature increase. Phys Med Biol 56:4967–4989

  41. 41.

    Van der Wal E, Franckena M, Wielheesen DHM, van der Zee J, van Rhoon GC (2008) Steering in locoregional deep hyperthermia: evaluation of common practice with 3D-planning. Int J Hyperthermia 24:682–693

  42. 42.

    Kiyatkin EA, Sharma HS (2009) Permeability of the blood–brain barrier depends on brain temperature. Neuroscience 161:926–939

  43. 43.

    Kiyatkin EA (2005) Brain hyperthermia as physiological and pathological phenomena. Brain Res Rev 50:27–56

  44. 44.

    Versteegh PMR (1980) Gegeneraliseerde Hyperthermie, een klinische methode. PhD thesis. Leiden University, 19 June 1980

  45. 45.

    Van Rhoon GC, van der Zee J (1983) Cerebral temperature and epidural pressure during whole body hyperthermia in dogs. Res Exp Med 183:47–54

  46. 46.

    Main PW, Lovell ME (1996) A review of seven support surfaces with emphasis on their protection of the spinally injured. J Accid Emerg Med 13:34–37

  47. 47.

    Suzuki T, Hirayama T, Aihara K, Hirohata Y (1991) Experimental studies of moderate temperature burns. Burns 17:443–451

  48. 48.

    Greenhalgh DG, Lawless MB, Chew BB, Crone WA, Fein ME, Palmieri TL (2004) Temperature threshold for burn injury: an oximeter safety study. J Burn Care Rehabil 25:411–415

  49. 49.

    Werner MU, Lassen B, Pedersen JL, Kehlet H (2002) Local cooling does not prevent hyperalgesia following burn injury in humans. Pain 98:297–303

  50. 50.

    Franco W, Kothare A, Ronan SJ, Grekin RC, McCalmont TH (2010) Hyperthermic injury to adipocyte cells by selective heating of subcutaneous fat with a novel radiofrequency device: feasibility studies. Lasers Surg Med 42:361–370

  51. 51.

    Martinez AA, Meshorer A, Meyer JL, Hahn GM, Fajardo LF, Prionas SD (1983) Thermal sensitivity and thermotolerance in normal porcine tissues. Cancer Res 43:2072–2075

  52. 52.

    Eriksson AR, Albrektsson T (1983) Temperature threshold levels for heat-induced bone tissue injury: a vital-microscopic study in the rabbit. J Prosthetic Dentistry 50:101–107

  53. 53.

    Graesslin I, Homann H, Biederer S, Börnert P, Nehrke K, Vernickel P, Mens G, Harvey P, Katscher U (2012) A specific absorption rate prediction concept for parallel transmission MR. Magn Reson Med 68:1664–1674

  54. 54.

    Wolf S, Diehl D, Gebhardt M, Mallow J, Speck O (2012) SAR simulations for high-field MRI: How much detail, effort, and accuracy is needed? Magn Reson Med. doi:10.1002/mrm.24329

  55. 55.

    Fowlkes JB, Abramowicz JS, Jacques S et al (2008) American Institute of Ultrasound in Medicine consensus report on potential bioeffects of diagnostic ultrasound. J Ultrasound Med 27:503–515

  56. 56.

    O’Brien WD Jr, Deng CX, Harris GR et al (2008) The risk of exposure to diagnostic ultrasound in postnatal subjects: thermal effects. J Ultrasound Med 27:517–535

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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.

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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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Keywords

  • MRI
  • Thermal dose
  • Thermal threshold
  • Radiofrequency
  • CEM43°C
  • Safe exposure