title: 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.
  
  
  CONCLUSIONS
  The following global TD threshold guidelines for safe use of MR are proposed: 1. All persons: maximum local temperature of any tissue limited to 39 °C 2. Persons with compromised thermoregulation AND (a) Uncontrolled conditions: maximum local temperature limited to 39 °C (b) Controlled conditions: TD < 2 CEM43°C 3. Persons with uncompromised thermoregulation AND (a) Uncontrolled conditions: TD < 2 CEM43°C (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
  
  
  CONCLUSIONS
  • 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.
authors.affiliation: Department of Radiotherapy, Erasmus MC Cancer Center, Rotterdam, The Netherlands. g.c.vanrhoon@erasmusmc.nl
authors.forename: Gerard C
authors.initials: GC
authors.lastname: van Rhoon
authors.forename: Theodoros
authors.initials: T
authors.lastname: Samaras
authors.forename: Pavel S
authors.initials: PS
authors.lastname: Yarmolenko
authors.forename: Mark W
authors.initials: MW
authors.lastname: Dewhirst
authors.forename: Esra
authors.initials: E
authors.lastname: Neufeld
authors.forename: Niels
authors.initials: N
authors.lastname: Kuster
mesh_terms: D000042:Absorption; D000818:Animals; D001831:Body Temperature; D001921:Brain / Q000473:pathology; D006706:Homeostasis; D006358:Hot Temperature; D006801:Humans; D006979:Hyperthermia, Induced / Q000009:adverse effects / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000009:adverse effects* / Q000379:methods*; D017410:Practice Guidelines as Topic; D011846:Radio Waves; D013045:Species Specificity; D013997:Time Factors; D014018:Tissue Distribution
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