Feasibility of Measuring Thermoregulation during RF Heating of the Human Calf Muscle Using MR Based Methods: Measuring Thermoregulation During RF Heating

Frank F. J. Simonis, Esben Thade Petersen, Jan J. W. Lagendijk, Cornelis A. T. van den Berg

Research output: Contribution to journalJournal articleResearchpeer-review


Purpose: One of the main safety concerns in MR is heating of the subject due to radiofrequency (RF) exposure. Recently was shown that local peak temperatures can reach dangerous values and the most prominent parameter for accurate temperature estimations is thermoregulation. Therefore, the goal of this research is testing the feasibility of measuring thermoregulation in vivo using MR methods.Theory and Methods: The calves of 13 volunteers were scanned at 3 tesla. A Proton Resonance Frequency Shift method was used for temperature measurement. Arterial Spin Labeling and phase contrast scans were used for perfusion and flow measurements respectively. The calves were monitored during extreme RF exposure (20 W/kg, 16 min) and after physical exercise.Results: Temperature increases due to RF absorption (range of the 90th percentile of all volunteers: 1.1-2.5 degrees C) matched with the reference skin temperature changes. Increases in perfusion and flow were defined on the whole leg and normalized to baseline. Perfusion showed a significant increase due to RF heating (ratio compared with baseline: 1.28 +/- 0.37; P <0.05), the influence of exercise was much greater, however (2.97 +/- 2.45, P <0.01).Conclusion: This study represents a first exploration of measuring thermoregulation, which will become essential when new safety guidelines are based on thermal dose. (C) 2015 Wiley Periodicals, Inc.
Original languageEnglish
JournalMagnetic Resonance in Medicine
Issue number4
Pages (from-to)1743-1751
Publication statusPublished - 2015
Externally publishedYes


  • Radiology, Nuclear Medicine and Imaging
  • ASL
  • calf muscle
  • MR thermometry
  • RF safety
  • thermoregulation
  • artery
  • calf (mammal)
  • drug dosage form
  • exercise
  • exposure
  • feasibility study
  • flow measurement
  • gastrocnemius muscle
  • heating
  • human
  • leg
  • major clinical study
  • perfusion
  • practice guideline
  • radiofrequency
  • safety
  • skin temperature
  • spin labeling
  • temperature measurement
  • theoretical model
  • volunteer
  • SAR
  • Bio-optics (effects of microwaves, light, laser and other electromagnetic waves)
  • Haemodynamics, pneumodynamics
  • Medical magnetic resonance imaging and spectroscopy
  • Patient diagnostic methods and instrumentation
  • Biothermics
  • Thermometry
  • Health Physics
  • Biomedical magnetic resonance imaging and spectroscopy
  • Thermal variables measurement
  • biological effects of microwaves
  • biomedical MRI
  • biothermics
  • blood flow measurement
  • muscle
  • radiofrequency heating
  • RF heating
  • human calf muscle
  • MR based method
  • radiofrequency exposure
  • local peak temperatures
  • temperature estimations
  • Proton Resonance Frequency Shift method
  • Arterial Spin Labeling
  • phase contrast scans
  • perfusion measurement
  • extreme RF exposure
  • physical exercise
  • RF absorption
  • reference skin temperature changes
  • thermal dose
  • magnetic flux density 3 T
  • time 16 min
  • Mathematical biology and statistical methods
  • Muscle - Physiology and biochemistry
  • Animals, Chordates, Humans, Mammals, Primates, Vertebrates
  • radiofrequency safety


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