Thermal Tissue Damage Model Analyzed for Different Whole-Body SAR and Scan Durations for Standard MR Body Coils
Article first published online: 14 FEB 2013
Copyright © 2013 Wiley Periodicals, Inc.
Magnetic Resonance in Medicine
Volume 71, Issue 1, pages 421–431, January 2014
How to Cite
Murbach, M., Neufeld, E., Capstick, M., Kainz, W., Brunner, D. O., Samaras, T., Pruessmann, K. P. and Kuster, N. (2014), Thermal Tissue Damage Model Analyzed for Different Whole-Body SAR and Scan Durations for Standard MR Body Coils. Magn Reson Med, 71: 421–431. doi: 10.1002/mrm.24671
- Issue published online: 17 DEC 2013
- Article first published online: 14 FEB 2013
- Manuscript Accepted: 9 JAN 2013
- Manuscript Revised: 19 DEC 2012
- Manuscript Received: 6 JUL 2012
- EUREKA. Grant Number: E!4144
- CTI. Grant Number: 9193.1 (MRI+ Project)
- local field enhancement;
- thermal dose;
This article investigates the safety of radiofrequency induced local thermal hotspots within a 1.5T body coil by assessing the transient local peak temperatures as a function of exposure level and local thermoregulation in four anatomical human models in different Z-positions.
To quantize the effective thermal stress of the tissues, the thermal dose model cumulative equivalent minutes at 43°C was employed, allowing the prediction of thermal tissue damage risk and the identification of potentially hazardous MR scan-scenarios. The numerical results were validated by B1+− and skin temperature measurements.
At continuous 4 W/kg whole-body exposure, peak tissue temperatures of up to 42.8°C were computed for the thermoregulated model (60°C in nonregulated case). When applying cumulative equivalent minutes at 43°C damage thresholds of 15 min (muscle, skin, fat, and bone) and 2 min (other), possible tissue damage cannot be excluded after 25 min for the thermoregulated model (4 min in nonregulated).
The results are found to be consistent with the history of safe use in MR scanning, but not with current safety guidelines. For future safety concepts, we suggest to use thermal dose models instead of temperatures or SAR. Special safety concerns for patients with impaired thermoregulation (e.g., the elderly, diabetics) should be addressed. Magn Reson Med 71:421–431, 2014. © 2013 Wiley Periodicals, Inc.