Thermal Tissue Damage Model Analyzed for Different Whole‐Body SAR and Scan Durations for Standard MR Body Coils. Issue 1 (14th February 2013)

• Record Type: Journal Article
• Authors: Murbach, Manuel; Neufeld, Esra; Capstick, Myles; Kainz, Wolfgang; Brunner, David O.; Samaras, Theodoros; Pruessmann, Klaas P.; Kuster, Niels
• Is Part Of: Magnetic resonance in medicine. Volume 71:Issue 1(2014:Jan.)
• Page Start: 421
• Page End: 431
• Publication Date: 2013-02-14
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.24671
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm24671-sec-0001" sec-type="section"> <title>Purpose</title> <p>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.</p> </sec> <sec id="mrm24671-sec-0002" sec-type="section"> <title>Methods</title> <p>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 B<sub>1</sub><sup>+</sup>− and skin temperature measurements.</p> </sec> <sec id="mrm24671-sec-0003" sec-type="section"> <title>Results</title> <p>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).</p> </sec> <sec id="mrm24671-sec-0004" sec-type="section"> <title>Conclusion</title> <p>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. <bold>Magn Reson Med 71:421–431, 2014. © 2013 Wiley Periodicals, Inc.</bold></p> </sec> </abstract>