A method for safety testing of radiofrequency/microwave‐emitting devices using MRI. Issue 5 (25th November 2014)

• Record Type: Journal Article
• Authors: Alon, Leeor; Cho, Gene Y.; Yang, Xing; Sodickson, Daniel K.; Deniz, Cem M.
• Is Part Of: Magnetic resonance in medicine. Volume 74:Issue 5(2015:Nov.)
• Page Start: 1397
• Page End: 1405
• Publication Date: 2014-11-25
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.25521
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm25521-sec-0001" sec-type="section"> <title>Purpose</title> <p>Strict regulations are imposed on the amount of radiofrequency (RF) energy that devices can emit to prevent excessive deposition of RF energy into the body. In this study, we investigated the application of MR temperature mapping and 10‐g average specific absorption rate (SAR) computation for safety evaluation of RF‐emitting devices.</p> </sec> <sec id="mrm25521-sec-0002" sec-type="section"> <title>Methods</title> <p>Quantification of the RF power deposition was shown for an MRI‐compatible dipole antenna and a non–MRI‐compatible mobile phone via phantom temperature change measurements. Validation of the MR temperature mapping method was demonstrated by comparison with physical temperature measurements and electromagnetic field simulations. MR temperature measurements alongside physical property measurements were used to reconstruct 10‐g average SAR.</p> </sec> <sec id="mrm25521-sec-0003" sec-type="section"> <title>Results</title> <p>The maximum temperature change for a dipole antenna and the maximum 10‐g average SAR were 1.83°C and 12.4 W/kg, respectively, for simulations and 1.73°C and 11.9 W/kg, respectively, for experiments. The difference between MR and probe thermometry was <0.15°C. The maximum temperature change and the maximum 10‐g average SAR for a cell phone radiating at maximum output for 15 min was 1.7°C and 0.54 W/kg, respectively.</p> </sec> <sec id="mrm25521-sec-0004" sec-type="section"> <title>Conclusion</title> <p>Information acquired using MR temperature mapping and thermal property measurements can assess RF/microwave safety with high resolution and fidelity. Magn Reson Med 74:1397–1405, 2015. © 2014 Wiley Periodicals, Inc.</p> </sec> </abstract>