In vivo radiofrequency heating in swine in a 3T (123.2‐MHz) birdcage whole body coil. Issue 4 (20th November 2013)

• Record Type: Journal Article
• Authors: Shrivastava, Devashish; Utecht, Lynn; Tian, Jinfeng; Hughes, John; Vaughan, J. Thomas
• Is Part Of: Magnetic resonance in medicine. Volume 72:Issue 4(2014:Oct.)
• Page Start: 1141
• Page End: 1150
• Publication Date: 2013-11-20
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.24999
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm24999-sec-0001" sec-type="section"> <title>Purpose</title> <p>To study in vivo radiofrequency (RF) heating produced due to power deposition from a 3T (Larmour frequency = 123.2 MHz), birdcage, whole body coil.</p> </sec> <sec id="mrm24999-sec-0002" sec-type="section"> <title>Methods</title> <p>The RF heating was simulated in a digital swine by solving the mechanistic generic bioheat transfer model (GBHTM) and the conventional, empirical Pennes bioheat transfer equation for two cases: 1) when the swine head was in the isocenter and 2) when the swine trunk was in the isocenter. The simulation results were validated by making direct fluoroptic temperature measurements in the skin, brain, simulated hot regions, and rectum of 10 swine (case 1: n = 5, mean animal weight = 84.03 ± 6.85 kg, whole body average SAR = 2.65 ± 0.22 W/kg; case 2: n = 5, mean animal weight = 81.59 ± 6.23 kg, whole body average SAR = 2.77 ± 0.26 W/kg) during 1 h of exposure to a turbo spin echo sequence.</p> </sec> <sec id="mrm24999-sec-0003" sec-type="section"> <title>Results</title> <p>The GBHTM simulated the RF heating more accurately compared with the Pennes equation. In vivo temperatures exceeded safe temperature thresholds with allowable SAR exposures. Hot regions may be produced deep inside the body, away from the skin.</p> </sec> <sec id="mrm24999-sec-0004" sec-type="section"> <title>Conclusion</title> <p>SAR exposures that produce safe temperature thresholds need reinvestigation. <bold>Magn Reson Med 72:1141–1150, 2014. © 2013 Wiley Periodicals, Inc</bold>.</p> </sec> </abstract>