In vivo T2‐based MR thermometry in adipose tissue layers for high‐intensity focused ultrasound near‐field monitoring. Issue 4 (20th November 2013)

• Record Type: Journal Article
• Authors: Baron, Paul; Ries, Mario; Deckers, Roel; de Greef, Martijn; Tanttu, Jukka; Köhler, Max; Viergever, Max A.; Moonen, Chrit T. W.; Bartels, Lambertus W.
• Is Part Of: Magnetic resonance in medicine. Volume 72:Issue 4(2014:Oct.)
• Page Start: 1057
• Page End: 1064
• Publication Date: 2013-11-20
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.25025
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm25025-sec-0001" sec-type="section"> <title>Purpose</title> <p>During MR‐guided high‐intensity focused ultrasound (HIFU) therapy, ultrasound absorption in the near field represents a safety risk and limits efficient energy deposition at the target. In this study, we investigated the feasibility of using T<sub>2</sub> mapping to monitor the temperature change in subcutaneous adipose tissue layers.</p> </sec> <sec id="mrm25025-sec-0002" sec-type="section"> <title>Methods</title> <p>The T<sub>2</sub> temperature dependence and reversibility was determined for fresh adipose porcine samples. The accuracy was evaluated by comparing T<sub>2</sub>‐based temperature measurements with probe readings in an ex vivo HIFU experiment. The in vivo feasibility of T<sub>2</sub>‐based thermometry was studied during HIFU ablations in the liver in pigs and of uterine fibroids in human patients.</p> </sec> <sec id="mrm25025-sec-0003" sec-type="section"> <title>Results</title> <p>T<sub>2</sub> changed linearly and reversibly with temperature with an average coefficient of 5.2 ± 0.1 ms/°C. For the ex vivo HIFU experiment, the difference between the T<sub>2</sub>‐based temperature change and the probe temperature was <0.9°C. All in vivo experiments showed temperature‐related T<sub>2</sub> changes in the near field directly after sonications. As expected, considerable intersubject variations in the cooling times were measured in the in vivo porcine experiments.</p> </sec> <sec id="mrm25025-sec-0004" sec-type="section"> <title>Conclusions</title> <p>The reversibility and linearity of the T<sub>2</sub>‐temperature dependence of adipose tissue allows for the monitoring of the temperature in the subcutaneous adipose tissue layers. Magn Reson Med 72:1057–1064, 2014. © 2013 Wiley Periodicals, Inc.</p> </sec> </abstract>