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Volumetric MRI‐guided high‐intensity focused ultrasound for noninvasive, in vivo determination of tissue thermal conductivity: Initial experience in a pig model
Author(s) -
Zhang Jiming,
Mougenot Charles,
Partanen Ari,
Muthupillai Raja,
Hor PeiHerng
Publication year - 2013
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.23878
Subject(s) - high intensity focused ultrasound , ultrasound , in vivo , intensity (physics) , biomedical engineering , materials science , thermal conductivity , magnetic resonance imaging , medicine , radiology , nuclear magnetic resonance , physics , optics , biology , microbiology and biotechnology , composite material
Abstract Purpose: To estimate the local thermal conductivity of porcine thigh muscle at temperatures required for magnetic resonance imaging (MRI)‐guided high‐intensity focused ultrasound (MRgHIFU) surgery (60–90°C). Materials and Methods: Using MRgHIFU, we performed 40 volumetric ablations in the thigh muscles of four pigs. Thirty‐five of the sonications were successful. We used MRI to monitor the resulting temperature increase. We then determined local thermal conductivity by analyzing the spatiotemporal spread of temperature during the cooling period. Results: The thermal conductivity of MRgHIFU‐treated porcine thigh muscle fell within a narrow range (0.52 ± 0.05 W/[m*K]), which is within the range reported for porcine thigh muscle at temperatures of <40°C (0.52 to 0.62 W/[m*K]). Thus, there was little change in the thermal conductivity of porcine thigh muscle at temperatures required for MRgHIFU surgery compared to lower temperatures. Conclusion: Our MRgHIFU‐based approach allowed us to estimate, with good reproducibility, the local thermal conductivity of in vivo deep tissue in real time at temperatures of 60°C to 90°C. Therefore, our method provides a valuable tool for quantifying the influence of thermal conductivity on temperature distribution in tissues and for optimizing thermal dose delivery during thermal ablation with clinical MRgHIFU. J. Magn. Reson. Imaging 2013;37:950–957. © 2012 Wiley Periodicals, Inc.