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MRI monitoring of the thermal ablation of tissue: Effects of long exposure times
Author(s) -
McDannold Nathan,
Hynynen Kullervo,
Jolesz Ferenc
Publication year - 2001
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.1061
Subject(s) - swelling , thermal ablation , biomedical engineering , materials science , focused ultrasound , ablation , ultrasound , thermocouple , subtraction , biological tissue , medicine , radiology , arithmetic , mathematics , composite material
MRI‐derived thermometry based on the temperature‐dependence of the proton resonant frequency (PRF) is extremely sensitive to changes in tissue unrelated to temperature changes, including tissue swelling. This study investigated the maximum amount of time that this phase‐subtraction‐based method can be used to accurately monitor temperature changes in vivo. Long‐duration focused ultrasound sonications were delivered in rabbit thigh muscle with a phased‐array transducer, and the time that tissue swelling began was monitored. Tissue swelling began to occur at about one minute. The temperature correlated well with an implanted thermocouple up to this time. After this time, severe artifacts in the phase‐difference maps were observed. The thermal dose model predicted the extent of tissue damage well for subsequent one minute sonications. These results will have implications for MRI guidance of thermal therapies with long exposure times. J. Magn. Reson. Imaging 2001;13:421–427. © 2001 Wiley‐Liss, Inc.