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MR monitoring of focused ultrasonic surgery of renal cortex: Experimental and simulation studies
Author(s) -
Hynynen Kullervo,
Damianou Christakis A.,
Colucci Vincent,
Unger Evan,
Cline Harvey H.,
Jolesz Ferenc A.
Publication year - 1995
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.1880050306
Subject(s) - sonication , ultrasound , renal cortex , ultrasonic sensor , focused ultrasound , perfusion , biomedical engineering , kidney , magnetic resonance imaging , transducer , cortex (anatomy) , medicine , materials science , radiology , biology , acoustics , physics , neuroscience
The aim of the study was to test the hypothesis that magnetic resonance (MR) imaging‐guided and ‐monitored noninvasive ultrasonic surgery can be performed in highly perfused tissues from outside the body. A simulation study was performed to evaluate the optimal sonication parameters. An MR‐compatible positioning device was then used to manipulate a focused ultrasound transducer in an MR imager, which was used to sonicate kidneys of five rabbits at various power levels and different durations. Temperature elevation during sonication was monitored with a T1‐ weighted spoiled gradient‐echo sequence. The simulation study demonstrated that a sharply focused transducer and relatively short sonication times (30 seconds or less) are necessary to prevent damage to the overlying skin and muscle tissue, which have a much lower blood perfusion rate than kidney. The experiments showed that the imaging sequence was sensitive enough to show temperature elevation during sonication, thereby Indicating the location of the beam focus. Histologic evaluations showed that kidney necrosis could be consistently induced without damage to overlying skin and muscle. The study demonstrated that highly perfused tissues such as the renal cortex can be coagulated from outside the body with focused ultrasound and that MR imaging can be used to guide and monitor this surgery.