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500‐element ultrasound phased array system for noninvasive focal surgery of the brain: A preliminary rabbit study with ex vivo human skulls
Author(s) -
Hynynen Kullervo,
Clement Gregory T.,
McDannold Nathan,
Vykhodtseva Natalia,
King Randy,
White P. Jason,
Vitek Shuki,
Jolesz Ferenc A.
Publication year - 2004
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.20118
Subject(s) - ex vivo , ultrasound , phased array , skull , biomedical engineering , imaging phantom , materials science , focused ultrasound , in vivo , magnetic resonance imaging , medicine , nuclear medicine , anatomy , radiology , biology , telecommunications , microbiology and biotechnology , computer science , antenna (radio)
The aim of this study was to test a prototype MRI‐compatible focused ultrasound phased array system for trans‐skull brain tissue ablation. Rabbit thigh muscle and brain were sonicated with a prototype, hemispherical 500‐element ultrasound phased array operating at frequencies of 700–800 kHz. An ex vivo human skull sample was placed between the array and the animal tissue. The temperature elevation during 20–30‐sec sonications was monitored using MRI thermometry. The induced focal lesions were observed in T 2 and contrast‐enhanced T 1 ‐weighted fast spin echo images. Whole brain histology evaluation was performed after the sonications. The results showed that sharp temperature elevations can be produced both in the thigh muscle and in the brain. High‐power sonications (600–1080 W) produced peak temperatures up to 55°C and focal lesions that were consistent with thermal tissue damage. The lesion size was found to increase with increasing peak temperature. The device was then modified to operate in the orientation that will be used in the clinic and successfully tested in phantom experiments. As a conclusion, this study demonstrates that it is possible to create ultrasound‐induced lesions in vivo through a human skull under MRI guidance with this large‐scale phased array. Magn Reson Med 52:100–107, 2004. © 2004 Wiley‐Liss, Inc.