TY - GEN
T1 - Image-guided Ex vivo liver ablation by unfocused ultrasound using passive cavitation detection
AU - Salgaonkar, Vasant A.
AU - Karunakaran, Chandra Priya
AU - Besse, John A.
AU - Heinlein, Grace
AU - Datta, Saurabh
AU - Holland, Christy K.
AU - Mast, T. Douglas
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2007
Y1 - 2007
N2 - Ablation therapy is used as an alternative to surgical resection of hepatic tumors. In ablation, tumors are destroyed through heating by RF current, high intensity focused ultrasound (HIFU), or other energy sources. Ablation can be performed with a linear array transducer delivering unfocused intense ultrasound (>10 W/cm2). This allows simultaneous treatment and imaging, a feature uncommon in RF ablation. Unfocused ultrasound can also enable faster bulk tissue ablation than HIFU. In the experiments reported here, a 32-element linear array transducer with a 49 mm aperture delivers 3.1 MHz continuous wave unfocused ultrasound at amplitudes 0.7-1.4 MPa during the therapy cycle. It also operates in pulse-echo mode to capture B-scan images. Ex-vivo fresh bovine liver tissue placed in degassed saline is exposed to continuous wave ultrasound interleaved with brief pulsed ultrasound imaging cycles. Tissue exposures range between 5 to 20 minutes. The following measurements are made at intervals of 1 to 3 seconds: tissue temperature with a needle thermocouple, acoustic emissions with a 1 MHz passive unfocused detector, and tissue echogenicity from image brightness. Passively detected acoustic emissions are used to quantify cavitation activity in the ablation experiments presented here. As severity and extent of tissue ablation are related to temperature, this paper will statistically model temperature as a function of tissue echogenicity and cavitation. The latter two quantities can potentially be monitored noninvasively and used as a surrogate for temperature, enabling improved image guidance and control of ultrasound ablation.
AB - Ablation therapy is used as an alternative to surgical resection of hepatic tumors. In ablation, tumors are destroyed through heating by RF current, high intensity focused ultrasound (HIFU), or other energy sources. Ablation can be performed with a linear array transducer delivering unfocused intense ultrasound (>10 W/cm2). This allows simultaneous treatment and imaging, a feature uncommon in RF ablation. Unfocused ultrasound can also enable faster bulk tissue ablation than HIFU. In the experiments reported here, a 32-element linear array transducer with a 49 mm aperture delivers 3.1 MHz continuous wave unfocused ultrasound at amplitudes 0.7-1.4 MPa during the therapy cycle. It also operates in pulse-echo mode to capture B-scan images. Ex-vivo fresh bovine liver tissue placed in degassed saline is exposed to continuous wave ultrasound interleaved with brief pulsed ultrasound imaging cycles. Tissue exposures range between 5 to 20 minutes. The following measurements are made at intervals of 1 to 3 seconds: tissue temperature with a needle thermocouple, acoustic emissions with a 1 MHz passive unfocused detector, and tissue echogenicity from image brightness. Passively detected acoustic emissions are used to quantify cavitation activity in the ablation experiments presented here. As severity and extent of tissue ablation are related to temperature, this paper will statistically model temperature as a function of tissue echogenicity and cavitation. The latter two quantities can potentially be monitored noninvasively and used as a surrogate for temperature, enabling improved image guidance and control of ultrasound ablation.
KW - Cavitation
KW - Logistic regression
KW - Monitoring
KW - Statistical modeling
KW - Temperature
KW - Ultrasound ablation
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U2 - 10.1117/12.701029
DO - 10.1117/12.701029
M3 - Conference contribution
AN - SCOPUS:34548244974
SN - 0819465534
SN - 9780819465535
T3 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE
BT - Thermal Treatment of Tissue
T2 - Thermal Treatment of Tissue: Energy Delivery and Assessment IV
Y2 - 20 January 2007 through 21 January 2007
ER -