Document Detail

Active focal zone sharpening for high-precision treatment using histotripsy.
MedLine Citation:
PMID:  21342816     Owner:  NLM     Status:  MEDLINE    
The goal of this study is to develop a focal zone sharpening strategy that produces more precise lesions for pulsed cavitational ultrasound therapy, or histotripsy. Precise and well-confined lesions were produced by locally suppressing cavitation in the periphery of the treatment focus without affecting cavitation in the center. The local suppression of cavitation was achieved using cavitation nuclei preconditioning pulses to actively control cavitation in the periphery of the focus. A 1-MHz 513-element therapeutic array was used to generate both the therapy and the nuclei preconditioning pulses. For therapy, 10-cycle bursts at 100-Hz pulse repetition frequency with P-/P+ pressure of 21/76 MPa were delivered to the geometric focus of the therapeutic array. For nuclei preconditioning, a different pulse was delivered to an annular region immediately surrounding the focus before each therapy pulse. A parametric study on the effective pressure, pulse duration, and delivery time of the preconditioning pulse was conducted in red blood cell-gel phantoms, where cavitational damage was indicated by the color change resulting from local cell lysis. Results showed that a short-duration (20 μs) preconditioning pulse at a medium pressure (P-/P+ pressure of 7.2/13.6 MPa) delivered shortly before (30 μs) the therapy pulse substantially suppressed the peripheral damage by 77 ± 13% while complete fractionation in the focal center was maintained. High-speed imaging of the bubble cloud showed a substantial decrease in the maximum width of the bubble cloud by 48 ± 24% using focal zone sharpening. Experiments in ex vivo livers confirmed that highly confined lesions were produced in real tissues as well as in the phantoms. This study demonstrated the feasibility of active focal zone sharpening using cavitation nuclei preconditioning, allowing for increased treatment precision compared with the natural focal width of the therapy transducer.
Tzu-Yin Wang; Zhen Xu; Timothy Hall; J Fowlkes; William Roberts; Charles Cain
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  IEEE transactions on ultrasonics, ferroelectrics, and frequency control     Volume:  58     ISSN:  1525-8955     ISO Abbreviation:  IEEE Trans Ultrason Ferroelectr Freq Control     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-02-23     Completed Date:  2011-06-09     Revised Date:  2014-09-15    
Medline Journal Info:
Nlm Unique ID:  9882735     Medline TA:  IEEE Trans Ultrason Ferroelectr Freq Control     Country:  United States    
Other Details:
Languages:  eng     Pagination:  305-15     Citation Subset:  IM    
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MeSH Terms
Ablation Techniques / instrumentation,  methods*
Analysis of Variance
Equipment Design
Erythrocytes / ultrasonography
Histological Techniques
Liver / pathology,  ultrasonography
Phantoms, Imaging
Ultrasonic Therapy / instrumentation,  methods*
Grant Support
R01 CA134579/CA/NCI NIH HHS; R01 CA134579/CA/NCI NIH HHS; R01 CA134579-03/CA/NCI NIH HHS; R01 DK087871/DK/NIDDK NIH HHS; R01 DK087871-01/DK/NIDDK NIH HHS; R01 EB008998/EB/NIBIB NIH HHS; R01 EB008998/EB/NIBIB NIH HHS; R01 EB008998-03/EB/NIBIB NIH HHS; R01 HL077629/HL/NHLBI NIH HHS; S10RR022425/RR/NCRR NIH HHS

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