Focusing through the rib cage for MR-guided transcostal FUS

J. Gao, A. Volovick, Y. Pekelny, Z. Huang, S. Cochran, A. Melzer

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    3 Citations (Scopus)


    The rib cage presents a significant obstacle in transcostal focused ultrasound surgery (FUS). This paper proposes a geometric solution, based on central projection from the focus to identify transducer elements affected by ribs shadowing which should be switched off. Its effectiveness in phantom experiments and simulations is reported, and ways are discussed to further reduce energy deposition on the ribs while enhancing heating at the focus. A tissue-mimicking phantom with phantom of ribs was sonicated using a 208-element 1.15 MHz bowl transducer and a 1000-element 550 kHz planar matrix transducer (both ExAblate, InSightec, Israel). The temperature evolution was monitored with real-time MRI thermometry (GE, USA). Numerical simulations were performed with FEA software (PZFlex, Weidlinger Associates, USA) to investigate different skin-focus and transducer-rib distances. The temperature rise near the ribs was reduced to 16 degrees C and 4 degrees C for the 1.15 MHz and 550 kHz transducers respectively. With the 1.15 MHz transducer, the focal temperature reached the ablation threshold. These measurements are in good agreement with simulations. The proposed method shows promising results for transcostal FUS. Residual temperature rise on the ribs can be further reduced by active cooling, allowing the higher energies essential for efficient ablation.

    Original languageEnglish
    Title of host publication11th International Symposium on Therapeutic Ultrasound
    EditorsRobert Muratore, Elisa E. Konofagou
    Place of PublicationMelville
    PublisherAmerican Institute of Physics
    Number of pages6
    ISBN (Print)9780735410930
    Publication statusPublished - 2012
    Event11th International Symposium on Therapeutic Ultrasound - Marriott Marquis, New York, United States
    Duration: 11 Apr 201113 Apr 2011

    Publication series

    NameAIP conference proceedings
    PublisherAmerican Institute of Physics
    ISSN (Print)0094-243X


    Conference11th International Symposium on Therapeutic Ultrasound
    Country/TerritoryUnited States
    CityNew York


    • Geometric ribs sparing method
    • MR-guided Transcostal FUS
    • LIVER


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