Methodology on Quantification of Sonication Duration for Safe Application of MR Guided Focused Ultrasound for Liver Tumour Ablation

Senay Mihcin (Lead / Corresponding author), Ioannis Karakitsios, Nhan Le, Jan Strehlow, Daniel Demedts, Michael Schwenke, Sabrina Haase, Tobias Preusser, Andreas Melzer

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    Abstract

    Background and Objective: Magnetic Resonance Guided Focused Ultrasound (MRgFUS) for liver tumour ablation is a challenging task due to motion caused by breathing and occlusion due the ribcage between the transducer and the tumour. To overcome these challenges, a novel system for liver tumour ablation during free breathing has been designed.

    Methods: The novel TRANSFUSIMO Treatment System (TTS, EUFP7) interacts with a Magnetic Resonance (MR) Scanner and a focused ultrasound transducer to sonicate to a moving target in liver. To meet the requirements of ISO 13485; a quality management system for medical device design, the system needs to be tested for certain process parameters. The duration of sonication and, the delay after the sonication button is activated, are among the parameters that need to be quantified for efficient and safe ablation of tumour tissue. A novel methodology is developed to quantify these process parameters. A computerised scope is programmed in LabVIEW to collect data via hydrophone; where the coordinates of fiber-optic sensor assembly was fed into the TRANSFUSIMO treatment software via Magnetic Resonance Imaging (MRI) to sonicate to the tip of the sensor, which is synchronised with the clock of the scope, embedded in a degassed water tank via sensor assembly holder. The sonications were executed for 50W, 100W, 150W for 10 seconds to quantify the actual sonication duration and the delay after the emergency stop by two independent operators for thirty times. The deviation of the system from the predefined specs was calculated. Student’s-t test was used to investigate the user dependency.

    Results: The duration of sonication and the delay after the sonication were quantified successfully with the developed method. TTS can sonicate with a maximum deviation of 0.16s (Std 0.32) from the planned duration and with a delay of 14ms (Std 0.14) for the emergency stop. Student’s T tests indicate that the results do not depend on operators (p>0.05).

    Conclusion: The evidence obtained via this protocol is crucial for translation- of-research into the clinics for safe application of MRgFUS. The developed protocol could be used for system maintenance in compliance with quality systems in clinics for daily quality assurance routines.
    Original languageEnglish
    Pages (from-to)125-130
    Number of pages6
    JournalComputer Methods and Programs in Biomedicine
    Volume152
    Early online date20 Sep 2017
    DOIs
    Publication statusPublished - 1 Dec 2017

    Keywords

    • MR guided FUS
    • Computer control of laboratory machnies and device
    • Safety
    • Protocol Development
    • Quality Management Systems
    • Experiment and Measurement Technics
    • Medical Device Legislation
    • Sonication duration

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