A nonparametric temperature controller with nonlinear negative reaction for multi-point rapid MR-guided HIFU...

Area of Science:

• Oncology
• Medical Imaging
• Ultrasound Technology

Background:

• Magnetic resonance-guided high intensity focused ultrasound (MRgHIFU) offers noninvasive thermal ablation.
• Accurate visualization and real-time thermometry via MRI are crucial for effective ablation.
• Achieving oncological quality requires precise volumetric sonication with feedback control.

Purpose of the Study:

• To develop and evaluate a novel nonparametric temperature controller for volumetric MRgHIFU.
• To ensure a consistent thermal history at each sonication point during treatment.
• To investigate the efficacy of the controller across different sonication patterns.

Main Methods:

• A nonparametric, nonlinear negative reaction temperature controller was designed.
• Iterated sonication of prescribed focal patterns was performed using a phased-array HIFU transducer.
• Ex vivo and in vivo experiments utilized a 3T MRI scanner for simultaneous temperature measurement across multiple slices.

Main Results:

• In vivo studies demonstrated a similar thermal history across sonicated foci (17.3 ± 0.5 °C elevation vs. 16 °C target).
• The controller enabled precise spatio-temporal temperature control.
• Analysis allowed for comparison of sonication patterns regarding dosimetry and safety.

Conclusions:

• The developed controller effectively achieves consistent thermal history in volumetric MRgHIFU.
• This technology enhances the precision and safety of noninvasive thermal ablation for oncological applications.
• Further investigation into sonication patterns revealed potential downward drift in thermal build-up with circular scans.