Pulse compression technique for simultaneous HIFU surgery and ultrasonic imaging: a preliminary study

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Surgical Guidance

Background:

• Simultaneous imaging and therapy in High Intensity Focused Ultrasound (HIFU) surgery requires suppressing reflected HIFU waves.
• Interference from HIFU waves degrades the quality of real-time ultrasound imaging.

Purpose of the Study:

• To investigate the feasibility of a pulse compression scheme combined with notch filtering to minimize HIFU interference signals.
• To enable real-time ultrasound image-guided HIFU surgery.

Main Methods:

• Utilized a chirp signal (3-9MHz) for B-mode imaging and a 4MHz continuous wave for HIFU.
• Employed second-order infinite impulse response notch filters (4MHz and 8MHz) to suppress HIFU waves.
• Fabricated a prototype integrated HIFU/imaging transducer with a center imaging element and outer HIFU transmitting elements.

Main Results:

• The pulse compression and notch filtering significantly reduced HIFU interference waves while preserving the imaging signal.
• Reduced reflected HIFU wave amplitude by -45dB in a single scanline test.
• Restored B-mode images in in vitro tests showed speckle patterns similar to the original image.

Conclusions:

• The pulse compression scheme with notch filtering shows potential for effective HIFU interference reduction.
• This technique can significantly improve real-time imaging quality in image-guided HIFU surgery.
• Preliminary results support the viability of this approach for clinical application.