A new ultrasonic transducer for improved contrast nonlinear imaging

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Ultrasound Technology

Background:

• Second harmonic imaging offers improved contrast detection over fundamental imaging due to higher contrast-to-tissue ratio (CTR).
• However, differentiating contrast agents from tissue at second harmonic frequencies remains challenging, particularly in capillaries, due to nonlinear propagation effects in tissue obscuring contrast echoes.
• Theoretical studies suggest CTR increases with harmonic number.

Purpose of the Study:

• To enhance contrast detection by selectively imaging higher harmonic frequencies (third to fifth).
• To develop a novel ultrasonic phased array transducer capable of receiving these high-frequency components.

Main Methods:

• Designed and fabricated a new ultrasonic phased array transducer with a wide frequency bandwidth.
• The transducer features interleaved odd (2.8 MHz, 80% bandwidth) and even (900 kHz, 50% bandwidth) elements for separate transmission and reception.
• Connected the probe to a Vivid 5 system and developed custom software for operation.

Main Results:

• The transducer achieved a total bandwidth exceeding 150%, enabling higher harmonic imaging.
• Demonstrated adequate sensitivity and signal-to-noise ratio compared to standard transducers.
• Preliminary in vitro and in vivo evaluations showed advantages for nonlinear contrast imaging.

Conclusions:

• The developed wide-bandwidth phased array transducer facilitates improved higher harmonic imaging.
• This technology offers enhanced contrast detection capabilities, addressing limitations of current second harmonic imaging.
• The design shows promise for advancing nonlinear contrast imaging in medical ultrasound.