Quantitative imaging performance of frequency-tunable capacitive micromachined ultrasonic transducer array designed...

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Materials Science

Background:

• Commercially available intracardiac echo (ICE) catheters present a compromise between imaging depth and resolution.
• Frequency-tunable ICE probes promise enhanced versatility by allowing selection between penetration or resolution imaging within a single device.

Purpose of the Study:

• To evaluate the imaging performance of a novel, frequency-tunable, 32-element, 1-D capacitive micromachined ultrasonic transducer (CMUT) array for intracardiac imaging.
• To demonstrate phased-array ultrasound imaging with a forward-looking CMUT probe prototype operating beyond collapse mode at high bias voltages.

Main Methods:

• A phantom study was conducted using a novel frequency-tunable CMUT array integrated with front-end electronics.
• Imaging performance was assessed by varying bias voltage (-70 V to -160 V), transmit pulse frequency (5-25 MHz), and pulse cycles (1-3).
• Phased-array ultrasound imaging was performed with the CMUT probe prototype, operating beyond its collapse voltage.

Main Results:

• The CMUT array demonstrated frequency tuning capabilities, enabling distinct imaging modes with adjustable resolution and penetration depth.
• Penetration mode achieved imaging up to 71 mm with 0.44 mm axial and 0.12 rad lateral resolution.
• Resolution mode yielded 0.055 mm axial and 0.035 rad lateral resolution with a penetration depth of 16 mm.

Conclusions:

• The frequency-tunable CMUT array shows potential for versatile intracardiac imaging, offering adjustable trade-offs between resolution and penetration depth.
• Despite a small transducer aperture (2 mm × 2 mm), the CMUT array exhibits promising characteristics for clinical intracardiac applications.