On the Impact of Microbeamformers in 3-D High Frame Rate Ultrasound Imaging: A Simulation Study

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Biomedical Engineering

Background:

• Three-dimensional ultrasound imaging utilizes 2D arrays and microbeamformers (µB) to reduce channel counts, typically for line-by-line focused beam (FB) sequences.
• High frame rate (HFR) imaging, using defocused beams, is crucial for detailed tissue and blood motion analysis.
• Limited research exists on the impact of µB on image quality within HFR ultrasound applications.

Purpose of the Study:

• To evaluate the influence of microbeamformers (µB) on image quality in high frame rate (HFR) transthoracic echocardiography.
• To assess the impact of varying µB sub-array sizes on image resolution and contrast.
• To compare different scan sequences (FB, FWB, PDW) in the presence of a µB.

Main Methods:

• Simulated multi-plane HFR transthoracic echocardiography with µB integrated into 2D probes.
• Tested µB connected to sub-arrays ranging from 2x2 to 8x8 elements.
• Reconstructed B-Mode images using focused beams (FB), focused wide beams (FWB), and planar diverging waves (PDW), comparing to an ideal case without µB.

Main Results:

• Microbeamformer presence caused resolution and contrast deterioration up to 17.5% and -26 dB, respectively, compared to the ideal scenario.
• The most significant degradation occurred during the transmission of widest planar diverging waves (PDW).
• Synthetic transmit beam techniques showed potential for partial recovery of image quality.

Conclusions:

• Microbeamformers designed for FB imaging can be employed in HFR applications, but result in reduced image quality.
• Guidelines are provided to balance image quality, µB size, channel count, and frame rate for HFR ultrasound.
• This study highlights the trade-offs associated with using µB in HFR echocardiography.