Simultaneous Axial Multifocal Imaging Using a Single Acoustical Transmission: A Practical Implementation

Asaf Ilovitsh, Tali Ilovitsh, Josquin Foiret, Douglas N. Stephens, Katherine W. Ferrara

Research output: Contribution to journalArticlepeer-review

Abstract

Standard ultrasound imaging techniques rely on sweeping a focused beam across a field of view; however, outside the transmission focal depth, image resolution and contrast are degraded. High-quality deep tissue in vivo imaging requires focusing the emitted field at multiple depths, yielding high-resolution and high-contrast ultrasound images but at the expense of a loss in frame rate. Recent developments in ultrasound technologies have led to user-programmable systems, which enable real-time dynamic control over the phase and apodization of each individual element in the imaging array. In this paper, we present a practical implementation of a method to achieve simultaneous axial multifoci using a single acoustical transmission. Our practical approach relies on the superposition of axial multifoci waveforms in a single transmission. The delay in transmission between different elements is set such that pulses constructively interfere at multiple focal depths. The proposed method achieves lateral resolution similar to successive focusing, but with an enhanced frame rate. The proposed method uses standard dynamic receive beamforming, identical to two-way focusing, and does not require additional postprocessing. Thus, the method can be implemented in real time on programmable ultrasound systems that allow different excitation signals for each element. The proposed method is described analytically and validated by laboratory experiments in phantoms and ex vivo biological samples.

Original languageEnglish
Article number8561216
Pages (from-to)273-284
Number of pages12
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Volume66
Issue number2
DOIs
StatePublished - Feb 2019
Externally publishedYes

Keywords

  • Beamforming
  • frame rate
  • multifoci
  • ultrasound imaging

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