An Ultrasonic-Adaptive Beamforming Method and Its Application for Trans-skull Imaging of Certain Types of Head Injuries; Part I: Transmission Mode

Abstract

A new adaptive beamforming algorithm for imaging via small-aperture 1-D ultrasonic-phased arrays through composite layered structures is reported. Such structures cause acoustic phase aberration and wave refraction at undulating interfaces and can lead to significant distortion of an ultrasonic field pattern produced by conventional beamforming techniques. This distortion takes the form of defocusing the ultrasonic field transmitted through the barrier and causes loss of resolution and overall degradation of image quality. To compensate for the phase aberration and the refractional effects, we developed and examined an adaptive beamforming algorithm for small-aperture linear-phased arrays. After accurately assessing the barrier's local geometry and sound speed, the method calculates a new timing scheme to refocus the distorted beam at its original location. As a tentative application, implementation of this method for trans-skull imaging of certain types of head injuries through human skull is discussed. Simulation and laboratory results of applying the method on skull-mimicking phantoms are presented. Correction of up to 2.5 cm focal point displacement at up to 10 cm depth under our skull phantom is demonstrated. Quantitative assessment of the method in a variety of temporal focusing scenarios is also reported. Overall temporal deviation on the order of a few nanoseconds was observed between the simulated and experimental results. The single-point adaptive focusing results demonstrate strong potential of our approach for diagnostic imaging through intact human skull. The algorithms were implemented on an ultrasound advanced open-platform controlling 64 active elements on a 128-element phased array.

Observation of Guided Acoustic Waves in a Human Skull

“…Observation and characterization of the skull-guided waves can be used for a more accurate interpretation of transcranial image data, such as optoacoustic images that are often afflicted by the complex wave propagation in the skull manifested via distortions in the location and shape of the vascular structures [13]. Our results may thus contribute to the development and optimization of non-invasive ultrasound-based techniques for diagnostic brain imaging [10,[21][22][23]32], monitoring of neural activity [24,25], guided surgery applications [33], or cranial bone assesment without the use of ionizing radiation [18].…”

“…In addition to transcranial ultrasonography [21][22][23], new ultrasound-mediated techniques are currently being proposed [24,25] to monitor neural activity in cortical areas of the human brain transcranially. It is thus desirable to extend the current knowledge about the near-field ultrasound wave propagation of the human skull.…”

Ultrasound Phantom Using Sodium Alginate as a Gelling Agent

“…These phantoms can be easily made to simulate real anatomic structures by using 3‐dimensional printing technologies, and the properties of the phantoms can be also modified to suit the user's request. Phantoms made with this technology are still expensive, but future development of this technology is expected …”

“…Phantoms made with this technology are still expensive, but future development of this technology is expected. [41][42][43] In summary, we propose a laboratory-made ultrasound phantom using sodium alginate as a gelling agent.…”

Phase Aberration Robust Beamformer for Planewave US Using Self-Supervised Learning

“…Unfortunately, most of the aforementioned phase aberration correction methods are based on simulation or modelbased studies which often require stringent alignment between assumed and real measurement conditions. Furthermore the methods are based on iterative/trial-based optimization principals which are computational expensive and unsuitable for real-time ultra fast ultrasound imaging [14], [24]. Moreover, these approaches are mainly designed for focused B-mode imaging.…”