3-D Super-Resolution Ultrasound Imaging With a 2-D Sparse Array

Abstract

High frame rate 3-D ultrasound imaging technology combined with super-resolution processing method can visualize 3-D microvascular structures by overcoming the diffraction limited resolution in every spatial direction. However, 3-D superresolution ultrasound imaging using a full 2-D array requires a system with large number of independent channels, the design of which might be impractical due to the high cost, complexity, and volume of data produced.In this study, a 2-D sparse array was designed and fabricated with 512 elements chosen from a density-tapered 2-D spiral layout. High frame rate volumetric imaging was performed using two synchronized ULA-OP 256 research scanners. Volumetric images were constructed by coherently compounding 9-angle plane waves acquired in 3 milliseconds at a pulse repetition frequency of 3000 Hz. To allow microbubbles sufficient time to move between consequent compounded volumetric frames, a 7millisecond delay was introduced after each volume acquisition. This reduced the effective volume acquisition speed to 100 Hz and the total acquired data size by 3.3-fold. Localization-based 3-D super-resolution images of two touching sub-wavelength tubes were generated from 6000 volumes acquired in 60 seconds. In conclusion, this work demonstrates the feasibility of 3D superresolution imaging and super-resolved velocity mapping using a customized 2D sparse array transducer.

3-D Super Resolution Imaging using a 62+62 Elements Row-Column Array

“…The major advantage is that the volume is focused in all three directions including the elevation direction, which yields a resolution of (1.17λ × 2.12λ × 0.63λ ) at a depth of 15 mm. This was attained for a modest 62 elements, which both reduces the amount of data from the probe by a factor of 8 compared to previous 3-D SRI [13] as well as the beamforming time for a probe with 4 times the area of a 1024 elements 2-D matrix probe. Points outside in y-z plane Fig.…”

Functional ultrasound speckle decorrelation-based velocimetry of the brain

“…In the future, with the development of fast 3D ultrasound imaging technology using a 2D transducer matrix 32 , vUS can be easily adopted for 3D velocimetry of the whole rodent brain. In addition, in combination with oxygenation measurements using multispectral photoacoustic tomography (mPAT) and given the blood flow (velocity) measured by vUS, the direct biomarker indicating neuron activity, i.e., the metabolic rate of oxygen, can be readily measured, which will greatly facilitate neuroscience research.…”

Super-resolution Ultrasound Imaging

“…In vivo, this apparatus was able to reconstruct entire super-resolved volumes of the rat brain, alleviating the previously described drawbacks with 3-D tracking and motion correction. Harput et al (2019b) reduced the number of connected channels by implementing super-resolution on a 2-D sparse array. 3-D super-resolution could even be performed with a clinical scanner as described by Christensen-Jeffries et al (2018).…”

“…In the past decade it has been well reported that the vaporization of such phase-change nanodroplets into microbubbles can be controlled by acoustic pressure (Sheeran et al 2012). This phase transition also depends on nanodroplet characteristics (e.g., size distribution and boiling point of the gas) and external factors (e.g., microvessel confinement [Lin et al 2018] and attachment to cells [Zhang et al 2019b]).…”

“…However, motion that occurs orthogonal to the image plane remains a challenge. In this context, advancing CEUS imaging from 2-D to true 3-D using matrix transducers, which has been done in vitro (Harput et al 2019a;Heiles et al 2019), may not only allow display of the vascular network in much greater comprehensiveness and detail, but also holds promise for a precise motion correction in all directions (Harput et al 2019b).…”