Fast Vascular Ultrasound Imaging With Enhanced Spatial Resolution and Background Rejection

Abstract

Abstract-Ultrasound super-localization microscopy techniques presented in the last few years enable non-invasive imaging of vascular structures at the capillary level by tracking the flow of ultrasound contrast agents (gas microbubbles). However, these techniques are currently limited by low temporal resolution and long acquisition times. Super-resolution optical fluctuation imaging (SOFI) is a fluorescence microscopy technique enabling sub-diffraction limit imaging with high temporal resolution by calculating high order statistics of the fluctuating optical signal. The aim of this work is to achieve fast acoustic imaging with enhanced resolution by applying the tools used in SOFI to contrast-enhance ultrasound (CEUS) plane-wave scans. The proposed method was tested using numerical simulations and evaluated using two in-vivo rabbit models: scans of healthy kidneys and VX-2 tumor xenografts. Improved spatial resolution was observed with a reduction of up to 50% in the full width half max of the point spread function. In addition, substantial reduction in the background level was achieved compared to standard mean amplitude persistence images, revealing small vascular structures within tumors. The scan duration of the proposed method is less than a second while current superlocalization techniques require acquisition duration of several minutes. As a result, the proposed technique may be used to obtain scans with enhanced spatial resolution and high temporal resolution, facilitating flow-dynamics monitoring. Our method can also be applied during a breath-hold, reducing the sensitivity to motion artifacts.

Bubble‐echo based deconvolution of contrast‐enhanced ultrasound imaging: Simulation and experimental validations

“…Taxt et al has compounded the deconvolution results of the first and second harmonic acoustic signal to acquire super‐resolution ultrasound images . Errico and Bar‐Zion et al have respectively applied the deconvolution based on Gaussian and system's PSF into super‐localization microscopy and super‐resolution optical fluctuation imaging to significantly improve the spatial resolution enhanced by microbubbles. Kuenen et al also used the Wiener deconvolution as a spatial filter to reduce the anisotropy and depth‐dependency of speckle‐grain size in CEUS .…”

Two stage sub-wavelength motion correction in human microvasculature for CEUS imaging

“…Researchers demonstrated the use of ultrasound superresolution imaging in many different controlled experiments and pre-clinical studies [3]- [9]. For the applications that are closer to a clinical imaging setup, researchers reported the problems caused by motion artefacts.…”

“…There are other methods based on localisation of spatially non-isolated microbubbles from a higher concentration. These methods can significantly reduce the acquisition duration; however they are still prone to motion artefacts at micrometre level [9], [10].…”

Localisation of multiple non-isolated microbubbles with frequency decomposition in super-resolution imaging

“…Bar-Zion et al proposed a model utilizing higher order statistics by acquiring less than a second of high frame rate ultrasound data. They achieved a modest improvement of 50% in spatial resolution with a significantly shorter acquisition time by localization of spatially non-isolated microbubbles [8]. Although this method is more practical, the final resolution of the super-resolution images is not as impressive as methods based on localizing spatially isolated microbubbles.…”