Abstract
Tumors with anisotropy in their structural properties experience unpredictable and asymmetric growth along certain directions that can vary over time during the tumor progression. An early recognition of such anisotropy could provide information about their malignity, facilitating early diagnostics/prognostic. However, it is difficult to be observed by classic echography. Diverse studies of the literature show 3D images of elastic properties in media with anisotropy in a certain direction, but are transversely isotropic. However, for highly anisotropy media this assumption is no longer valid and requires specific measurements of shear velocities in the 3D directions. These media with 21 independent elastic material parameters and no symmetry plane. Techniques using ultrafast focused sound scanners present difficulties in covering immediate regions around the focused area and specific information for different incident beam orientations to obtain complete 3D spatial information, which is relevant in these types of media without planes of symmetry. It is the case of malignant tumors. The current paper presents a flexible spatial study of mechanical displacements induced in highly anisotropic soft media by low frequency shaker (including printed inorganic, pseudo-organic grids and cow fiber tissues respectively). Homogeneous and heterogeneous media without planes of symmetry have been tested in the experiments by using speckle ultrasonic interferometry. Velocities associated to the induced low frequency-mechanical displacements have been analyzed at a point of interest within the sample from different angles of propagation, covering a 3D angular space. These measurements show a high spatial-dependence of results, demonstrating the relevance of making spatial angular scans to derive parameters related to the anisotropy. This technique allows detection of anisotropies in small areas of analysis, even if they are weak.
Highlights
Cancer is still one of the main causes of death in the world
This paper presents a flexible 3D spatial study of small volume dis placements in a region of interest generated by a low frequency pulse inside phantoms containing highly anisotropic soft media
These results obtained in the Control samples at a frequency f = 3.5 MHz are displayed in Fig. 4, showing a shear velocity of the elastic wave that remains almost constant at the two frequencies tested for any orientation of the ultrasonic beam (θ and φ angles), according to the isotropy of the sample
Summary
Cancer is still one of the main causes of death in the world (ancer 2018 and https://, 2018). It has been extensively studied, with signifi cant efforts made to understand the mechanisms regulating the tumor invasion by studying genetic and biochemical aspects (Herceg and Hainaut, 2007; Malandrino et al, 2018; Fares et al, 2020). Skerl et al found a certain correlation between anisotropy and tumor malignance in breast cancer by performing 2D shear wave elastography (SWE) measurements (Suhail et al, 2019). Chen et al analyzed in 2018 the anisotropy of ultrasound SWE of breast
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