We present a physically intuitive matrix approach for quantitative imaging of complex media. While standard reflection imaging methods generally rely on confocal focusing operations, matrix imaging consists of decoupling the location of the incident and received focal spots [1]. Following this principle, a self-portrait of the focusing process can be obtained around each point of the medium. The Gouy phase shift exhibited by each focal spot can be leveraged to finely monitor the wave velocity distribution inside the medium [2]. A local multiple scattering rate can also be evaluated and its depth evolution can lead to a local measurement of the scattering mean free path, independently from absorption losses [3]. The approach is here demonstrated with ultrasound for a controllable phantom system before being applied in vivo to liver. The wave velocity and the scattering mean free path are quantitative markers for biomedical diagnosis but they are also important monitoring parameters for nondestructive testing and geophysical applications. This work thus opens important perspectives for quantitative imaging of heterogeneous media in all fields of acoustics. [1] W. Lambert etal., Phys. Rev. X 10, 021048 (2020). [2] F. Bureau et al., arXiv:2409.13901 (2024). [3] A. Goicoechea et al., Phys. Rev. Lett. 133, 176301 (2024).
In the last decade, multimodal imaging raised increasing interest to overcome the limits of single techniques and improve the diagnostic potential during the same examination. This gives rise to the need for phantoms and procedures for standardizing performance assessment of the multimodal instrument. The SOLUS1 project adopts this methodology with the aim to build a multimodal instrument (based on diffuse optics -DO-, shear wave elastography -SWE-, and ultrasound imaging -US-) to increase the specificity of breast cancer diagnosis. Here we propose a long-lasting phantom based on silicone material (easier to manipulate with respect to other material for bimodal phantom such as polyvinyl alcohol, PVA) and suitable for both diffuse optical imaging/tomography and ultrasound acquisitions, designed within the SOLUS project. To achieve this goal, we explored a new silicone material for diffuse optics and ultrasound (Ecoflex 00-30), creating a new fabrication recipe and demonstrating its suitability for multimodal imaging if coupled to another silicone elastomer (Sylgard 184), featuring similar optical and acoustical performances except for the echogenicity. The main advantage of the proposed phantom is the capability of tuning independently optical and acoustical performances, thus allowing one to mimic a wide range of clinical scenarios.
Overcoming the resistant to change - is there a strategy that could bring all the different stakeholders to combine and align efforts?
