Tendon Phantom Mechanical Properties Assessment by Supersonic Shear Imaging with Three-Dimensional Transducer

Phantom mimics biological tissues properties, i.e., acoustic and mechanical. Tendon connects muscle to bone and allows joint motion. To evaluate tendon mechanical properties, i.e. Young modulus, in vitro and in vivo studies were developed. In the 90s, Elastography emerged as a promise tool to tissue mechanical properties assessment, i.e., breast and liver. Recently, Supersonic Shear Imaging (SSI) technique was developed to calculate quantitative Elastic modulus (E) from transversal shear wave propagation velocity (C_S). The most recent 3D transducer can provide a tridimensional visualization of an organ (sagittal, transverse and coronal). The aim of this study is to assess transverse shear wave propagation velocity (C_S) on tendon phantom using SSI with 3D transducer. This tendon phantom was composed basically PVCP plastisol® and glycerin (15%). For image acquisition, the Aixplorer v.11 equipment (Supersonic Imagine, Aix-en-Provence, France) with 3D transducer (Super linear TM volumetric SLV 16–5, 5–16 MHz) were used. The 3D transducer was placed randomly at the phantom surface and three images were acquired. Each one presented the three orthogonal planes (sagittal, transverse and coronal) and the respective intersection points between two other planes. For each plane, a 5.0 mm ROI (Region of Interest) was positioned around the intersection point to measure C_S. The mean C_S values were 6.2 m/s (+0.3), 6.4 m/s (+0.4) and 6.3 m/s (+0.3) for sagittal, transverse and coronal planes, respectively. These results were different to the only study which evaluated an anisotropic phantom tendon with SSI. However, when compared to previous studies, the results were similar to human healthy patellar tendon. This is a whole homogeneous phantom and it was not possible to mimic the oriented fibers presented on the tendon. Future studies should be performed with anisotropic phantoms to standardize the validation of elastography techniques dedicated to healthy and pathological tissues.