Cross validation of Supersonic Shear Wave Imaging (SSI) with classical rheometry during blood coagulation over a very large bandwidth

Abstract

Deep venous thrombosis (DVT) affects millions of people worldwide. Its diagnosis and treatment depends on clot's age which is closely related to its viscoelastic properties. In this study we use Supersonic Shear Wave Imaging (SSI) and classical rheometry to measure the evolution of the viscoelastic properties of blood clots. Using SSI and shear wave spectroscopy (SWS), dispersion curves were obtained between 50 and 300 Hz every minute for 2 hours during coagulation. Using the values for G' and G" from the rheological studies, the theoretical shear wave speeds were calculated for frequencies between 0.25 and 30 Hz at the same time points. Maxwell, Voigt and Zener models were fitted to the dispersion data obtained by combining both techniques. Shear wave speed showed a marked increase with time of coagulation for all the frequencies, from around 0.5 m/s at the beginning of coagulation to 0.9 after 2 hours. The Zener model (μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , η) showed the best fit on the data out of the 3 models. Even though the Maxwell (μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</sub> , μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">η</sub> ) and Voigt (μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</sub> , η <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</sub> ) models did a good job at higher frequencies (70 Hz and up), both models failed to characterize the lower frequencies. Combination of SSI and classical rheometry allowed the characterization of the viscoelastic properties of blood clots in a very large frequency range between 0.25 Hz and 300 Hz. The two techniques showed very good agreement suggesting that SSI could be used to study the rheological properties of soft solids.