Sonorheometry: A new method for assessing coagulation potential

Inappropriate blood coagulation is a significant contributing factor in the onset of potentially fatal thrombotic events such as myocardial infarction, stroke, deep vein thrombosis (DVT), and pulmonary embolism (PE). The ability to recognize and quantify thrombotic disorders is thus critical to implement appropriate treatment. We have developed a novel technique, called sonorheometry, which can identify an increased or decreased propensity to clot by observing the coagulation rate and mechanical characteristics of the developing clot. Sonorheometry utilizes acoustic radiation force with ultrasound motion tracking. We have designed and fabricated a sonorheometry system which is controlled by an external laptop computer. In the experiments presented in this paper, we analyzed blood samples of lml using a 10MHz, fixed focus transducer at a PRF of 400Hz. Measurements were performed every 6 sec for 7 min after blood was drawn. Returning echoes were processed using a spline-based tracking method to determine the time dependent deformations induced by the application of the force. These deformations were modeled using two Voigt models in series with added inertia to generate data depicting various mechanical properties. We present time displacement curves that show maximum displacements of 40μm; detectable displacements decrease as the blood clots. We also show the viscoelastic parameters obtained from the model. These results show that sonorheometry could be used to assess coagulation potential.