Blood Characteristics Determine Vascular Risk

The university said that the study conducted by the researchers focused on the effect of this important property of blood on the safety of using contrast bubbles in ultrasound imaging.

Dr. Kevan Sadeghi, a faculty member at the College of Mechanics, explained that the research results showed that ignoring the true nature of blood and the previous assumption that it is a simple liquid leads to inaccurate estimates.

He added that advanced modeling in the study revealed that shear thinning can raise the shear stress on the blood vessel wall by up to 30%, and may also double the critical frequency of bubble vibration.

Sadeghi noted that encapsulated gas bubbles are increasingly used as contrast agents in ultrasound imaging, but the main challenge is the shear stress that the blood vessel lining may be exposed to during the bubble’s vibration, which may lead to Cell damage Indotile.

According to the researchers, previous studies assumed that blood was a Newtonian fluid, but the new study used the Carro rheological model to accurately simulate the effect of shear thinning on the shear stress in the vessel wall.

The study stated that the simulation was restricted to small vibrations to ensure that the bubble remained nearly spherical, while the Dejong model was used to calculate the radius of the bubble moment by moment, based on a viscoelastic Kelvin-Vogt shell. The study also adopted a model that describes the mutual interaction between the bubble and the blood vessel by solving the equations of movement of the fluid separating them.

According to the results, it is expected that shear thinning behavior will raise the maximum shear stress in the blood vessel by approximately 30%, in addition to doubling the frequency associated with this stress.

The results also indicate that this behavior produces velocity profiles containing inflection points, making the flow susceptible to hydrodynamic instability, while the parametric analysis shows that the time constant in the Caro model plays a crucial role in determining the flow dynamics during bubble oscillations.

The researchers emphasized that the basic conclusion of the study is the necessity of taking into account the real rheological behavior of blood in medical applications that use contrast bubbles, to ensure the accuracy of the evaluation and raise the level of safety in imaging techniques.