Diagnostic Ultrasound

Overview

Our diagnostic ultrasound research links hemodynamics and hemorheology to understand how red blood cells (RBCs) behave in large arteries under pulsatile flow, supporting the diagnosis and prognosis of cardiovascular and circulatory diseases.

Using a particle-based numerical model, we showed that erythrocyte aggregation under Womersley flow in an elastic vessel depends mainly on the axial shear rate: local aggregates form parabolic or M-shapes within a specific axial shear-rate range, while mean aggregation decreases with the radial shear rate (Lee et al., 2023). Building on this, we developed a 2D computational model that couples RBC dynamics with blood viscosity under pulsatile flow and combined it with whole-blood experiments using ultrasound B-mode imaging. This demonstrated that spatiotemporal variations of local hematocrit drive local variations of blood viscosity, with viscosity increasing in regions of elevated hematocrit during the acceleration phase of the pulsatile cycle (Lee & Paeng†, 2025).

Linking microscopic hemorheology (RBC aggregation and local hematocrit) with arterial hemodynamics: spatiotemporal RBC dynamics and local blood viscosity under pulsatile flow.

Research Fields

Numerical simulation of erythrocyte (RBC) aggregation under pulsatile (Womersley) flow
Axial shear rate as a hemorheological factor for local erythrocyte aggregation
Spatiotemporal blood viscosity from local hematocrit under pulsatile flow
Coupling whole-blood ultrasound B-mode imaging with computational hemodynamic modeling

References

2025

Diagnostic

Spatiotemporal blood viscosity by local hematocrit under pulsatile flow: Whole blood experiments and computational analysis

Cheong-Ah Lee and Dong-Guk Paeng^†

Computers in Biology and Medicine, Nov 2025

Abs DOI

Blood viscosity is inversely proportionate with shear rate mainly due to red blood cell (RBC) aggregation under steady flow. However, this inverse relation cannot explain the spatiotemporal variation of RBC dynamics under pulsatile flow. This study aimed to clarify the relationship between hemodynamics and hemorheology based on a novel computational model that couples RBC dynamics with blood viscosity under pulsatile flow. By integrating both whole-blood experiments with ultrasound imaging and numerical simulations, the spatiotemporal variations of local hematocrit were shown to drive local variations of blood viscosity under pulsatile flow. The results suggest that the local parabolic distribution of high hematocrit is influenced by RBC aggregation and pulsatile flow characteristics, which in turn affect blood viscosity. Computational analysis supports that local blood viscosity increased in regions with elevated hematocrit during the acceleration phase of pulsatile flow. Local hematocrit and RBC dynamics play critical roles in influencing blood viscosity under pulsatile flow, highlighting the importance of incorporating hemorheological and hemodynamic factors. These are crucial for understanding large arterial flow and potentially enhancing diagnostic and therapeutic approaches for cardiovascular diseases.

2023

Diagnostic

Axial shear rate: A hemorheological factor for erythrocyte aggregation under Womersley flow in an elastic vessel based on numerical simulation

Cheong-Ah Lee , Hafiz Muhammad Umer Farooqi, and Dong-Guk Paeng

Computers in Biology and Medicine, 2023

DOI