Quantitative ultrasound by high-frame-rate blood characterization

Quantitative ultrasound of blood enables noninvasive characterization of erythrocyte aggregation and disaggregation, which are closely linked to inflammation. To preserve depth of field and enable continuous shear stress-dependent measurements, we utilize high-frame-rate imaging at several 10 MHz rather than high-frequency ultrasound (20 MHz). However, conventional single-frequency excitation around 10 MHz suffers from limited bandwidth and low signal-to-noise ratio (SNR), reducing the accuracy of backscatter coefficient (BSC) analysis. To overcome this, we propose a dual-frequency excitation method alternating between 7.8 and 12.5 MHz using long burst waves. In vivo experiments on forearm veins of healthy subjects demonstrated that this method improves SNR by 10 dB and bandwidth by 130%, yielding more stable and distinct BSC estimates. Parametric imaging revealed clearer changes in erythrocyte aggregate size before and after vascular occlusion. Our current focus is on applying this technique to forearm arteries to quantify blood property changes during flow-mediated dilation (FMD), aiming to evaluate endothelial function and wall shear stress. This presentation introduces our ongoing research and its potential for clinical application in FMD.