Paper
12 April 2005 Vascular wall shear rate measurement using coded excitation techniques
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Abstract
Wall shear rate (WSR) is the derivative of blood velocity with respect to vessel radius at the endothelial surface. The product of WSR and blood viscosity is the wall shear stress (WSS) that must remain relatively high to maintain normal endothelial cell function, arterial health and prevent plaque formation. Accurate WSR estimation requires the lowest possible variance and bias for blood velocity estimates near the wall. This situation is achieved for conditions where the echo signal-to-noise ratio (eSNR) and spatial resolution for velocity are high. We transmitted coded pulses, i.e., those with time-bandwidth product greater than 1, to increase eSNR from weak blood scatter without increasing instantaneous power or reducing spatial resolution. This paper is a summary of WSR measurements from a flow phantom where a variety of acoustic pulses were transmitted: frequencymodulated (FM) codes and phase-modulated (PM) codes were compared with uncoded broadband and narrow band pulse transmissions. Both simulation and experimental results show that coded-pulse excitation increases accuracy and precision in WSR estimation when compared to standard pulsing techniques. Additionally, PM codes can reduce WSR errors more than FM codes for equal pulse energy. This reduction in WSR error could greatly extend the application of ultrasound in the study of cardiovascular disease.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jean K. Tsou, Jie Liu, and Michael F. Insana "Vascular wall shear rate measurement using coded excitation techniques", Proc. SPIE 5750, Medical Imaging 2005: Ultrasonic Imaging and Signal Processing, (12 April 2005); https://doi.org/10.1117/12.596100
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KEYWORDS
Phase modulation

Fermium

Frequency modulation

Blood

Spatial resolution

Error analysis

Transducers

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