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.
Original language | English (US) |
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Article number | 30 |
Pages (from-to) | 269-280 |
Number of pages | 12 |
Journal | Progress in Biomedical Optics and Imaging - Proceedings of SPIE |
Volume | 5750 |
DOIs | |
State | Published - 2005 |
Externally published | Yes |
Event | Medical Imaging 2005 - Ultrasonic Imaging and Signal Processing - San Diego, CA, United States Duration: Feb 15 2005 → Feb 17 2005 |
Keywords
- Bias and variance
- Blood velocity estimation
- Coded excitation
- Wall shear rate
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Radiology Nuclear Medicine and imaging
- Biomaterials