Blood flow velocity and wall shear stress estimation in forward-viewing intravascular ultrasound imaging: Comparison of Doppler and Particle Image Velocimetry (PIV) approaches

Author(s):  
Saeyoung Kim ◽  
Bowen Jing ◽  
Alessandro Veneziani ◽  
Brooks D. Lindsey
Author(s):  
L P Chua ◽  
W-F Ji ◽  
C M Yu ◽  
T-M Zhou ◽  
Y S Tan

This study was designed to examine the effects of the anastomotic angle on the flow and haemodynamic parameter distribution patterns of the proximal anastomoses, with emphasis on identifying site-specific haemodynamic features that could reasonably be expected to trigger the initiation and further development of anastomotic intimal hyperplasia. Particle image velocimetry measurements were carried out with three simplified glass proximal models under a physiological flow condition. The results revealed that the disturbed flow and the induced shear stress patterns including low recirculation flow, stagnation point, high wall shear stress, high temporal wall shear stress gradient, low time-averaged wall shear stress (TAWSS), and high oscillating shear index (OSI) occurred around the anastomotic joints and the flow field at proximal anastomosis was strongly affected by the anastomotic angle. Among the three models investigated, the 45° backward anastomosis is found to have a smaller low-recirculation-flow region along the graft inner wall, non-stationary stagnation, and separation points, a higher TAWSS and smaller high-OSI low-TAWSS and low-OSI high-TAWSS regions.


2011 ◽  
Vol 43 (Suppl 1) ◽  
pp. 743-744
Author(s):  
Kunihiko Aizawa ◽  
Phillip E. Gates ◽  
W David Strain ◽  
Oliver E. Gosling ◽  
Luciano Mazzaro ◽  
...  

2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Arati Gurung ◽  
Luciano Mazzaro ◽  
Philip E Gates ◽  
David Strain ◽  
Angela C Shore ◽  
...  

Wall shear stress (WSS) is an important modulator of vascular disease. We assessed the hypothesis that WSS profiles derived from Echo Particle Image Velocimetry (EchoPIV) are characteristic of vascular conditions such as TIA with superior accuracy to Doppler. We obtained ultrasound images of CCA from 24 healthy and 12 TIA subjects. Doppler provided centerline peak velocity and WSS estimate based on parabolic velocity distribution. Velocity profiles measured by EchoPIV varied from patient to patient and within the cardiac cycle. Curve-fitting to a power law function with an exponent term (n-value) showed that in healthy carotid arteries, a blunt velocity profile is present during systole with an average n-value of 5, whereas during diastole a more parabolic profile with an n-value of 2 is present. Therefore, assuming a fully parabolic velocity distribution for WSS estimation, the basis for Doppler velocimetry, introduces a mean error of 48% during diastole and 98% during systole. EchoPIV offers characterization of WSS profiles; time waveform analysis revealed smoother and fewer number of peaks per cycle for healthy and increased flow pulsatality (reverberations) for TIA (Figure). Echo PIV generated means for phase averaged peak velocity (27.95 vs 16.13 cm/s), WSS (6.45 vs 4.65 Dynes/cm2) and flow rate (0.3179 vs 0.2215 L/min) with standard deviations 3.66 vs 2.35, 2.8 vs 1.74 and 0.0723 vs 0.0744 were significantly different between healthy and TIA subjects respectively (all p < 0.01). Direct measurement of the velocity profile using Echo PIV provides superior estimates of WSS in carotid vessels. TIA populations have compromised hemodynamic variables compared to healthy subjects.


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