Estimating vascular volume fraction in a network of small blood vessels with high-frequency power Doppler ultrasound.
Quantitative images of high-frequency (> 20 MHz) power Doppler ultrasound can be difficult to obtain in the presence of flow artifacts due to power Doppler's sensitivity to operator-dependent acquisition settings. To improve flow quantification, color pixel density (CPD) can be plotted as a function of wall filter cut-off velocity to produce a wall-filter selection curve that can be used to estimate vascular volume fraction by locating the plateau along the curve. The behavior of the wall-filter selection curve in a multiple-vessel region of interest is studied using a custom-designed multiple-vessel flow phantom. The flow phantom is capable of mimicking a range of blood vessel sizes (200-300 microm), blood flow velocities (1-10 mm/s), and blood vessel orientations (long-axis and transverse). At high flow rates, single-vessel wall-filter selection curves superimpose to produce a multiple-vessel curve where the CPD at the left-most plateau corresponds with the actual vascular volume fraction. However, interpretation of the multiple-vessel wall-filter selection curve is not straightforward when the flow rate in the vascular network is low.
Pinter
Stephen Z
SZ
Biomedical Engineering Graduate Program and Robarts Research Institute, University of Western Ontario, London, Ontario, Canada. spinter@ieee.org
Lacefield
James C
JC
D000818:Animals; D001698:Biomedical Engineering / Q000379:methods; D001783:Blood Flow Velocity; D001808:Blood Vessels / Q000000981:diagnostic imaging*; D001810:Blood Volume; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted; D051379:Mice; D055806:Microvessels / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D012372:ROC Curve; D012815:Signal Processing, Computer-Assisted; D018615:Ultrasonography, Doppler, Color / Q000295:instrumentation* / Q000379:methods