High-frequency power Doppler imaging of angiogenesis can be challenging given the presence of small blood
vessels and slow flow velocities. In the presence of substantial Doppler artifacts such as false-positive color
pixels or undetected vessels, color pixel density (CPD) and related vascularity metrics do not provide accurate
estimates of vascular volume fraction. As a step towards improved microvascular quantification, flow-phantom
experiments were performed to establish relationships between CPD and wall filter cut-off velocity for various
combinations of vessel size (160, 200, 250, 300, and 360 μm), flow velocity (4, 3, 2, 1, and 0.5 mm/s), and
transducer frequency (30 and 40 MHz). Three distinct regions were observed in plots of CPD versus wall filter
cut-off velocity: overestimation of CPD at low cut-offs, underestimation of CPD at high cut-offs, and a plateau
at intermediate cut-offs. The CPD at the plateau closely matched the phantom's actual vascular volume fraction.
The length of the plateau corresponded with the flow-detection performance of the Doppler system, which was assessed using receiver operating characteristic analysis. Color pixel density versus wall filter cut-off curves from analogous in vivo experiments exhibited the same shape, including a distinct CPD plateau. The similar shape of the flow-phantom and in vivo curves suggests that the presence of a plateau can be used to identify the best-estimate CPD value in an in vivo experiment. The ability to identify the best CPD estimate is expected to improve quantification of angiogenesis and anti-angiogenic treatment responses with power Doppler.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.