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Suzanne Daly, Raksha Urs, Harriet O Lloyd, D Jackson Coleman, Ronald H Silverman; Visualization of Anterior Segment Blood Flow with Plane-Wave Ultrasound. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1693.
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© 2017 Association for Research in Vision and Ophthalmology.
Blood flow in the microvasculature of the anterior segment (iris, ciliary body) and larger vessels such as the major arterial circle at the iris root and the ciliary arteries is difficult or impossible to visualize optically or ultrasonically due to slow flow velocities, inadequate resolution, ‘clutter’ (light or acoustic scattering from tissue structures) and motion artifacts. In this report we describe visualization of blood flow in the anterior segment using ultra-high-speed compound coherent plane-wave ultrasound methods.
We imaged the anterior segment of a normal human subject at acoustic intensities compliant with FDA regulations using a 20 MHz linear array probe and a user-programmable research ultrasound platform (Verasonics Vantage 128). The probe had 128 elements and a focal depth in the elevation axis of 7 mm. Using an immersion technique, we placed the probe such that anterior segment structures of interest were in the focal plane. We acquired phase-resolved plane wave data at a series of 7 angles over a 36-degree range. Real-time vector Doppler data were acquired at a 2 kHz frame-rate interleaving for B-mode data with groups of 14 narrowband plane-wave frames emitted at one angle for depiction of color-flow . Slow-flow was imaged by post-processing of data accumulated over 2 seconds a 2 kHz frame rate.
Vector Doppler allowed real-time visualization of blood-flow vessels such as the major arterial circle and long posterior ciliary arteries. Plane-wave Doppler visualized flow in the iris and ciliary body as well as in the major vessels. Post-processed data allowed visualization of changes in flow over the cardiac cycle.
Visualization and measurement of blood flow in the anterior segment, as demonstrated in this feasibility study, will introduce a new and important capability for assessment of conditions such as uveitis, anterior segment neoplasms and assessment of medication effects in glaucoma.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
20 MHz vector Doppler color-flow image of anterior segment obtained in real time.
Plane-wave color-flow image of anterior segment depicting slow-flow in ciliary body and iris.
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