title: In vivo imaging of ocular blood flow using high-speed ultrasound.
abstract: Clinical ophthalmic ultrasound is currently performed with mechanically scanned, single-element probes, but these are unable to provide useful information about blood flow with Doppler techniques. Linear arrays are well-suited for the detection of blood flow, but commercial systems generally exceed FDA ophthalmic safety limits. A high-speed plane-wave ultrasound approach with an 18-MHz linear array was utilized to characterize blood flow in the orbit and choroid. Acoustic intensity was measured and the plane-wave mode was within FDA limits. Data were acquired for up to 2 sec and up to 20,000 frames/s with sets of steered plane-wave transmissions that spanned 2*θdegrees where 0 degrees was normal to the array. Lateral resolution was characterized using compounding from 1 to 50 transmissions and -6-dB lateral beamwidths ranged from 320 to 180μm, respectively. Compounded high-frame-rate data were post-processed using a singular value decomposition spatiotemporal filter and then flow was estimated at each pixel using standard Doppler processing methods. A 1-cm diameter rotating scattering phantom and a 2-mm diameter tube with a flow of blood-mimicking fluid were utilized to validate the flow-estimation algorithms.In vivodata were obtained from the posterior pole of the human eye which revealed regions of flow in the choroid and major orbital vessels supplying the eye.
authors.affiliation: Lizzi Center for Biomedical Engineering, Riverside Research, New York, NY.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Ketterling
authors.affiliation: Department of Ophthalmology, Harkness Eye Institute, Columbia University Medical Center, New York, NY.
authors.forename: Raksha
authors.initials: R
authors.lastname: Urs
authors.affiliation: Department of Ophthalmology, Harkness Eye Institute, Columbia University Medical Center, New York, NY.
authors.forename: Ronald H
authors.initials: RH
authors.lastname: Silverman