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. 2010 May;248(5):675-80.
doi: 10.1007/s00417-009-1298-9. Epub 2010 Feb 17.

Ultrasonic Doppler measurements of blood flow velocity of rabbit retinal vessels using a 45-MHz needle transducer

Naoki Matsuoka  1 , Dong-Guk Paeng, Ruimin Chen, Hossein Ameri, Walid Abdallah, Qifa Zhou, Amani Fawzi, K K Shung, Mark Humayun
Affiliations

Ultrasonic Doppler measurements of blood flow velocity of rabbit retinal vessels using a 45-MHz needle transducer

Naoki Matsuoka et al. Graefes Arch Clin Exp Ophthalmol. 2010 May.

Abstract

Background: The purpose of this study is to measure blood flow velocity of rabbit retinal vessels using a 45-MHz ultrasonic Doppler system with a needle transducer.

Methods: A high-frequency pulsed Doppler system that utilizes a 45-MHz PMN-PT needle transducer was developed to measure retinal blood flow velocity in situ. The pulsed Doppler allowed the differentiation of retinal from choroidal blood flow velocity. The needle transducer was inserted into the vitreous cavity through a 20-gauge incision port to access the retinal vessels. The first phase of the experiment evaluated the reproducibility of the measurements. The second phase measured velocities at four positions from the optic disc edge to the distal part of each vessel in nine eyes for the temporal and six eyes for the nasal portions. The angle between the transducer and the retinal vessel at each site was measured in enucleated rabbit eyes to estimate and compensate for measurement errors.

Results: In the first phase, the average measurement error was 5.97 +/- 1.34%. There was no significant difference comparing all eyes. In the second phase, the velocities gradually slowed from the disc edge to the distal part, and temporal velocities were faster than nasal velocities at all measurement sites.

Conclusion: This study demonstrated the feasibility of reliably measuring retinal blood flow velocity using a 45-MHz ultrasonic Doppler system with a needle transducer.

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Figures

Fig. 1
Fig. 1
A photograph of PMN-PT needle transducers
Fig. 2
Fig. 2
Typical radio frequency signal with time gate windows of the Doppler measurements for retinal vessels (a) and choroid vessels (b)
Fig. 3
Fig. 3
A representative image, showing the intraocular ultrasound Doppler transducer (long arrow) placed over the temporal retinal vessels (short arrow) at the edge of the optic disc
Fig. 4
Fig. 4
The measurement sites were designated according to the distance from optic disc edge
Fig. 5
Fig. 5
Doppler angle θ estimation. The red solid line indicates the estimated flow direction and the red dashed line indicates the direction of ultrasound
Fig. 6
Fig. 6
The typical Doppler spectrogram of retinal vessel: the optic disc edge (a), and distal retinal vessel (b)
See this image and copyright information in PMC

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