Preclinical imaging, especially of rodent models, plays a major role in experimental ophthalmology. Our aim was to determine if ultrasound can be used to visualize and measure flow dynamics in the retrobulbar vessels supplying and draining the eye and the potential of contrast microbubbles to provide image and measurement enhancement. To accomplish this, we used a 128-element, 18 MHz linear array ultrasound probe and performed plane-wave imaging of the eyes of Sprague Dawley rats. Compound images were acquired by emitting unfocused wavefronts at multiple angles and combining echo data from all angles to form individual B-scans. Multiple imaging sequences were utilized, compounding up to six angles, with imaging rate of up to 3000 compound B-scans per second and sequence durations from 1.5 to 180 s. Data were acquired before and after intravenous introduction of contrast microbubbles. We found the total power of the Doppler signal in the image plane to increase approximately 20 fold after injection of contrast, followed by an exponential decay to baseline in about 90 s, The best-fit time constant of the decay averaged 41 s. While major vessels and the retinal/choroidal complex were evident pre-contrast, they were dramatically enhanced with contrast present, with details such as choroidal arterioles seen only with contrast. Ocular arteriovenous transit time determined from comparative enhancement curves in arteries and veins was approximately 0.2 s. In conclusion, plane wave ultrasound, especially with enhancement by contrast microbubbles, offers a means for the study of ocular hemodynamics using the rat eye as a model.

中文翻译：

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对比增强的大鼠眼平面波超声成像。

临床前成像，尤其是啮齿动物模型的临床前成像，在实验眼科中起着重要作用。我们的目标是确定超声是否可用于可视化和测量供球和引流眼球的后球血管中的血流动力学，以及对比微泡提供图像和测量增强的潜力。为此，我们使用了128元素，18 MHz线性阵列超声探头，并对Sprague Dawley大鼠的眼睛进行了平面波成像。通过以多个角度发射未聚焦的波前并组合来自所有角度的回波数据以形成单独的B扫描来获取复合图像。利用了多个成像序列，最多可合成六个角度，成像速率高达每秒3000次复合B扫描，序列持续时间为1.5到180 s。在静脉内注入造影剂微泡之前和之后获取数据。我们发现，注入对比剂后，图像平面中多普勒信号的总功率增加约20倍，然后在大约90 s内呈指数衰减至基线，衰减的最佳拟合时间常数平均为41 s。尽管主要血管和视网膜/脉络膜复合体在造影前很明显，但在存在造影剂的情况下它们显着增强，仅在造影剂的情况下可以看到脉络膜小动脉等细节。根据动脉和静脉中的比较增强曲线确定的眼动静脉传输时间约为0.2 s。总之，平面波超声，尤其是通过对比微泡增强的超声，提供了一种以大鼠眼为模型研究眼部血流动力学的手段。