IEEE Trans Med Imaging. 2022 Apr;41(4):782-792. doi: 10.1109/TMI.2021.3123912. Epub 2022 Apr 1.
An increased pulse pressure, due to arteries stiffening with age and cardiovascular disease, may lead to downstream brain damage in microvessels and cognitive decline. Brain-wide imaging of the pulsatility propagation from main feeding arteries to capillaries in small animals could improve our understanding of the link between pulsatility and cognitive decline. However, it requires higher spatiotemporal resolution and penetration depth than currently available with existing brain imaging techniques. Herein, we show the feasibility of performing Dynamic Ultrasound Localization Microscopy (DULM), a novel imaging approach to capture hemodynamics with a subwavelength resolution. By producing cine-loops of flowing microbubbles in 2D in the whole rodent brain lasting several cardiac cycles, DULM performed pulsatility measurements in microvessels in-depth, in vivo, with and without craniotomy. Cortical veins and arteries were shown to have a significatively different pulsatility index and the method was compared against Contrast Enhanced Ultrafast Ultrasound Doppler (CEUFD) pulsatility measurements.
由于动脉随着年龄的增长和心血管疾病而变硬，脉压增加可能导致微血管下游的脑损伤和认知能力下降。对小动物主要供养动脉到毛细血管的脉动传播进行全脑成像，可以提高我们对脉动与认知能力下降之间关系的理解。然而，这需要比现有脑成像技术更高的时空分辨率和穿透深度。本文展示了进行动态超声定位显微镜（DULM）的可行性，这是一种新的成像方法，可以以亚波长分辨率捕获血液动力学。通过在整个啮齿动物大脑中以 2D 形式产生持续几个心动周期的流动微泡的电影循环，DULM 在有和没有开颅术的情况下，在体内、深入地测量了微血管的脉动。结果表明，皮质静脉和动脉的脉动指数有显著差异，该方法与对比增强超快超声多谱勒（CEUFD）的脉动测量进行了比较。
