Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA.
Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, WA, USA; School of Electrical and Electronics Engineering, College of ICT Engineering, Chung-Ang University, Seoul, Korea.
Neurobiol Aging. 2018 Oct;70:148-159. doi: 10.1016/j.neurobiolaging.2018.06.017. Epub 2018 Jun 22.
Normal aging is associated with significant alterations in brain's vascular structure and function, which can lead to compromised cerebral circulation and increased risk of neurodegeneration. The in vivo examination of cerebral blood flow (CBF), including capillary beds, in aging brains with sufficient spatial detail remains challenging with current imaging modalities. In the present study, we use 3-dimensional (3-D) quantitative optical coherence tomography angiography (OCTA) to examine characteristic differences of the cerebral vasculatures and hemodynamics at the somatosensory cortex between old (16 months old) and young mice (2 months old) in vivo. The quantitative metrics include cortical vascular morphology, CBF, and capillary flow velocity. We show that compared with young mice, the pial arterial tortuosity increases by 14%, the capillary vessel density decreases by 15%, and the CBF reduces by 33% in the old mice. Most importantly, changes in capillary velocity and heterogeneity with aging are quantified for the first time with sufficiently high statistical power between young and old populations, with a 21% (p < 0.05) increase in capillary mean velocity and 19% (p ≤ 0.05) increase in velocity heterogeneity in the latter. Our findings through noninvasive imaging are in line with previous studies of vascular structure modification with aging, with additional quantitative assessment in capillary velocity enabled by advanced OCTA algorithms on a single imaging platform. The results offer OCTA as a promising neuroimaging tool to study vascular aging, which may shed new light on the investigations of vascular factors contributing to the pathophysiology of age-related neurodegenerative disorders.
正常衰老与大脑血管结构和功能的显著改变有关，这可能导致脑循环受损和神经退行性病变风险增加。目前的成像方式仍然难以在衰老大脑中以足够的空间细节对包括毛细血管床在内的脑血流 (CBF) 进行体内检查。在本研究中，我们使用三维 (3-D) 定量光相干断层扫描血管造影术 (OCTA) 来检查体内老年 (16 个月大) 和年轻 (2 个月大) 小鼠体感皮层的脑血管结构和血液动力学的特征差异。定量指标包括皮质血管形态、CBF 和毛细血管血流速度。我们发现，与年轻小鼠相比，老年小鼠的软脑膜动脉迂曲度增加了 14%，毛细血管密度降低了 15%，CBF 降低了 33%。最重要的是，首次在年轻和老年群体之间以足够高的统计效力定量评估了毛细血管速度的变化和异质性，后者的毛细血管平均速度增加了 21%（p < 0.05），速度异质性增加了 19%（p ≤ 0.05）。我们通过非侵入性成像发现的结果与血管结构随年龄变化的先前研究一致，并通过单成像平台上的先进 OCTA 算法在毛细血管速度方面进行了额外的定量评估。这些结果为 OCTA 作为一种有前途的神经影像学工具来研究血管老化提供了依据，这可能为研究血管因素对与年龄相关的神经退行性疾病的病理生理学的研究提供新的思路。
