Analysis of deep microcirculation in cerebral cortex by Doppler optical coherence tomography

为了显示深埋在大脑皮质组织中的微血管，利用血流引起的多普勒频移作为检测OCT信号中血管的标志。由多普勒OCT技术获得的血流速度的三维分布显示了穿透性微血管以及深达1.5 mm的大脑皮质微血管。根据血流方向和血流的搏动性来区分穿透小动脉和小静脉。电刺激后掌可使初级躯体感觉皮层后爪区的穿透小动脉(约为对照的13%)和软脑膜小动脉(10%)的血流速度显著增加，而其他脑区的微血管血流速度无明显变化。微血管在深度方向的结构和血流信息可以帮助我们了解大脑皮层各层和功能柱之间的血流规律。

In order to visualize microvessels deeply embedded in the cortical tissue of brain, the Doppler frequency shift caused by blood flow is used as a marker to find out blood vessels in OCT signals. The 3-dimensional distribution of blood flow velocity obtained by Doppler OCT technique delineated penetrating microvessels as well as microvessels running deep in the cerebral cortex up to 1.5 mm depth. Penetrating arterioles were discriminated from venules based on the flow direction and pulsatility of blood flow. Electrical stimulus of hindpaw induced significant velocity increase in the penetrating arterioles (about 13% of the control value) and pial arterioles (10%) in the hindpaw area of primary somatosensory (S1) cortex, while the flow velocity did not change significantly in microvessels in the other area of S1 cortex. The information of structure and blood flow of microvessels in the direction of depth can help us to understand blood flow regulation among layers as well as functional columns of cerebral cortex.