UnIC@RISE, Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Porto, Portugal.
Faculty of Medicine, University of Porto, Porto, Portugal.
Ultrasound Med Biol. 2024 May;50(5):751-759. doi: 10.1016/j.ultrasmedbio.2024.02.003. Epub 2024 Feb 28.
Neurovascular coupling (NVC) represents the increase in regional blood flow associated with neural activity. The aim here was to describe a new approach to non-invasive measurement of NVC by spectral analysis of the cerebral blood flow velocity (CBFV) with transcranial Doppler.
In a sample of 20 healthy participants, we monitored systolic CBFV in the left posterior cerebral artery (PCA) during off (eyes closed) and on (flickering checkerboard) periods. The contralateral middle cerebral artery was simultaneously monitored as a control. Each participant was submitted to three experiments, each having five cycles, with increasing duration of the cycles, from 10 s (0.1 Hz) to 20 s (0.05 Hz) and lastly 40 s (0.025 Hz), half the time for on and for off periods, constituting a total of 6 min. The successive cycles were expected to cause oscillation in CBFV in a sinusoidal pattern that could be characterized by spectral analysis. We also measured the classic CBFV overshoot as the relative increase in percentage of systolic CBFV from baseline. The relationship and agreement between the two methods were analyzed by linear regression and Bland-Altman plots. In every participant, a clear peak of amplitude in the PCA CBFV spectrum was discernible at 0.1, 0.05 and 0.025 Hz of visual stimulation.
On average, this amplitude was 7.1 ± 2.3%, 10.9 ± 3.5% and 17.3 ± 6.5%, respectively. This response contrasted significantly with an absent peak in middle cerebral artery monitoring (p < 0.0001). The spectral amplitude and classic overshoot were highly correlated and linearly related (p < 0.0001).
NVC can be quantified by the spectral amplitude of PCA CBFV at slower and higher frequencies of visual stimulation. This method represents an alternative to classic overshoot without the need for stimulus marking or synchronization.
神经血管耦合（NVC）代表与神经活动相关的局部血流增加。本研究旨在描述一种新的经颅多普勒脑血流速度（CBFV）谱分析无创测量 NVC 的方法。
在 20 名健康参与者的样本中，我们在闭眼（关）和闪烁棋盘（开）期间监测左侧大脑后动脉（PCA）的收缩期 CBFV。同时监测对侧大脑中动脉作为对照。每位参与者进行三项实验，每个实验有五个周期，周期持续时间逐渐增加，从 10 秒（0.1 Hz）增加到 20 秒（0.05 Hz），最后增加到 40 秒（0.025 Hz），开和关的时间各半，共 6 分钟。预计连续的周期会导致 CBFV 呈正弦波样震荡，可以通过频谱分析来描述。我们还测量了经典的 CBFV 超射，即收缩期 CBFV 相对于基线的相对增加百分比。通过线性回归和 Bland-Altman 图分析两种方法之间的关系和一致性。在每个参与者中，在视觉刺激 0.1、0.05 和 0.025 Hz 时，可以清楚地看到 PCA CBFV 谱的幅度峰值。
平均而言，该幅度分别为 7.1 ± 2.3%、10.9 ± 3.5%和 17.3 ± 6.5%。与中动脉监测中不存在峰值形成鲜明对比（p < 0.0001）。频谱幅度与经典超射高度相关且呈线性相关（p < 0.0001）。
可以通过较慢和较高频率的视觉刺激的 PCA CBFV 频谱幅度来定量 NVC。这种方法代表了经典超射的替代方法，无需刺激标记或同步。
