Turner Robert
Wellcome Department of Imaging Neuroscience, Institute of Neurology, 12 Queen Square, London, WC1N 3BG, United Kingdom.
Neuroimage. 2002 Aug;16(4):1062-7. doi: 10.1006/nimg.2002.1082.
The draining vein problem is recognized as one of the most severe constraints on the spatial resolution of BOLD contrast fMRI, used widely in imaging neuroscience. Changes in blood oxygenation arising from local brain activity-related changes in blood flow propagate downstream in veins and can give rise to spurious activation at sites remote from neuronal activity. The geometry of the venous vasculature is quite regular in structure and is well depicted in photomicrographs. Quantitative analysis of this geometry, together with hydrodynamic considerations, permit upper bounds dependent on the area of cortical neuronal activity to be derived for the spatial extent of draining vein contamination. It is estimated that an activated cortical area of 100 mm(2) will generate an oxygenation change in venous blood that extends without dilution along the vein no more than 4.2 mm beyond the edge of the activated area. At greater distances along the draining vein this oxygenation change will be diluted. The model leads to a quantitative prediction of the functional form of this dilution.
引流静脉问题被认为是对广泛应用于成像神经科学的血氧水平依赖性功能磁共振成像（BOLD-fMRI）空间分辨率最严重的限制之一。局部脑活动相关的血流变化引起的血液氧合变化在静脉中向下游传播，并可能在远离神经元活动的部位产生假激活。静脉血管系统的几何结构在结构上相当规则，并且在显微照片中得到了很好的描绘。对这种几何结构进行定量分析，并结合流体动力学考虑，可以得出取决于皮质神经元活动区域的上限，用于确定引流静脉污染的空间范围。据估计，100平方毫米的激活皮质区域将在静脉血中产生氧合变化，该变化在不被稀释的情况下沿着静脉延伸，超出激活区域边缘不超过4.2毫米。在沿着引流静脉更远的距离处，这种氧合变化将被稀释。该模型对这种稀释的函数形式进行了定量预测。
