Single-coil arterial spin-tagging for estimating cerebral blood flow as viewed from the capillary: Relative contributions of intra- and extravascular signal
Single-coil arterial spin-tagging for estimating cerebral blood flow as viewed from the capillary: Relative contributions of intra- and extravascular signal
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DOI：
10.1002/mrm.1215
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发表时间：
2001-09-01
影响因子：
3.3
通讯作者：
Fenstermacher, J
中科院分区：
文献类型：
--
作者：
Ewing, JR;Cao, Y;Fenstermacher, J
单毛细血管模型被应用于交换微血管的水在脑实质中，并用于计算血脑流量的水;稳态动脉自旋标记（AST）技术估计脑血流量（CBF）的理论进行了修订，将血管外（组织）和毛细血管信号的存在。单线圈AST实验的一个关键因素是磁化转移（MT）缩短了血管外水的有效T-1，使其成为毛细血管血液T-1的四分之一。此外，平均毛细血管通过时间是血管外水的T-1的数量级。单线圈AST实验与其他使用水作为CBF测量指标的方法不同，因为在正常生理条件下，血管内和血管外室中的反向质子（流量依赖性）数量几乎相等。考虑以下问题：单线圈AST对比度在静息CBF中是否呈线性？单线圈AST技术中的对比度在正常组织的CBF变化下可能是线性的吗？在中风和脑肿瘤等常见疾病中，对比度可能是线性的吗？我们证明，如果在微血管中的反转质子的人口被包括在实验中，反转质子的体素人口将在很宽的流量值范围内与流量近似线性。我们预测，单线圈AST实验将系统地高估静息CBF的流量在正常范围内，在正常组织中的CBF的变化将产生近似线性响应AST测量，最后，我们预测的操作特性的测量在常见的脑病变。(C)2001 Wiley-Liss，Inc.
The single-capillary model was applied to the exchange microvessels for water in the cerebral parenchyma and used to calculate blood-to-brain flux of water; the theory of the steady-state arterial spin-tagging (AST) technique for estimating cerebral blood flow (CBF) was revised to incorporate the presence of both extravascular (tissue) and capillary signal. A crucial element of the single-coil AST experiment is that magnetization transfer (MT) shortens the effective T-1 of the extravascular water, making it one-quarter that of the T-1 of capillary blood. Furthermore, the mean capillary transit time is on the order of the T-1 of the extravascular water. The single-coil AST experiment is distinguished from other methods which use water as an indicator for measurement of CBF in that the (flow-dependent) populations of inverted protons in the intra- and extravascular compartments can be nearly equal for normal physiological conditions. The following questions are considered: Is single-coil AST contrast linear in resting CBF? Is contrast in the single-coil AST technique likely to be linear under changes in CBF in normal tissue? Is the contrast likely to be linear in such common pathologies as stroke and cerebral tumor? We demonstrate that, if the population of inverted protons in the microvessels is included in the experiment, the voxel population of inverted protons will be approximately linear with flow across a broad range of flow values. We predict that the single-coil AST experiment will systematically overestimate resting CBF for flows in the normal range, that changes in CBF in normal tissue will produce an approximately linear response in AST measurement, and, finally, we predict the operating characteristics of the measurement in common cerebral pathologies. (C) 2001 Wiley-Liss, Inc.