Improved accuracy of human cerebral blood perfusion measurements using arterial spin labeling: Accounting for capillary water permeability
Improved accuracy of human cerebral blood perfusion measurements using arterial spin labeling: Accounting for capillary water permeability
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DOI：
10.1002/mrm.10180
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发表时间：
2002-07-01
影响因子：
3.3
通讯作者：
Tofts, PS
中科院分区：
文献类型：
--
作者：
Parkes, LM;Tofts, PS
提出了一种用于动脉自旋标记（ASL）灌注定量的双室交换模型，该模型修正了毛细管壁对水具有无限渗透性的假设。该模型结合了一个血管外腔室和一个血液腔室，毛细血管壁的渗透性表面积积（PS）表征了水在腔室之间的通过。新模型预测，标记自旋在交换前在血液室中停留的时间更长。这使得准确的血液T(1)测量对于灌注量化至关重要；相反，组织T(1)测量不太重要，对于脉冲ASL实验可能是不必要的。与单室模型相比，该模型在1.5T时对人体成像的灌注估计减少了62%。对于1.5T的典型人体灌注率，可以假设静脉流出信号可以忽略不计。这简化了解决方案，只比单室模型多引入一个参数，PS/v(bw)，其中v（bw）是单位体积组织的分数血水量。简化后的模型可以更好地拟合在不同延迟时间下收集的连续ASL数据。拟合得到合理的灌注和PS/v（bw）值。(C) 2002 Wiley-Liss, Inc。
A two-compartment exchange model for perfusion quantification using arterial spin labeling (ASL) is presented, which corrects for the assumption that the capillary wall has infinite permeability to water. The model incorporates an extravascular and a blood compartment with the permeability surface area product (PS) of the capillary wall characterizing the passage of water between the compartments. The new model predicts that labeled spins spend longer in the blood compartment before exchange. This makes an accurate blood T(1) measurement crucial for perfusion quantification; conversely, the tissue T(1) measurement is less important and may be unecessary for pulsed ASL experiments. The model gives up to 62% reduction in perfusion estimate for human imaging at 1.5T compared to the single compartment model. For typical human perfusion rates at 1.5T it can be assumed that the venous outflow signal is negligible. This simplifies the solution, introducing only one more parameter than the single compartment model, PS/v(bw), where v(bw) is the fractional blood water volume per unit volume of tissue. The simplified model produces an improved fit to continuous ASL data collected at varying delay time. The fitting yields reasonable values for perfusion and PS/v(bw). (C) 2002 Wiley-Liss, Inc.