Combining T(2) measurements and crusher gradients into a single ASL sequence for comparison of the measurement of water transport across the blood-brain barrier.
Combining T(2) measurements and crusher gradients into a single ASL sequence for comparison of the measurement of water transport across the blood-brain barrier.
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DOI：
10.1002/mrm.28613
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发表时间：
2021-05
影响因子：
3.3
通讯作者：
van Osch MJP
中科院分区：
文献类型：
--
作者：
Petitclerc L;Schmid S;Hirschler L;van Osch MJP
动脉自旋标记可以用来评估水分子通过血脑屏障的过渡时间，当与允许分离血管内信号和组织信号的序列模块结合时。双极梯度技术通过去除流动的自旋来测量血管内分数。T2自旋标记下松弛(TRUST)技术根据T2调节TE以区分血管内和血管外自旋。这些模块被组合成一个时间编码的伪连续动脉自旋标记序列，以比较它们的作用机制以及它们对血脑屏障中水转移的评估。该方案是在9名健康志愿者的扫描仪上获得的，他们提供了书面的知情同意。该序列由Hadamard编码的伪连续动脉自旋标记模块组成，紧随其后的是TRUST模块(有效的TES为0、40和80ms)和双极血流破碎梯度(2、4和∞cm/S)。另一项实验是用TRUST和3D梯度和自旋回波读出进行的。与TRUST方法相比，梯度不完全抵消了血管内信号，表现为标记后早期动脉中存在残留信号，以及对血管内分数的低估。信任模块允许我们通过T2的变化检测到比使用的破碎机梯度更深的水进入维管树的运输，因为它们的b值有限。在实施的技术中，TRUST允许我们在量化水通过血脑屏障的运输时间时，比使用(相对较弱的)破碎梯度的方法更深入血管树中跟随血管内信号。
Arterial spin labeling can be used to assess the transition time of water molecules across the blood–brain barrier when combined with sequence modules, which allow a separation of intravascular from tissue signal. The bipolar gradient technique measures the intravascular fraction by removing flowing spins. The T2‐relaxation‐under‐spin‐tagging (TRUST) technique modulates the TE to differentiate between intravascular and extravascular spins based on T2. These modules were combined into a single time‐encoded pseudo‐continuous arterial spin labeling sequence to compare their mechanisms of action as well as their assessment of water transition across the blood–brain barrier. This protocol was acquired on a scanner with 9 healthy volunteers who provided written, informed consent. The sequence consisted of a Hadamard‐encoded pseudo‐continuous arterial spin labeling module, followed by the TRUST module (effective TEs of 0, 40, and 80 ms) and bipolar flow‐crushing gradients (2, 4, and ∞ cm/s). An additional experiment was performed with TRUST and a 3D gradient and spin‐echo readout. Gradients imperfectly canceled the intravascular signal, as evidenced by the presence of residual signal in the arteries at early postlabeling delays as well as the underestimation of the intravascular fraction as compared with the TRUST method. The TRUST module allowed us to detect the transport of water deeper into the vascular tree through changes in T2 than the used crusher gradients could, with their limited b‐value. Of the implemented techniques, TRUST allowed us to follow intravascular signal deeper into the vascular tree than the approach with (relatively weak) crusher gradients when quantifying the transport time of water across the blood–brain barrier.
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