Simultaneous T-2* and diffusion measurements with He-3
Simultaneous T-2* and diffusion measurements with He-3
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DOI：
10.1002/mrm.1910380607
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发表时间：
1997-12-01
影响因子：
3.3
通讯作者：
Bock, M
中科院分区：
文献类型：
--
作者：
Bock, M
最近有研究表明，利用超极化气体（如He-3）对人体肺部和气道进行磁共振成像是可能的。由于表观横向弛豫（T-2*衰减）和扩散对He-3成像的影响尚未量化，因此开发了一种同时测量这两个参数的成像脉冲序列，该成像脉冲序列产生两组具有不同回波间隔和扩散敏化梯度的多重回忆梯度回波图像。根据两个系列的指数信号衰减的差异，超极化和非极化3He样品的T-2*和扩散系数D可以在标准临床成像仪上使用自制的亥姆霍兹线圈进行测量。在纯3He超极化样品中，D值为（1.8 +/- 0.2）。测得10(-4)m(2)/s, T-2* = 36 +/- 13 ms, D =(0.3 +/- 0.1)。在玻尔兹曼极化He-3/O-2混合物中发现了10(-4)m(2)/s和T-2* = 136 +/- 66 ms。
It has recently been demonstrated that magnetic resonance (MR) imaging of human lungs and airways is possible with hyperpolarized gases such as He-3. Because the influence of the apparent transversal relaxation (T-2* decay) and diffusion in He-3 imaging have not been quantified, an imaging pulse sequence was developed to measure these two parameters simultaneously, The imaging pulse sequence generates two series of multiply recalled gradient echo images with both different echo-spacings and diffusion-sensitizing gradients. From differences in exponential signal decay between the two series, T-2* and diffusion coefficients, D, of both hyperpolarized and unpolarized 3He samples could be measured on a standard clinical imager using a home-built Helmholtz coil. In a hyperpolarized sample of pure 3He values of D (1.8 +/- 0.2) . 10(-4) m(2)/s and T-2* = 36 +/- 13 ms were measured, while D = (0.3 +/- 0.1) . 10(-4) m(2)/s and T-2* = 136 +/- 66 ms were found in a Boltzmann-polarized He-3/O-2 mixture.