Optimal echo spacing for multi-echo imaging measurements of Bi-exponential T2 relaxation
Optimal echo spacing for multi-echo imaging measurements of Bi-exponential T2 relaxation
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DOI：
10.1016/j.jmr.2008.11.002
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发表时间：
2009-02-01
影响因子：
2.2
通讯作者：
Does, Mark D.
中科院分区：
文献类型：
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作者：
Dula, Adrienne N.;Gochberg, Daniel F.;Does, Mark D.
通过计算、解析解和模拟，研究了多回波成像脉冲序列双指数横向弛豫特性中回波间距和接收机带宽的权衡。在较大范围的分量T-2值和回波间距下，计算了双池模型四个参数标准差的Cramer-Rao下界。结果表明，在其他脉冲序列约束条件下，最佳回波间隔（TEopt）通常不是最小可用值。TEopt随短T-2时间常数的增大而增大，随长、短时间常数比值的减小而减小。给出了一个简单的TEopt模型，它是两个T-2时间常数和四个经验推导的标量的函数。(C) 2008爱思唯尔公司版权所有。
Calculations, analytical solutions, and simulations were used to investigate the trade-off of echo spacing and receiver bandwidth for the characterization of bi-exponential transverse relaxation using a multi-echo imaging pulse sequence. The Cramer-Rao lower bound of the standard deviation of the four parameters of a two-pool model was computed for a wide range of component T-2 values and echo spacing. The results demonstrate that optimal echo spacing (TEopt) is not generally the minimal available given other pulse sequence constraints. The TEopt increases with increasing value of the short T-2 time constant and decreases as the ratio of the long and short time constant decreases. A simple model of TEopt as a function of the two T-2 time constants and four empirically derived scalars is presented. (C) 2008 Elsevier Inc. All rights reserved.