Analysis of mcDESPOT- and CPMG-Derived Parameter Estimates for Two-Component Nonexchanging Systems
Analysis of mcDESPOT- and CPMG-Derived Parameter Estimates for Two-Component Nonexchanging Systems
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DOI：
10.1002/mrm.25801
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发表时间：
2016-06-01
影响因子：
3.3
通讯作者：
Spencer, Richard G.
中科院分区：
文献类型：
--
作者：
Bouhrara, Mustapha;Reiter, David A.;Spencer, Richard G.
目的：为了比较的可靠性和稳定性的多组件驱动的平衡单脉冲观测的T-1和T-2（mcDESPOT）和Carl-Purcell-Meiboom-Gill（CPMG）的方法参数estimation.Methods：的稳定性和可靠性的mcDESPOT和CPMG导出的参数估计进行了比较，通过检查的能量表面，评估模型的sloppiness，和蒙特卡洛模拟。在等时间基础上进行比较，并假设为双组分系统。参数估计偏差，反射精度，和分散体，反射精度，推导出一系列的信号噪声比（SNR）和松弛parameters.Results：纳入mcDESPOT信号模型的参数的能量表面表现出平坦度，一个复杂的结构的局部极小值，和噪声的不稳定性，在更大程度上比相应的表面CPMG。虽然mcDESPOT和CPMG表现良好，在高SNR，CPMG的方法产生了相当大的准确性和精度在较低的SNR.Conclusion参数估计：mcDESPOT和CPMG都允许高质量的参数估计SNR下，在临床上可以实现在许多情况下，取决于可用的硬件和分辨率和采集时间的限制。在中高SNR下，结合两步相位增量的mcDESPOT方法可以产生准确的参数估计，同时提供通过CPMG无法获得的纵向弛豫时间值。然而，在低SNR下，CPMG方法更稳定，并且提供上级参数估计。(C)2015 Wiley Periodicals，Inc.
Purpose: To compare the reliability and stability of the multicomponent-driven equilibrium single pulse observation of T-1 and T-2 (mcDESPOT) and Carl-Purcell-Meiboom-Gill (CPMG) approaches to parameter estimation.Methods: The stability and reliability of mcDESPOT and CPMG-derived parameter estimates were compared through examination of energy surfaces, evaluation of model sloppiness, and Monte Carlo simulations. Comparisons were performed on an equal time basis and assuming a two-component system. Parameter estimation bias, reflecting accuracy, and dispersion, reflecting precision, were derived for a range of signal-to-noise ratios (SNRs) and relaxation parameters.Results: The energy surfaces for parameters incorporated into the mcDESPOT signal model exhibit flatness, a complex structure of local minima, and instability to noise to a much greater extent than the corresponding surfaces for CPMG. Although both mcDESPOT and CPMG performed well at high SNR, the CPMG approach yielded parameter estimates of considerably greater accuracy and precision at lower SNR.Conclusion: mcDESPOT and CPMG both permit high-quality parameter estimates under SNR that are clinically achievable under many circumstances, depending upon available hardware and resolution and acquisition time constraints. At moderate to high SNR, the mcDESPOT approach incorporating two-step phase increments can yield accurate parameter estimates while providing values for longitudinal relaxation times that are not available through CPMG. However, at low SNR, the CPMG approach is more stable and provides superior parameter estimates. (C) 2015 Wiley Periodicals, Inc.