An analysis of the uncertainty and bias in DCE-MRI measurements using the spoiled gradient-recalled echo pulse sequence
An analysis of the uncertainty and bias in DCE-MRI measurements using the spoiled gradient-recalled echo pulse sequence
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DOI：
10.1118/1.4865790
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发表时间：
2014-03-01
期刊：
影响因子：
3.8
通讯作者：
Johnson, G. Allan
中科院分区：
文献类型：
--
作者：
Subashi, Ergys;Choudhury, Kingshuk R.;Johnson, G. Allan
目的：来自动态对比增强（DCE）MRI的药代动力学参数已用于100多项I期试验和研究者主导的研究。这些量的绝对值的比较需要估计它们各自的概率分布函数（PDF）。的DCE-MRI测量的统计变化进行了分析，通过考虑的基本来源的错误，在MR信号强度与扰相梯度回波（SPGR）pulse sequence.Methods：SPGR信号强度的方差产生的正交检测和激励翻转角的不一致。在[0-1] mM范围内（以0.1 mM为步长）的造影剂浓度的11个模型中以及在荷瘤小鼠的一次体内采集中测量噪声功率。使用自旋回波双角法在均匀的10 mM CuSO 4体模中确定翻转角的分布。通过SPGR方程的数值模拟，估计了用变翻转角（VFA）技术测量的宽范围T1值的PDF。在造影剂浓度的不确定性被纳入最常见的示踪剂交换动力学模型和PDF的推导出的药代动力学参数numbered.Results研究：VFA方法是一种无偏的技术，用于测量T1只有在激励翻转角的偏差的情况下。在体内测量的造影剂的时间依赖性浓度在理论预测的不确定性范围内。用SPGR脉冲序列测量K-trans的不确定度与测量注入前纵向弛豫时间（T1（0））的不确定度具有相同的量级，但总是高于测量注入前纵向弛豫时间（T1（0））的不确定度。估计该参数时可达到的最低偏倚/不确定度比测量进样前T1图时的偏倚/不确定度高约20%-70%。从扩展的Tofts模型推导出的分数体积参数被发现是非常敏感的信号强度的变化。注射前的T1地图的SNR表示的限制精度与Ktranss可以calculated.Conclusions：目前的小动物成像系统和脉冲序列强大的运动伪影有能力与DCE-MRI可重复的定量收购。在这些情况下，可以实现仅受生理变异性限制的精确度水平。c 2014年美国医学物理学家协会。
Purpose: The pharmacokinetic parameters derived from dynamic contrast-enhanced (DCE) MRI have been used in more than 100 phase I trials and investigator led studies. A comparison of the absolute values of these quantities requires an estimation of their respective probability distribution function (PDF). The statistical variation of the DCE-MRI measurement is analyzed by considering the fundamental sources of error in the MR signal intensity acquired with the spoiled gradient-echo (SPGR) pulse sequence.Methods: The variance in the SPGR signal intensity arises from quadrature detection and excitation flip angle inconsistency. The noise power was measured in 11 phantoms of contrast agent concentration in the range [0-1] mM (in steps of 0.1 mM) and in one in vivo acquisition of a tumor-bearing mouse. The distribution of the flip angle was determined in a uniform 10 mM CuSO4 phantom using the spin echo double angle method. The PDF of a wide range of T1 values measured with the varying flip angle (VFA) technique was estimated through numerical simulations of the SPGR equation. The resultant uncertainty in contrast agent concentration was incorporated in the most common model of tracer exchange kinetics and the PDF of the derived pharmacokinetic parameters was studied numerically.Results: The VFA method is an unbiased technique for measuring T1 only in the absence of bias in excitation flip angle. The time-dependent concentration of the contrast agent measured in vivo is within the theoretically predicted uncertainty. The uncertainty in measuring K-trans with SPGR pulse sequences is of the same order, but always higher than, the uncertainty in measuring the pre-injection longitudinal relaxation time (T1(0)). The lowest achievable bias/uncertainty in estimating this parameter is approximately 20%-70% higher than the bias/uncertainty in the measurement of the pre-injection T1 map. The fractional volume parameters derived from the extended Tofts model were found to be extremely sensitive to the variance in signal intensity. The SNR of the pre-injection T1 map indicates the limiting precision with which Ktrans can be calculated.Conclusions: Current small-animal imaging systems and pulse sequences robust to motion artifacts have the capacity for reproducible quantitative acquisitions with DCE-MRI. In these circumstances, it is feasible to achieve a level of precision limited only by physiologic variability. c 2014 American Association of Physicists in Medicine.