Department of Imaging Physics, the University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA.
Magn Reson Med. 2018 Jun;79(6):3239-3248. doi: 10.1002/mrm.26992. Epub 2017 Nov 1.
To explore the effects of noise and error on kinetic analyses of tumor metabolism using hyperpolarized [1- C] pyruvate.
Numerical simulations were performed to systematically investigate the effects of noise, the number of unknowns, and error in kinetic parameter estimates on kinetic analysis of the apparent rate of chemical conversion from hyperpolarized pyruvate to lactate (k ). A pharmacokinetic model with two physical and two chemical pools of hyperpolarized spins was used to generate and analyze the synthetic data.
The reproducibility of k estimates worsened quickly when peak signal-to-noise ratio for hyperpolarized pyruvate was below approximately 20. The accuracy of k estimates was most sensitive to errors in high excitation angles, the vascular blood volume fraction (v ), and the rate of pyruvate extravasation (k ), and was least sensitive to errors in the T of pyruvate. When v and/or k were fit as additional unknowns, the accuracy of k estimates suffered, and when the vascular input function of pyruvate was also fit, the reproducibility of k estimates worsened.
The accuracy and precision of k estimates improve substantially for peak signal-to-noise ratio above approximately 20. Accurate estimates of perfusion parameters (combinations of v , k , and the pyruvate vascular input function) and transmit calibration at high excitation angles have the greatest effect on the accuracy of kinetic analyses. Magn Reson Med 79:3239-3248, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
使用极化 [1-13C] 丙酮酸探索噪声和误差对肿瘤代谢动力学分析的影响。
进行数值模拟，系统研究噪声、未知数数量和动力学参数估计误差对极化丙酮酸向乳酸转化的表观化学转换率（k）的动力学分析的影响。使用具有两个物理和两个化学极化自旋池的药代动力学模型生成和分析合成数据。
当极化丙酮酸的峰信噪比低于约 20 时，k 估计的可重复性迅速恶化。k 估计的准确性对高激发角、血管血容量分数（v）和丙酮酸外渗率（k）的误差最敏感，对丙酮酸 T 的误差最不敏感。当 v 和/或 k 拟合为额外未知数时，k 估计的准确性会受到影响，而当拟合丙酮酸的血管输入函数时，k 估计的可重复性会恶化。
当峰信噪比高于约 20 时，k 估计的准确性和精密度会大大提高。准确估计灌注参数（v、k 和丙酮酸血管输入函数的组合）和在高激发角下进行传输校准对动力学分析的准确性影响最大。磁共振医学 79:3239-3248,2018。©2017 年国际磁共振医学学会。
