Gómez Damián Pedro A, Sperl Jonathan I, Janich Martin A, Khegai Oleksandr, Wiesinger Florian, Glaser Steffen J, Haase Axel, Schwaiger Markus, Schulte Rolf F, Menzel Marion I
GE Global Research, 85748 Garching bei München, Germany ; Medical Engineering, Tecnológico de Monterrey, 64849 Monterrey, NL, Mexico ; Medical Engineering, Technische Universität München, 85748 Garching bei München, Germany.
GE Global Research, 85748 Garching bei München, Germany.
Radiol Res Pract. 2014;2014:871619. doi: 10.1155/2014/871619. Epub 2014 Dec 8.
Hyperpolarized (13)C imaging allows real-time in vivo measurements of metabolite levels. Quantification of metabolite conversion between [1-(13)C]pyruvate and downstream metabolites [1-(13)C]alanine, [1-(13)C]lactate, and [(13)C]bicarbonate can be achieved through kinetic modeling. Since pyruvate interacts dynamically and simultaneously with its downstream metabolites, the purpose of this work is the determination of parameter values through a multisite, dynamic model involving possible biochemical pathways present in MR spectroscopy. Kinetic modeling parameters were determined by fitting the multisite model to time-domain dynamic metabolite data. The results for different pyruvate doses were compared with those of different two-site models to evaluate the hypothesis that for identical data the uncertainty of a model and the signal-to-noise ratio determine the sensitivity in detecting small physiological differences in the target metabolism. In comparison to the two-site exchange models, the multisite model yielded metabolic conversion rates with smaller bias and smaller standard deviation, as demonstrated in simulations with different signal-to-noise ratio. Pyruvate dose effects observed previously were confirmed and quantified through metabolic conversion rate values. Parameter interdependency allowed an accurate quantification and can therefore be useful for monitoring metabolic activity in different tissues.
超极化（13）C成像可实现体内代谢物水平的实时测量。通过动力学建模可以对[1-（13）C]丙酮酸与下游代谢物[1-（13）C]丙氨酸、[1-（13）C]乳酸和[（13）C]碳酸氢盐之间的代谢物转化进行定量。由于丙酮酸与其下游代谢物动态且同时相互作用，本研究的目的是通过一个涉及磁共振波谱中可能存在的生化途径的多部位动态模型来确定参数值。通过将多部位模型拟合到时域动态代谢物数据来确定动力学建模参数。将不同丙酮酸剂量的结果与不同双部位模型的结果进行比较，以评估以下假设：对于相同的数据，模型的不确定性和信噪比决定了检测目标代谢中微小生理差异的灵敏度。与双部位交换模型相比，多部位模型产生的代谢转化率偏差更小、标准差更小，不同信噪比的模拟结果证明了这一点。先前观察到的丙酮酸剂量效应通过代谢转化率值得到了证实和量化。参数的相互依赖性允许进行准确的定量，因此可用于监测不同组织中的代谢活性。
