Abstract：
Currently, brain iron content represents a new neuromarker for understanding the physiopathological mechanisms leading to Parkinson\'s disease (PD). In vivo quantification of biological iron is possible by reconstructing magnetic susceptibility maps obtained using quantitative susceptibility mapping (QSM). Applying QSM is challenging, as up to now, no standardization of acquisition protocols and phase image processing has emerged from referenced studies. Our objectives were to compare the accuracy and the sensitivity of 10 QSM pipelines built from algorithms from the literature, applied on phantoms data and on brain data. Two phantoms, with known magnetic susceptibility ranges, were created from several solutions of gadolinium chelate. Twenty healthy volunteers from two age groups were included. Phantoms and brain data were acquired at 1.5 and 3 T, respectively. Susceptibility-weighted images were obtained using a 3D multigradient-recalled-echo sequence. For brain data, 3D anatomical T1- and T2-weighted images were also acquired to segment the deep gray nuclei of interest. Concerning in vitro data, the linear dependence of magnetic susceptibility versus gadolinium concentration and deviations from the theoretically expected values were calculated. For brain data, the accuracy and sensitivity of the QSM pipelines were evaluated in comparison with results from the literature and regarding the expected magnetic susceptibility increase with age, respectively. A nonparametric Mann-Whitney U-test was used to compare the magnetic susceptibility quantification in deep gray nuclei between the two age groups. Our methodology enabled quantifying magnetic susceptibility in human brain and the results were consistent with those from the literature. Statistically significant differences were obtained between the two age groups in all cerebral regions of interest. Our results show the importance of optimizing QSM pipelines according to the application and the targeted magnetic susceptibility range, to achieve accurate quantification. We were able to define the optimal QSM pipeline for future applications on patients with PD.
摘要：
目前,脑铁含量为了解导致帕金森病（PD）的病理生理学机制提供了新的神经标记。通过重建使用定量磁化率映射（QSM）获得的磁化率图，可以对生物铁进行体内定量。应用QSM具有挑战性，到现在为止,从引用的研究中没有出现采集协议和相位图像处理的标准化。我们的目标是比较从文献中的算法构建的10个QSM管道的准确性和灵敏度，应用于幻影数据和大脑数据。两个幻影，具有已知的磁化率范围，由钆螯合物的几种溶液产生。包括来自两个年龄组的20名健康志愿者。在1.5和3T时获取幻影和大脑数据，分别。使用3D多梯度召回回波序列获得磁化率加权图像。对于大脑数据，还获取了3D解剖T1和T2加权图像以分割感兴趣的深灰色核。关于体外数据，计算了磁化率对钆浓度的线性依赖性以及与理论期望值的偏差。对于大脑数据，将QSM管道的准确性和灵敏度与文献中的结果进行了比较，并评估了预期的磁化率随年龄的增加，分别。使用非参数Mann-WhitneyU检验比较了两个年龄组之间深灰色核的磁化率定量。我们的方法能够量化人脑的磁化率，结果与文献一致。在所有感兴趣的大脑区域中，两个年龄组之间获得了统计学上的显着差异。我们的结果表明，根据应用和目标磁化率范围优化QSM管道的重要性，实现准确量化。我们能够为PD患者的未来应用定义最佳的QSM管道。
