3T 下人类大脑的定量磁化率成像：一项多中心可重复性研究。
Quantitative susceptibility mapping of human brain at 3T: a multisite reproducibility study.
作者信息
Lin P-Y, Chao T-C, Wu M-L
机构信息
From the Department of Computer Science and Information Engineering (P.-Y.L., T.-C.C., M.-L.W.).
From the Department of Computer Science and Information Engineering (P.-Y.L., T.-C.C., M.-L.W.) Institute of Medical Informatics (T.-C.C., M.-L.W.), National Cheng Kung University, Tainan, Taiwan.
出版信息
AJNR Am J Neuroradiol. 2015 Mar;36(3):467-74. doi: 10.3174/ajnr.A4137. Epub 2014 Oct 22.
BACKGROUND AND PURPOSE
Quantitative susceptibility mapping of the human brain has demonstrated strong potential in examining iron deposition, which may help in investigating possible brain pathology. This study assesses the reproducibility of quantitative susceptibility mapping across different imaging sites.
MATERIALS AND METHODS
In this study, the susceptibility values of 5 regions of interest in the human brain were measured on 9 healthy subjects following calibration by using phantom experiments. Each of the subjects was imaged 5 times on 1 scanner with the same procedure repeated on 3 different 3T systems so that both within-site and cross-site quantitative susceptibility mapping precision levels could be assessed. Two quantitative susceptibility mapping algorithms, similar in principle, one by using iterative regularization (iterative quantitative susceptibility mapping) and the other with analytic optimal solutions (deterministic quantitative susceptibility mapping), were implemented, and their performances were compared.
RESULTS
Results show that while deterministic quantitative susceptibility mapping had nearly 700 times faster computation speed, residual streaking artifacts seem to be more prominent compared with iterative quantitative susceptibility mapping. With quantitative susceptibility mapping, the putamen, globus pallidus, and caudate nucleus showed smaller imprecision on the order of 0.005 ppm, whereas the red nucleus and substantia nigra, closer to the skull base, had a somewhat larger imprecision of approximately 0.01 ppm. Cross-site errors were not significantly larger than within-site errors. Possible sources of estimation errors are discussed.
CONCLUSIONS
The reproducibility of quantitative susceptibility mapping in the human brain in vivo is regionally dependent, and the precision levels achieved with quantitative susceptibility mapping should allow longitudinal and multisite studies such as aging-related changes in brain tissue magnetic susceptibility.
背景与目的
人脑的定量磁化率图谱在检测铁沉积方面已显示出强大潜力，这可能有助于研究潜在的脑部病变。本研究评估了不同成像部位定量磁化率图谱的可重复性。
材料与方法
在本研究中，通过体模实验校准后，对9名健康受试者大脑中5个感兴趣区域的磁化率值进行了测量。每个受试者在1台扫描仪上成像5次，并在3台不同的3T系统上重复相同程序，以便能够评估位点内和跨位点定量磁化率图谱的精确水平。实施了两种原理相似的定量磁化率图谱算法，一种使用迭代正则化（迭代定量磁化率图谱），另一种具有解析最优解（确定性定量磁化率图谱），并比较了它们的性能。
结果
结果表明，虽然确定性定量磁化率图谱的计算速度快近700倍，但与迭代定量磁化率图谱相比，残余条纹伪影似乎更明显。使用定量磁化率图谱时，壳核、苍白球和尾状核的不精确性较小，约为0.005 ppm量级，而更靠近颅底的红核和黑质的不精确性略大，约为0.01 ppm。跨位点误差并不显著大于位点内误差。讨论了估计误差的可能来源。
结论
人脑活体定量磁化率图谱的可重复性具有区域依赖性，定量磁化率图谱所达到的精确水平应能支持纵向和多部位研究，如脑组织磁化率与衰老相关的变化。
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