Identical, but not the same: intra-site and inter-site reproducibility of fractional anisotropy measures on two 3.0T scanners.
Identical, but not the same: intra-site and inter-site reproducibility of fractional anisotropy measures on two 3.0T scanners.
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DOI：
10.1016/j.neuroimage.2010.03.046
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发表时间：
2010-07-15
期刊：
影响因子：
5.7
通讯作者：
Koepp, Matthias J.
中科院分区：
文献类型：
--
作者：
Vollmar, Christian;O'Muircheartaigh, Jonathan;Barker, Gareth J.;Symms, Mark R.;Thompson, Pamela;Kumari, Veena;Duncan, John S.;Richardson, Mark P.;Koepp, Matthias J.
扩散张量成像（DTI）越来越多地用于评估白色物质的完整性，因此，解决DTI测量的重测信度至关重要。在这项研究中，我们评估了两个名义上相同的3 T扫描仪在不同的网站在9个健康对照使用的DTI协议代表的典型当前的“最佳实践”，包括心脏门控，多通道头部线圈，并行成像和优化的扩散梯度参数的网站间和网站内的再现性。我们计算的变异系数（CV）和组内相关系数（ICC）的分数各向异性（FA）的措施，为整个大脑，为三个区域的利益（ROI），并为三个道来自这些ROI的概率跟踪。我们评估了仿射，非线性和基于模板的方法空间对齐FA地图的再现性的影响。FA的中心内CV范围为0.8%-3.0%，ICC范围为0.90 - 0.99，而中心间CV范围为1.0%-4.1%，ICC范围为0.82 - 0.99。与仿射配准相比，非线性图像配准提高了再现性。归一化到模板空间减少了受试者之间的变化，导致ICC值降低，并表明灵敏度可能降低。概率纤维束成像的CV比相应的种子ROI高约50%。整个扫描体积的再现图显示在主要白色物质束中小于5%的低变化，但在灰质区域中10-15%的较高变化。两台扫描仪中的一台显示出更好的部位内重现性，而两台扫描仪的部位内CV显著优于部位间CV。然而，当使用FA图的非线性配准时，平均中心间CV低于2%。研究中心间偏倚一致，研究中心2的FA值比研究中心1低1.0-1.5%。通过全局比例因子校正该偏倚，将中心间CV降低至中心内CV范围。我们的结果对于在更大人群中进行多中心DTI研究是令人鼓舞的，但也说明了图像处理管道对再现性的重要性。
Diffusion Tensor Imaging (DTI) is being increasingly used to assess white matter integrity and it is therefore paramount to address the test–retest reliability of DTI measures. In this study we assessed inter- and intra-site reproducibility of two nominally identical 3 T scanners at different sites in nine healthy controls using a DTI protocol representative of typical current “best practice” including cardiac gating, a multichannel head coil, parallel imaging and optimized diffusion gradient parameters. We calculated coefficients of variation (CV) and intraclass correlation coefficients (ICC) of fractional anisotropy (FA) measures for the whole brain, for three regions of interest (ROI) and for three tracts derived from these ROI by probabilistic tracking. We assessed the impact of affine, nonlinear and template based methods for spatially aligning FA maps on the reproducibility. The intra-site CV for FA ranged from 0.8% to 3.0% with ICC from 0.90 to 0.99, while the inter-site CV ranged from 1.0% to 4.1% with ICC of 0.82 to 0.99. Nonlinear image coregistration improved reproducibility compared to affine coregistration. Normalization to template space reduced the between-subject variation, resulting in lower ICC values and indicating a possibly reduced sensitivity. CV from probabilistic tractography were about 50% higher than for the corresponding seed ROI. Reproducibility maps of the whole scan volume showed a low variation of less than 5% in the major white matter tracts but higher variations of 10–15% in gray matter regions. One of the two scanners showed better intra-site reproducibility, while the intra-site CV for both scanners was significantly better than inter-site CV. However, when using nonlinear coregistration of FA maps, the average inter-site CV was below 2%. There was a consistent inter-site bias, FA values on site 2 were 1.0–1.5% lower than on site 1. Correction for this bias with a global scaling factor reduced the inter-site CV to the range of intra-site CV. Our results are encouraging for multi-centre DTI studies in larger populations, but also illustrate the importance of the image processing pipeline for reproducibility.
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影响因子：
5.7
作者：
Wheeler-Kingshott, CAM;Hickman, SJ;Barker, GJ
通讯作者：
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影响因子：
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作者：
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