A resolution criterion for electron tomography based on cross-validation
A resolution criterion for electron tomography based on cross-validation
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DOI：
10.1016/j.jsb.2005.04.006
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发表时间：
2005-08-01
影响因子：
3
通讯作者：
Steven, AC
中科院分区：
文献类型：
--
作者：
Cardone, G;Grünewald, K;Steven, AC
尽管在电子层析成像方面取得了很大进展，但分辨率的定量评估仍然是一个有问题的问题。在单颗粒分析中使用的标准，基于测量从半数据集计算的密度图之间的一致性，由于断层体积的唯一性，不能直接应用。在这里，我们提出了基于交叉验证方法的两个标准。一种称为FSCe/o，是基于从倾斜系列的偶数和奇数成员计算的断层图像之间的傅立叶壳相关性比较。另一种称为噪声补偿留一法（NLOO），是基于原始投影和从所有其他投影计算的断层图像的相应重投影之间的傅立叶环相关性比较，考虑到不同的噪声统计。绘制为倾斜角的函数，它们允许对一系列投影的分辨率和质量控制的角度依赖性进行评估。综合所有预测，结果给出了解决方案的全球数字。对模拟断层图像的测试建立了这些标准和FSCref之间的一致性，FSCref是在已知参考结构和包含该结构的断层图像的相应部分之间计算的相关系数。当残余噪声是主要的分辨率限制因素时，这两个标准-FSCe/o和NLOO-是相互一致的。当倾斜增量的大小成为一个重要因素时，NLOO提供了一个更可靠的标准，正如预期的那样，尽管它是计算密集型的。适用于整个断层图像或选定的结构，NLOO也已经过测试实验断层数据。爱思唯尔公司出版
Despite much progress in electron tomography, quantitative assessment of resolution has remained a problematic issue. The criteria that are used in single particle analysis, based on gauging the consistency between density maps calculated from half data sets, are not directly applicable because of the uniqueness of a tomographic volume. Here, we propose two criteria based on a cross-validation approach. One, called FSCe/o, is based on a Fourier shell correlation comparison between tomograms calculated from the even and odd members of a tilt series. The other, called noise-compensated leave-one-out (NLOO), is based on Fourier ring correlation comparisons between an original projection and the corresponding reprojection of the tomogram calculated from all the other projections, taking into account the differing noise statistics. Plotted as a function of tilt angle, they allow assessment of the angular dependence of resolution and quality control over the series of projections. Integrated over all projections, the results give a global figure for resolution. Tests on simulated tomograms established consistency between these criteria and the FSCref, a correlation coefficient calculated between a known reference structure and the corresponding portion of a tomogram containing that structure. The two criteria-FSCe/o and NLOO-are mutually consistent when residual noise is the major resolution-limiting factor. When the size of the tilt increment becomes a significant factor, NLOO provides a more reliable criterion, as expected, although it is computationally intensive. Applicable to entire tomograms or selected structures, NLOO has also been tested on experimental tomographic data. Published by Elsevier Inc.