The Lung Image Database Consortium (LIDC): A comparison of different size metrics for pulmonary nodule measurements
The Lung Image Database Consortium (LIDC): A comparison of different size metrics for pulmonary nodule measurements
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DOI：
10.1016/j.acra.2007.09.005
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发表时间：
2007-12-01
影响因子：
4.8
通讯作者：
Clarke, Laurence P.
中科院分区：
文献类型：
--
作者：
Reeves, Anthony P.;Biancardi, Alberto M.;Clarke, Laurence P.
理论基础和目标。目的是调查在估计肺结节大小时选择不同的指标作为结节特征和计算机辅助检测系统性能的影响，因为计算机辅助检测系统相对于给定的结节大小范围总是合格的。这项研究使用了肺图像数据库联盟(LIDC)记录的265例全肺CT扫描，使用他们的方案进行结节评估。每一次检查的病变都由四名经验丰富的放射科医生独立审查，他们为大于3毫米的结节提供边界标记。考虑了基于边界标记的四个尺寸度量：单个图像切片上的一维和两个二维测量以及基于所有图像切片的体积测量。对放射科医生的边界进行处理，并对有四个标记的边界进行分析，以表征放射科医生间的差异，而至少有一个标记的边界被用来检查两个度量之间的差异。对注释的处理发现了127个由所有四名放射科医生标记的结节，以及一组扩展的518个结节，每个结节至少有一次观察，三维大小从2.03毫米到29.4毫米(平均7.05毫米，中位数5.71毫米)。观察到所有这些指标都有很高的观察者间差异：三维、一维和二维尺寸指标的95%的估计标准偏差分别在以下范围内(以毫米为单位)：0.49-1.25、0.67-2.55、0.78-2.11和0.96-2.69。两种度量指标之间也有很大的差异：一维体积估测的概率覆盖区域宽度为0.95，两个10 mm的二维尺寸测量结果分别为7.32、7.72和6.29 mm。用于性能评估的数据子集的选择受大小度量选择的影响很大。LIDC计划在其数据库中包括每个结核的单一大小测量。这一指标的目的不是作为结核大小的黄金标准；相反，它的目的是促进选择独特的可重复大小有限的结节子集。
Rationale and Objectives. The goal was to investigate the effects of choosing between different metrics in estimating the size of pulmonary nodules as a factor both of nodule characterization and of performance of computer aided detection systems, because the latter are always qualified with respect to a given size range of nodules.Materials and Methods. This study used 265 whole-lung CT scans documented by the Lung Image Database Consortium (LIDC) using their protocol for nodule evaluation. Each inspected lesion was reviewed independently by four experienced radiologists who provided boundary markings for nodules larger than 3 mm. Four size metrics, based on the boundary markings, were considered: a unidimensional and two bidimensional measures on a single image slice and a volumetric measurement based on all the image slices. The radiologist boundaries were processed and those with four markings were analyzed to characterize the interradiologist variation, while those with at least one marking were used to examine the difference between the metrics.Results. The processing of the annotations found 127 nodules marked by all of the four radiologists and an extended set of 518 nodules each having at least one observation with three-dimensional sizes ranging from 2.03 to 29.4 mm (average 7.05 mm, median 5.71 mm). A very high interobserver variation was observed for all these metrics: 95% of estimated standard deviations were in the following ranges for the three-dimensional, unidimensional, and two bidimensional size metrics, respectively (in mm): 0.49-1.25, 0.67-2.55, 0.78-2.11, and 0.96-2.69. Also, a very large difference among the metrics was observed: 0.95 probability-coverage region widths for the volume estimation conditional on unidimensional, and the two bidimensional size measurements of 10 mm were 7.32, 7.72, and 6.29 mm, respectively.Conclusions. The selection of data subsets for performance evaluation is highly impacted by the size metric choice. The LIDC plans to include a single size measure for each nodule in its database. This metric is not intended as a gold standard for nodule size; rather, it is intended to facilitate the selection of unique repeatable size limited nodule subsets.