Observer-independent nodule-detectability index for low-dose lung cancer screening CT: a pilot study.
Observer-independent nodule-detectability index for low-dose lung cancer screening CT: a pilot study.
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低剂量肺癌筛查 CT 的独立于观察者的结节可检测性指数：一项试点研究。
DOI：
10.1007/s12194-013-0225-2
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发表时间：
2013
影响因子：
1.6
通讯作者：
Matsumoto T.
中科院分区：
文献类型：
--
作者：
Ohkubo M;Wada S;Kanai S;Ishikawa K;Marasinghe JC;Matsumoto T.
为使低剂量CT在肺癌筛查中的广泛应用，根据客观的评价标准确定最佳的扫描条件和图像重建是非常重要的。我们在这项研究中的目的是提出一个不需要观察者测试的结核可探测性的量化指标。必须确定CT图像上可见的结节的表观大小和密度，以不依赖于观察者的统计方法为基础制定结节可探测性指数。因此，我们引入了一种基于系统空间分辨率的CT图像计算机仿真技术，以准确地评估CT图像的大小和密度。通过使用用于低剂量CT筛查的扫描/重建参数设置，获得不同大小且具有不同结节密度和背景密度之间的对比度(ΔCT)的目标结节(理想球体)的可探测性指数。将该指数与结核可探测性观察者测试的定性结果进行了比较。随着靶结节直径或ΔCT的增大，指标值增大，提示结节的可见度提高。根据该指数，ΔCT为70、100或150Hounsfield单位的结节的检测下限分别约为6、5和4 mm。根据四名观察员的评估，指标值与结核可探测性有很好的相关性。建议的指数对于量化结核的可探测性是有效的，并通过观察者测试证实了其有效性。该指标在无观察者试验的低剂量CT肺癌筛查中确定最佳扫描/重建参数具有潜在的应用价值。
For the wide dissemination of lung cancer screening by low-dose computed tomography (CT), it is important to determine the optimal conditions for scan and image reconstruction based on objective standards of evaluation. Our aim in this study was to propose a quantitative index of nodule detectability without an observer test. It was essential to determine the apparent size and density of nodules visible on CT images for developing the nodule-detectability index based on a statistical observer-independent method. Therefore, we introduced a computer simulation technique for CT images based on the spatial resolution of the system to evaluate the size and density accurately. By use of scan/reconstruction parameter settings as employed for low-dose CT screening, a detectability index was obtained for target nodules (ideal spheres) of various sizes and with varying contrast (ΔCT) between nodule density and background density. The index was compared with the qualitative results of observer tests of nodule detectability. As the target nodule diameter or ΔCT was increased, the index value increased, implying improved nodule visibility. According to the index, the detection limits for nodules with ΔCTs of 70, 100, or 150 Hounsfield units were approximately 6, 5, and 4 mm in diameter, respectively. Index values were well correlated with nodule detectability as assessed by four observers. The proposed index was effective for quantifying nodule detectability, and its validity was confirmed by an observer test. This index has potential use in the determination of optimal scan/reconstruction parameters for lung cancer screening by low-dose CT without observer test.