Hohmann Tim, Kessler Jacqueline, Grabiec Urszula, Bache Matthias, Vordermark Dyrk, Dehghani Faramarz
Department of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle, (Saale), Germany.
Department of Radiotherapy, Martin Luther University Halle-Wittenberg, Halle, (Saale), Germany.
Histol Histopathol. 2018 May;33(5):475-485. doi: 10.14670/HH-11-945. Epub 2017 Nov 15.
Radiation therapy belongs to the most common approaches for cancer therapy leading amongst others to DNA damage like double strand breaks (DSB). DSB can be used as a marker for the effect of radiation on cells. For visualization and assessing the extent of DNA damage the γH2AX foci assay is frequently used. The analysis of the γH2AX foci assay remains complicated as the number of γH2AX foci has to be counted. The quantification is mostly done manually, being time consuming and leading to person-dependent variations. Therefore, we present a method to automatically analyze the number of foci inside nuclei, facilitating and quickening the analysis of DSBs with high reliability in fluorescent images. First nuclei were detected in fluorescent images. Afterwards, the nuclei were analyzed independently from each other with a local thresholding algorithm. This approach allowed accounting for different levels of noise and detection of the foci inside the respective nucleus, using Hough transformation searching for circles. The presented algorithm was able to correctly classify most foci in cases of "high" and "average" image quality (sensitivity>0.8) with a low rate of false positive detections (positive predictive value (PPV)>0.98). In cases of "low" image quality the approach had a decreased sensitivity (0.7-0.9), depending on the manual control counter. The PPV remained high (PPV>0.91). Compared to other automatic approaches the presented algorithm had a higher sensitivity and PPV. The used automatic foci detection algorithm was capable of detecting foci with high sensitivity and PPV. Thus it can be used for automatic analysis of images of varying quality.
放射治疗是癌症治疗中最常见的方法之一，它会导致包括双链断裂（DSB）在内的DNA损伤。DSB可作为辐射对细胞影响的标志物。为了可视化和评估DNA损伤程度，经常使用γH2AX焦点检测法。γH2AX焦点检测法的分析仍然很复杂，因为必须对γH2AX焦点的数量进行计数。定量大多是手动完成的，既耗时又会导致因人而异的差异。因此，我们提出了一种自动分析细胞核内焦点数量的方法，以便在荧光图像中以高可靠性促进和加快对DSB的分析。首先在荧光图像中检测细胞核。然后，使用局部阈值算法对细胞核进行独立分析。这种方法能够考虑到不同程度的噪声，并利用霍夫变换搜索圆来检测各个细胞核内的焦点。在“高”和“平均”图像质量的情况下，所提出的算法能够正确分类大多数焦点（灵敏度>0.8），假阳性检测率较低（阳性预测值（PPV）>0.98）。在“低”图像质量的情况下，该方法的灵敏度会降低（0.7 - 0.9），具体取决于手动控制计数器。PPV仍然很高（PPV>0.91）。与其他自动方法相比，所提出的算法具有更高的灵敏度和PPV。所使用的自动焦点检测算法能够以高灵敏度和PPV检测焦点。因此，它可用于对不同质量图像的自动分析。
