Development of 4-dimentional image construction for sequential chest radiograph.

为了帮助放射科医生在诊断筛选胸片，时间减影技术，使用数字图像处理的发展。两个连续图像的精确图像配准使我们能够检测到它们之间的“差异图像”中的细微变化。本研究介绍了一种基于匹配“肺部纹理”的新方法，从计算机X线摄影系统拍摄的病例中选择了29对有和无时间变化的连续后前位胸片。图像配准与“肺纹理”在以前和当前的X线照片的局部匹配。由8名放射科医生进行了观察者表现测试，其中有和没有指示它们之间的“差异图像”。观察者与时间减影图像的表现显示，8名观察者中有6名诊断具有较高的灵敏度（平均值，43.9%至55.3%）和相当的假阳性反应。AFROC（Alternative Free-Response Receiver Operating Characteristics）曲线下平均面积也从0.596提高到0.647，显示出统计学显著性。

To aid radiologists in the diagnosis of screening chest radiographs, a temporal subtraction technique using digital image processing was developed. The accurate image registration of two sequential images enables us to detect even subtle changes in the "difference image" between them. In this study, a new method based on matching "lung markings" is introduced.Twenty-nine pairs of sequential posteroanterior chest radiographs with and without the temporal changes were selected from cases taken with the computed radiography system. Image registration was employed with the local matching of "lung markings" in previous and current radiographs. Observer performance tests with and without indicating the "difference image" between them was carried out by eight radiologists.Observer performance with the temporal subtraction image shows that six of eight observers diagnosed with higher sensitivity (mean, 43.9% to 55.3%) and comparable false positive response. Mean area under the AFROC (Alternative Free-Response Receiver Operating Characteristics) curve also improved from 0.596 to 0.647 showing statistical significance.The subtraction image using this registration technique improves the diagnostic accuracy for subtle temporal changes.