Difazio M C, MacMahon H, Xu X W, Tsai P, Shiraishi J, Armato S G, Doi K
Kurt Rossmann Laboratories for Radiologic Image Research, Department of Radiology, University of Chicago, IL 60637, USA.
Radiology. 1997 Feb;202(2):447-52. doi: 10.1148/radiology.202.2.9015072.
To improve early detection of disease in chest radiographs, the authors developed a digital processing technique that geometrically warps and subtracts a previous radiograph from a current radiograph to produce a temporal subtraction image. An observer test was performed to evaluate the effects of the temporal subtraction image technique on detection of interval change.
Fifty pairs of chest radiographs, including a baseline examination and a subsequent radiograph, were selected (25 cases in which potentially important new abnormalities had developed, and 25 in which there was no interval change). The baseline examination was chosen from multiple prior radiographs to minimize initial misregistration. By means of receiver operating characteristic (ROC) analysis, the ability of 11 observers to detect pathologic change when viewing the paired digitized baseline and subsequent radiographs was compared with their ability when viewing the same paired radiographs together with temporal subtraction images. Positive cases demonstrated focal new abnormalities that were greater than 1 cm in diameter.
The mean area (Az) under the ROC curves increased from 0.89 without to 0.98 with the temporal subtraction images. When the paired digitized previous and current chest radiographs were viewed in conjunction with the temporal subtraction images, a significant improvement in detection of new abnormalities was achieved (P = .00004), whereas the mean interpretation time was reduced by 19.3% (from 52 to 42 seconds, including the time to record the score and to move to the next case) (P = .0019).
The temporal subtraction technique can significantly improve sensitivity and specificity for detection of interval change in chest radiographs.
为了提高胸部X光片中疾病的早期检测率，作者开发了一种数字处理技术，该技术通过几何变形并从当前X光片中减去先前的X光片来生成时间减影图像。进行了一项观察者测试，以评估时间减影图像技术对检测间隔期变化的效果。
选择了50对胸部X光片，包括一次基线检查和随后的X光片（25例出现了潜在重要新异常的病例，以及25例无间隔期变化的病例）。从多张先前的X光片中选择基线检查片，以尽量减少初始配准误差。通过接受者操作特征（ROC）分析，比较了11名观察者在查看数字化的配对基线和后续X光片时检测病理变化的能力，以及他们在查看相同配对X光片并结合时间减影图像时的能力。阳性病例表现为直径大于1厘米的局灶性新异常。
ROC曲线下的平均面积（Az）从无时间减影图像时的0.89增加到有时间减影图像时的0.98。当结合时间减影图像查看数字化的先前和当前胸部X光片时，新异常检测有显著改善（P = .00004），而平均解读时间减少了19.3%（从52秒降至42秒，包括记录分数和进入下一个病例的时间）（P = .0019）。
时间减影技术可显著提高胸部X光片中间隔期变化检测的敏感性和特异性。
