Seltzer S E, Judy P F, Feldman U, Scarff L, Jacobson F L
Department of Radiology, Harvard Medical School, Boston, MA 02115, USA.
Radiology. 1998 Mar;206(3):617-22. doi: 10.1148/radiology.206.3.9494475.
To evaluate the effect of reducing image size on observers' ability to detect lung nodules on computed tomographic (CT) scans.
Stimuli were 80 single sections from 13 normal chest CT studies. On half of the images, 3-5-mm-diameter nodules were superimposed electronically at random locations. Four observers viewed images in six formats and sizes that ranged from 6 on 1 (133 x 133 mm) to 80 on 1 (40 x 40 mm). The images were viewed at a fixed distance of 55 cm and at an unrestricted, variable distance.
With the fixed viewing distance, nodule detection decreased with smaller image sizes. The area under the receiver operating characteristic curve (Az) decreased from 0.857 for the 6-on-1 format to 0.671 for the 80-on-1 format (P = .0001). With a variable viewing distance, Az decreased from 0.884 to 0.834 across all formats (difference not statistically significant). However, there was a significant drop in performance with the smallest images (P < .05). Overall, Az for the fixed and variable viewing distances was significantly different (P < .001).
Reducing image size leads to decreased lung nodule detection on CT scans viewed at a fixed distance; however, the observer can compensate for the smaller image by adjusting the viewing distance.
评估缩小图像尺寸对观察者在计算机断层扫描（CT）上检测肺结节能力的影响。
刺激物为来自13项正常胸部CT研究的80个单层面图像。在一半的图像上，随机位置以电子方式叠加了直径3 - 5毫米的结节。四名观察者以六种格式和尺寸查看图像，范围从1幅图像显示6个视野（133×133毫米）到1幅图像显示80个视野（40×40毫米）。图像在固定距离55厘米处以及不受限制的可变距离处查看。
在固定观察距离下，结节检测随着图像尺寸变小而降低。接受者操作特征曲线下面积（Az）从1幅图像显示6个视野格式的0.857降至1幅图像显示80个视野格式的0.671（P = 0.0001）。在可变观察距离下，所有格式的Az从0.884降至0.834（差异无统计学意义）。然而，最小图像的检测性能有显著下降（P < 0.05）。总体而言，固定和可变观察距离下的Az有显著差异（P < 0.001）。
缩小图像尺寸会导致在固定距离查看CT扫描时肺结节检测能力下降；然而，观察者可以通过调整观察距离来补偿较小的图像。
