Kalender W A, Fichte H, Bautz W, Skalej M
Siemens Medical Systems, Erlangen, F.R.G.
J Comput Assist Tomogr. 1991 Mar-Apr;15(2):248-55. doi: 10.1097/00004728-199103000-00011.
Accuracy, reproducibility, and objectivity are important in quantitative assessment of lung density and structure by CT, and the measurement has to be carried out under tightly controlled conditions. We therefore employ respiratory gating at defined levels of inspiration for CT scanning. In the evaluation process, we found operator-induced errors of 2-6 HU standard deviation for the relatively simple task of global lung density estimates; in regional evaluations, they frequently exceeded 10 HU. We therefore developed semi-automated evaluation algorithms that isolate lung parenchyma by fast contour tracking and define subregions by shrinking, radial segmenting, and anteroposterior subdividing of the left and the right lung. Global and regional mean density values and histogram parameters were extracted. Based on our clinical studies, we estimate that an overall precision of better than 5% can be achieved in quantitative CT of the lung with cooperative patients.
在通过CT对肺密度和结构进行定量评估时，准确性、可重复性和客观性至关重要，并且测量必须在严格控制的条件下进行。因此，我们在特定的吸气水平采用呼吸门控进行CT扫描。在评估过程中，我们发现对于相对简单的全肺密度估计任务，操作人员会导致2-6HU标准差的误差；在区域评估中，误差经常超过10HU。因此，我们开发了半自动评估算法，通过快速轮廓跟踪分离肺实质，并通过对左右肺进行收缩、径向分割和前后细分来定义子区域。提取全肺和区域平均密度值以及直方图参数。基于我们的临床研究，我们估计，对于配合良好的患者，肺部定量CT可以实现优于5%的整体精度。
