Computational Biomedical Imaging Laboratory, Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Florence, Italy.
Acad Radiol. 2011 Nov;18(11):1403-11. doi: 10.1016/j.acra.2011.08.001.
To define a statistically based variation of individual whole-lung densitometry above which a real increase of pulmonary extent can be suspected in lung cancer screening trials.
Baseline and 3-month follow-up low-dose computed tomography (LDCT) examinations of 131 smokers or former smokers recruited in the ITALUNG (32 subjects) and MILD (99 subjects) trials were compared using for each data set two different image processing tools for whole-lung densitometry. Both trials were approved by institutional review boards, and written informed consent was obtained from all participants. Assuming that no change of emphysema extent can occur in a 3-month interval, the Bland and Altman method was used to assess the agreement between baseline and follow-up LDCT examinations for lung volume, 15th percentile (Perc15) of lung density and Perc15 corrected for lung volume by application of a linear detrend on log-transformed data.
Similar results were obtained in each data set using two different image processing tools. In the ITALUNG cohort the 95% limits of agreement (LoA) interval of volume corrected Perc15 was -9.7 to 10.7% using image processing method 1 and -10.3 to 11.5% using image processing method 2. In the MILD cohort, the 95% LoA interval of volume corrected Perc15 was -14.7 to 17.3% with both image processing methods.
In the two considered lung cancer screening settings a range of 9.7-14.7% decrease of volume corrected Perc15 represents a statistically defined threshold to suspect a real increase of emphysema extent in serial LDCT examinations.
定义一种基于统计学的个体全肺密度变化，以此来怀疑在肺癌筛查试验中肺部范围的真实增加。
对 131 名吸烟者或前吸烟者进行了基线和 3 个月的低剂量计算机断层扫描（LDCT）随访检查，这些吸烟者或前吸烟者分别来自 ITALUNG（32 例）和 MILD（99 例）试验。对于每个数据集，我们使用两种不同的全肺密度图像处理工具来比较基线和随访 LDCT 检查。这两个试验均获得了机构审查委员会的批准，并获得了所有参与者的书面知情同意。假设在 3 个月的时间间隔内肺气肿范围不会发生变化，我们使用 Bland 和 Altman 方法来评估基线和随访 LDCT 检查在肺容量、15 百分位数（Perc15）和 Perc15 校正肺容量之间的一致性，该校正应用了对数转换数据的线性去趋势。
使用两种不同的图像处理工具在每个数据集上均得到了相似的结果。在 ITALUNG 队列中，使用图像处理方法 1 的体积校正 Perc15 的 95%置信区间（LoA）为-9.7 至 10.7%，使用图像处理方法 2 的为-10.3 至 11.5%。在 MILD 队列中，两种图像处理方法的体积校正 Perc15 的 95%LoA 区间均为-14.7 至 17.3%。
在这两个考虑的肺癌筛查环境中，体积校正 Perc15 降低 9.7-14.7%的范围代表了在连续 LDCT 检查中怀疑肺气肿范围真实增加的统计学定义阈值。
