Center for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, UCLA, 924 Westwood Blvd., Ste. 615, Los Angeles, CA, USA.
Eur Radiol. 2012 Feb;22(2):287-94. doi: 10.1007/s00330-011-2277-1. Epub 2011 Oct 20.
The reproducibilities of CT lung volume and densitometric measures of emphysema were assessed over 1 week. The influence of breathhold on reproducibility was assessed.
HRCT was performed on 44 subjects at inspiration on two visits with a 7-day interval. CT lung volume, relative area below -950HU (RA950-raw), and 15th percentile density (PD15-raw) were computed. Volume correction was used to obtain RA950-adj and PD15-adj. Reproducibilities between visits were assessed using concordance correlation coefficient (CCC) and repeatability coefficient (RC). Reproducibilities were compared between raw and adjusted measures. Differences between visits were computed for volume and density measures. Correlations were computed for density differences versus volume difference. Subgroup analysis was performed using a 0.25 L volume difference threshold.
High CCC were observed for all measures in full group (CCC > 0.97). Reproducibilities of volume (RC = 0.67 L), RA950-raw (RC = 2.3%), and PD15-raw (RC = 10.6HU) were observed. Volume correction significantly improved PD15 (RC = 3.6HU) but not RA950 (RC = 1.7%). RA950-raw and PD15-raw had significantly better RC in <0.25 L subgroup than ≥0.25 L. Significant correlations with volume were observed for RA950-raw and PD15-raw (R (2) > 0.71), but not RA950-adj or PD15-adj (R (2) < 0.11).
Good breathhold and RA950 reproducibilities were achieved. PD15 was less reproducible but improved with volume correction or superior breathhold reproduction.
• Good breath-hold reproducibility is achievable between multiple CT examinations. • Reproducibility of densitometric measures may be improved by statistical volume correction. • Volume correction may result in decreased signal. • Densitometric reproducibility may also be improved by achieving good breath-hold reproduction. • Careful consideration of signal and noise is necessary in reproducibility assessment.
评估 CT 肺容积和肺气肿密度计量测量的可重复性，时间跨度为 1 周。评估屏气对可重复性的影响。
对 44 名受试者在两次访问时分别进行吸气 HRCT，两次访问间隔为 7 天。计算 CT 肺容积、低于 -950HU 的相对面积（RA950-raw）和 15 百分位数密度（PD15-raw）。使用体积校正获得 RA950-adj 和 PD15-adj。使用一致性相关系数（CCC）和重复性系数（RC）评估两次访问之间的可重复性。比较原始和调整后的测量值的可重复性。计算体积和密度测量值之间的差异。计算密度差异与体积差异之间的相关性。使用 0.25 L 体积差异阈值进行亚组分析。
所有测量值在全组中均表现出较高的 CCC（CCC>0.97）。观察到体积（RC=0.67 L）、RA950-raw（RC=2.3%）和 PD15-raw（RC=10.6HU）的可重复性。体积校正显著改善了 PD15（RC=3.6HU），但对 RA950 无影响（RC=1.7%）。在<0.25 L 亚组中，RA950-raw 和 PD15-raw 的 RC 明显优于≥0.25 L。RA950-raw 和 PD15-raw 与体积有显著相关性（R (2) >0.71），而 RA950-adj 或 PD15-adj 无相关性（R (2) <0.11）。
实现了良好的屏气和 RA950 可重复性。PD15 的可重复性较差，但通过体积校正或更好的屏气复制可得到改善。
