. Author manuscript; available in PMC: 2010 Sep 22.

Published in final edited form as: Acad Radiol. 2009 Jun;16(6):689–699. doi: 10.1016/j.acra.2008.12.024

Table 3.

Reproducibility of lung density measures from pairs of cardiac CT scans at baseline and at follow-up.

	Paired Cardiac CT Scans at Baseline (n=119 participants)				Paired Cardiac CT Scans at Follow-up (n=118 participants)

	Spearman's correlation coefficient	Mean difference (95%CI)	Intraclass correlation coefficient^*	95% limits of agreement	Spearman's correlation coefficient	Mean difference (95% CI)	Intraclass correlation coefficient^*	95% limits of agreement
%emphysema_{-910 HU}	0.92	0.05 (-0.71, 0.81)	0.93	-8.28, 8.38	0.93	0.41 (-0.66, 1.48)	0.89	-11.2, 12.0
Alpha_{-910 HU}	0.91	-0.012 (-0.04, 0.01)	0.88	-0.31, 0.28	0.93	-0.03 (-0.05, -0.008)	0.91	-0.28, -0.22
Apical-basilar difference in %Emphysema_{-910 HU}	0.82	0.05 (-0.63, 0.74)	0.84	-7.40, 7.50	0.76	0.85 (-0.15, 1.84)	0.70	-9.98, 11.7
Apical-basilar difference in alpha_{-910 HU}	0.71	-0.006 (-0.05, 0.04)	0.68	-0.46, 0.45	0.68	-0.003 (-0.05, 0.04)	0.64	-0.50, 0.50

Intraclass correlation coefficient = between-person variance/(between-person variance + within-person variance)