A Combined Pulmonary-Radiology Workshop for Visual Evaluation of COPD: Study Design, Chest CT Findings and Concordance with Quantitative Evaluation

Figures & data

Table 1.  Demographics of workshop subjects

	Normal non-smokers	Smokers without COPD	GOLD Stage 1	GOLD Stage 2	GOLD Stage 3	GOLD Stage 4
N	49	49	50	49	47	50
Age	62 ± 8	59 ± 9	64 ± 10	62 ± 9	66 ± 8	65 ± 8
Number (%) males	15 (31%)	28 (57%)	32 (64%)	25 (51%)	24 (51)%	25 (50%)
Smoking (pack years)	0	39 ± 23	49 ± 25	54 ± 24	58 ± 30	55 ± 23
FEV1 (% pred)	103 ± 13	97 ± 11	90 ± 6	65 ± 8	39 ± 6	22 ± 5
FEV1/FVC	0.79 ± 0.04	0.77 ± 0.05	0.65 ± 0.05	0.56 ± 0.07	0.43 ± 0.08	0.31 ± 0.07

Definition of abbreviations: FEV₁, forced expiratory volume in one second; FVC, forced vital capacity.

Normal non-smokers are subjects with FEV₁ >80% and FEV₁/FVC ratio >70% predicted and no history of lung disease.

Table 2.  Number of scans and readings in each group.

Review Group	Number of Scans	Number of reviewers	Number of Pulmonologists	Number of Radiologists	Total number of scans read
1	59	11	7	4	639
2	59	10	5	5	590
3	60	11	6	5	658
4	59	9	5	4	530
5	60	10	6	4	600
Total	297	51	29	22	3017

Table 3.  Kappa values for presence or absence of specific variables

Variable	Group 1	Group 2	Group 3	Group 4	Group 5
Emphysema	0.63	0.47	0.54	0.45	0.56
Panlobular emphysema	0.49	0.47	0.47	0.59	0.46
Centrilobular emphysema	0.38	0.25	0.30	0.35	0.35
Paraseptal emphysema	0.37	0.29	0.31	0.36	0.31
Bulla	0.36	0.28	0.37	0.3	0.22
Saber Sheath Trachea	0.36	0.25	0.44	0.39	0.36
Zone Distribution	0.29	0.24	0.26	0.25	0.29
Ground Glass attenuation	0.28	0.03	0.16	0.29	0.13
Bronchial wall thickening	0.24	0.23	0.17	0.27	0.24
Bronchial dilation	0.23	0.28	0.31	0.16	0.11
Tracheobronchomalacia	0.2	0.32	0.46	0.66	0.52
Gas trapping	0.17	0.19	0.2	0.19	0.23
Mucoid material in airways	0.09	0.25	0.17	0.38	0.35
Centrilobular nodules	0.08	0.1	0.13	0.2	0.08
Mosaic attenuation	0.08	0.02	0.02	0.14	0.13
Tracheobronchial Outpouching	0.08	–0.02	0.07	0.09	0.03
Bronchial dilation	0.02	0.22	0.09	0.21	0.16
Honeycombing/reticulation	0.02	0.01	0.12	0.24	0.13

Table 4.  Percentage of readings on which CT findings were identified, by disease category

	Total n	Total%	Normal non-smokers	GOLD 0	GOLD 1	GOLD 2	GOLD 3	GOLD 4	p*
Number of readings	3017	100%	509	500	510	509	489	500
Emphysema	1986	65.8%	20.4	44.2	69.6	76.6	86.3	98.8	< 0.0001
Panlobular emphysema	715	23.7%	1.0	2.2	10.4	20.8	41.7	66.2	< 0.0001
Centrilobular emphysema	1022	33.9%	4.9	13.2	37.6	40.3	51.9	66.0	< 0.0001
Paraseptal emphysema	1048	34.7%	6.5	28.4	42.2	45.2	40.3	47.2	< 0.0001
Bulla	483	16.0%	3.1	6.0	16.1	22.4	20.3	28.4	< 0.0001
Bronchial wall thickening	2006	66.5%	39.5	52.6	62.9	74.2	84.1	86.4	< 0.0001
Bronchial dilation	1502	49.8%	50.3	56.0	47.8	44.8	51.5	48.4	0.0122
Centrilobular nodules	975	32.3%	31.6	37.6	35.5	33.2	32.7	23.2	< 0.0001
Mosaic attenuation	382	12.7%	8.1	11.0	12.0	13.4	15.1	16.6	0.0007
Tracheobronchomalacia	499	16.5%	12.4	14.4	17.8	23.2	14.5	16.8	0.0034
Saber sheath trachea	330	10.9%	3.3	6.8	9.4	9.2	18.6	18.6	< 0.0001
Tracheobronchial outpouching	243	8.1%	7.3	7.0	7.3	6.7	9.0	11.2	0.0702
Mucoid material	248	8.2%	2.0	7.8	8.0	4.3	9.0	18.4	< 0.0001
Ground glass	294	9.7%	6.7	9.6	12.1	10.2	10.6	9.2	0.0887
Reticular/honeycombing	197	6.5%	3.3	5.2	8.0	6.3	7.4	9.0	0.0037
Gas trapping	2198	72.9%	57.1	58.0	69.6	74.1	86.5	93.4	< 0.0001

Data for each category are presented as% of readings on which finding was identified.

* chi-square (Pearson) test for difference in prevalence of abnormalities across categories.

Table 5(a).  Concordance between quantitative CT percentages of emphysema and visual evidence of emphysema

QCT% emphysema	Median visual score for emphysema
	Absent (n = 109)	Equivocal (n = 3)	Present (n = 182)
≤4.8%* (n = 112)	82 (75%)	2 (67%)	46 (25%)
>4.8% (n = 182)	27 (25%)	1 (33%)	136 (75%)
>10%	5 (5%)	1 (33%)	101 (55%)
>25%	1 (1%)	0	48 (26%)

* 4.8% was the 90th percentile for the% emphysema for 92 COPDGene normal subjects.

Kappa value for agreement for QCT and visual scoring was 0.48, and decreases to 0.20 when analysis is confined to the more normal subgroup (normal non-smokers, smokers without COPD and GOLD 1 subjects).

Table 5(b).  Concordance between quantitative CT and visual evidence of gas trapping on expiratory CT

QCT% gas trapping	Median visual score for gas trapping
	Absent (n = 63)	Present (n = 231)
≤19.5%*	63 (100%)	56 (24%)
>19.5%	0	175 (76%)
>25%	63 (100%)	150 (65%)
>50%	63 (100%)	76 (33%)

* 19.5% was the 90th percentile for the% gas trapping for 92 COPDGene normal subjects.

Kappa value for agreement for QCT and visual scoring was 0.58, and decreases to 0.40 when analysis is confined to the more normal subgroup (normal non-smokers, smokers without COPD and GOLD 1 subjects).

Table 5(c).  Concordance between quantitative CT and visual evidence of airway wall thickening

QCT% segmental wall area	Median visual score for bronchial wall thickening
	Absent (n = 79)	Equivocal (n = 8)	Present (n = 207)
≤ 60.9%*	62 (78%)	4 (50%)	78 (38%)
> 60.9%	17 (21%)	4 (50%)	129 (62%)

* 60.9% was the 90th percentile for segmental wall area% for 92 COPDGene normal subjects.

Kappa value for agreement for QCT and visual scoring was 0.33, and decreases to 0.22 when analysis is confined to the more normal subgroup (normal non-smokers, smokers without COPD and GOLD 1 subjects).

Figure 1.  (a) Axial CT image in a subject with GOLD Stage 1 COPD, where reviewers scored visual emphysema, but quantitative% of emphysema was less than 1%. CT shows mild centrilobular emphysema, which did not reach the quantitative threshold for emphysema. (b) Axial CT image in a subject with GOLD Stage 1 COPD where reviewers scored no visual emphysema, but quantitative% of emphysema was 18%. Close inspection shows multiple small foci of decreased attenuation adjacent to vessels which may either represent dilated peripheral airways or very early emphysema.

Figure 2.  Axial CT image in a non-smoking, physiologically normal subject, where reviewers scored visual gas trapping, but quantitative% of gas trapping was only 11%. CT shows relatively mild multilobular gas trapping, which did not reach the quantitative threshold for gas trapping.

Figure 3  (a) Axial CT image in a subject with GOLD Stage 1 COPD, where reviewers scored visual bronchial wall thickening, but wall area% of segmental bronchi was 55%. CT shows evidence of thickening of the bronchial walls, but associated moderate dilation of the bronchial lumens resulted in normalization of the wall area% value. (b) Axial CT image in a smoking control subject where reviewers scored no bronchial wall thickening, but wall area% of segmental bronchi was 63%. Although the bronchial walls appear visually normal, the bronchial lumens are relatively small, and this might have resulted in artificial elevation of the wall area% value.