Table 1.

Estimated number of artifacts detected with convex transducer (3.5–5 MHz) during intercostal US scans in the two groups.

Artifact	Operatora	Healthy subjects (Estimated Mean)b	Pneumonectomy patients (Estimated Mean)b	p-valuea
Comet-tail	Operator 1	2.25	2.28	0.28
	Operator 2	2.05	2.10	0.19
Ring-down	Operator 1	1.95	1.91	0.10
	Operator 2	1.85	1.89	0.20
Simple reverberation	Operator 1	3.40	3.38	0.56
	Operator 2	3.37	3.37	0.79
Total Artifacts	Operator 1	7.60	7.57	0.59
	Operator 2	7.26	7.37	0.10

^aOperator 2 was blinded to the group origin of the scan.

^bEstimated means for the healthy subjects versus pneumonectomy patients (Poisson regression models).