Table 1.

Registration accuracy for variations of the CALIPER algorithm

	Cost function metrics					Landmark error (mm)			Atelectatic lobe DSC	Failure rate (%)
Registration	Healthy	Atelectasis	Label	VM	Reg	Mean	P90	Max
–	Unregistered					9.93	18.19	30.67	0.607	–
1	SSTVD	–	–	–	BE	4.31	10.63	25.54	0.648	6
2	SSTVD	SSTVD	–	–	BE	4.75	11.58	24.87	0.690	22
3	SSTVD	SSRVD	–	–	BE	4.81	11.57	24.84	0.699	22
4	SSTVD	SSD	–	–	BE	5.32	11.67	23.35	0.666	28
5	SSTVD	MI	–	–	BE	4.56	10.98	24.82	0.708	22
6	SSTVD	–	SSD	–	BE	2.78	6.03	23.16	0.891	6
7	SSTVD	SSTVD	SSD	–	BE	2.79	6.06	23.37	0.919	11
8	SSTVD	SSRVD	SSD	–	BE	2.80	6.09	23.42	0.919	11
9	SSTVD	SSD	SSD	–	BE	2.79	6.05	23.30	0.915	11
10	SSTVD	MI	SSD	–	BE	2.69	5.71	23.34	0.914	11
11	SSTVD	–	–	SSD	BE	4.57	11.39	27.29	0.631	11
12	SSTVD	SSTVD	–	SSD	BE	5.01	12.90	27.46	0.674	28
13	SSTVD	SSRVD	–	SSD	BE	4.78	11.65	25.70	0.705	22
14	SSTVD	SSD	–	SSD	BE	4.92	11.64	23.60	0.665	28
15	SSTVD	MI	–	SSD	BE	4.64	11.71	26.14	0.713	22
16	SSTVD	–	SSD	SSD	BE	2.58	5.35	22.35	0.877	6
17	SSTVD	SSTVD	SSD	SSD	BE	2.60	5.46	22.99	0.911	11
18	SSTVD	SSRVD	SSD	SSD	BE	2.61	5.52	23.01	0.912	11
19	SSTVD	SSD	SSD	SSD	BE	2.60	5.44	22.91	0.907	11
20	SSTVD	MI	SSD	SSD	BE	2.51	5.22	22.88	0.907	11

Healthy, lobes with healthy parenchyma; atelectasis, lobes containing atelectasis; label, lobe label image; VM, vesselness measure image; Reg, regularization penalty on the transformation; SSTVD, sum of squared tissue volume difference; SSD, sum of squared intensity difference; MI, mutual information; SSRVD, sum of squared regional volume difference; BE, bending energy penalty.