Table 4.

Bias introduced by demons and B-splines deformable registration when forward and reverse image registrations were used.

	Demons			B-splines
	Forward bias (%)	Reverse bias (%)	Average bias (%)	Forward bias (%)	Reverse bias (%)	Average bias (%)
First-order features
Median	−0.11	0.50	0.20	−0.44	0.57	0.07
Mean	0.01	0.46	0.24	−0.27	0.57	0.15
70% quantile	−1.50	−1.38	−1.44	−0.50	0.18	−0.16
30% quantile	1.37	2.37	1.87	−0.36	1.06	0.35
Minimum	3.07	3.84	3.46	−3.62	−2.38	−3.00
Entropy (binned)	−3.86	−4.37	−4.12	−0.26	−0.02	−0.14
Entropy (unbinned)	−4.30	−5.24	−4.77	0.95	0.27	0.61
5% quantile	4.30	5.61	4.96	−0.07	1.80	0.87
Fractal features
Brownian dimension	−1.15	−1.42	−1.29	−0.09	−0.55	−0.32
Coarse dimension	−2.34	−3.09	−2.72	−0.06	−0.88	−0.47
Box-counting dimension	−5.49	−6.69	−6.09	−0.41	−2.24	−1.33
Laws’ filter features
E5L5 entropy	−2.16	−2.99	−2.58	0.25	−0.37	−0.06
S5L5 entropy	−3.26	−4.22	−3.74	0.22	−1.07	−0.43
R5L5 entropy	−3.53	−4.65	−4.09	−0.74	−3.47	−2.11
W5L5 entropy	−4.05	−4.86	−4.46	−0.07	−1.98	−1.03
GLCM features
Difference average	0.19	0.25	0.22	−4.12	−3.92	−4.02
Sum of squares variance	−0.29	−0.41	−0.35	−0.01	−0.18	−0.10
Sum average	−1.27	−1.28	−1.28	1.35	1.40	1.38
Sum variance	−2.52	−2.54	−2.53	2.73	2.83	2.78
Mean average bias	…	…	−1.50	…	…	−0.37
p1	…	…	…	…	…	0.15

¹Compared with average bias for demons registration.