Table 4.

The TRE comparison for the MR-to-CT synthesis and the overall registration.

MR-to-CT Synthesis (crMR-sCT)
Methods	CycleGAN (31)	MUNIT (32)	SPSNet (ours)
TRE/mm	6.70 ± 4.22	4.03 ± 2.81	2.93 ± 1.75
	(95% CI: 5.78–7.62)	(95% CI: 3.41–4.65)	(95% CI: 2.55–3.31)
Overall Registration (MR-CT)
Methods	ANTs (33)	ANTs (33) + SPSNet	ANTs (33) + SPSNet + RRS (ours)
TRE/mm	13.56 ± 8.41	8.06 ± 4.98	3.67 ± 2.43
	(95% CI: 11.72–15.40)	(95% CI: 6.97–9.15)	(95% CI: 3.14–4.20)

RRS, Refined registration submodule. TRE values are reported as mean ± standard deviation, with 95% confidence intervals shown in parentheses. In the synthesis process, a lower TRE indicates a smaller spatial gap between the same landmark in the synthesized and real images. For the overall registration, lower TREs indicates better registration results.

Bold values indicate the lowest registration error in each row.