Feasibility and potential benefits of defining the internal gross tumor volume of hepatocellular carcinoma using contrast-enhanced 4D CT images obtained by deformable registration

Table 1 A comparison of GTVs obtained from 3D and 4D CT scans in different breathing phases before and after DR ( $\overset{s}{x}$ (_x ± S)

Scan/phase		GTV before DR (cm³)	GTV after DR (cm³)	t	P
3D CT_CE		20.92±13.20	_	_	_
3D CT_NCE		15.52±11.86	_	_	_
4D CT_NCE	CT₀₀	15.03±12.74	20.82±13.41	-3.61	0.006
	CT₁₀	14.84±12.66	20.81±13.65	-3.74	0.005
	CT₂₀	14.72±13.11	20.72±13.66	-3.74	0.005
	CT₃₀	14.94±13.14	20.68±13.70	-3.79	0.004
	CT₄₀	14.93±12.70	20.62±13.24	-3.65	0.005
	CT₅₀	15.66±12.13	20.48±13.13	-4.22	0.002
	CT₆₀	15.17±11.76	20.41±13.25	-3.62	0.006
	CT₇₀	15.03±11.87	20.45±12.71	-4.19	0.002
	CT₈₀	15.43±12.78	20.57±13.36	-3.48	0.007
	CT₉₀	15.50±13.23	20.65±13.36	-3.17	0.011
F		8.17	15.319	_	_
P		0.002	0.000	_	_

DR: deformable registration; CE: contrast enhancement; NCE: non-contrast enhancement; CT_x: respiration phase.

ISSN: 1748-717X