Quantitative parameters in novel spectral computed tomography: Assessment of Ki-67 expression in patients with gastric adenocarcinoma

Table 3 Comparison of dual-layer spectral detector computed tomography-derived parameters between low and high Ki-67 expression status

	Parameters	Low Ki-67 status	High Ki-67 status	t value	P value
AP	CT40 kev	177.3 ± 43.9	162.3 ± 37.8	1.85	0.068
	CT70 kev	90.9 ± 20.1	85.5 ± 16.6	1.48	0.141
	CT100 kev	63.8 ± 12.7	61.7 ± 12.6	0.81	0.422
	λHU	2.88 ± 1.04	2.56 ± 0.98	1.58	0.118
	Zeff	8.30 ± 0.19	8.21 ± 0.10	2.87	0.006
	nZeff	0.78 ± 0.04	0.74 ± 0.03	5.33	< 0.001
	IC (mg/mL)	1.61 ± 0.15	1.73 ± 0.19	-3.53	0.001
	nIC	0.15 ± 0.02	0.19 ± 0.04	-5.88	< 0.001
VP	CT40 kev	265.9 ± 61.4	237.3 ± 45.8	2.50	0.016
	CT70 kev	126.5 ± 33.4	108.0 ± 20.9	3.07	0.003
	CT100 kev	84.3 ± 18.7	73.9 ± 17.2	3.71	0.005
	λHU	4.65 ± 1.43	4.31 ± 1.15	1.33	0.185
	Zeff	8.75 ± 0.24	8.62 ± 0.15	3.04	0.004
	nZeff	0.87 ± 0.04	0.83 ± 0.03	6.59	< 0.001
	IC (mg/mL)	2.62 ± 0.17	2.75 ± 0.21	-3.40	0.001
	nIC	0.41 ± 0.04	0.46 ± 0.06	-5.87	< 0.001

CT_{40 kev}, CT_{70 kev} and CT_{100 kev}: The computed tomography attenuation values of at 40 kilo electron volt (kev), 70 kev and 100 kev respectively; λ_HU: The slope of the spectral curve; Z^eff: Effective atomic number; nZ^eff: The normalized effective atomic number; IC: Iodine concentration; nIC: Normalized iodine concentration; AP: Arterial phase; VP: Venous phase.