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

Table 4 Receiver operator characteristic analysis of spectral parameters in differentiating Ki-67 low expression status from high expression status

		AUC (95%CI)	TV	YI	Sen (%)	Spe (%)	PPV (%)	NPV (%)	Acc (%)
AP	Zeff	0.759 (0.668, 0.836)	≤ 8.27	0.67	85.92	81.08	92.96	37.84	71.30
	nZeff	0.796 (0.707, 0.867)	≤ 0.74	0.67	80.28	86.49	85.92	54.05	75.00
	IC	0.752 (0.660, 0.830)	> 1.63	0.60	78.87	81.08	88.73	21.62	65.74
	nIC	0.773 (0.683, 0.848)	> 0.16	0.61	74.65	86.49	81.69	48.65	70.37
VP	CT40 kev	0.630 (0.531, 0.721)	≤ 271.2	0.26	80.28	45.95	95.77	24.32	71.30
	CT70 kev	0.631 (0.533, 0.722)	≤ 138.8	0.31	92.96	37.84	94.37	32.43	73.15
	CT100 kev	0.662 (0.565, 0.750)	≤ 89.3	0.28	81.69	45.95	87.32	32.43	68.52
	Zeff	0.777 (0.687, 0.851)	≤ 8.75	0.73	88.73	83.78	92.96	29.73	74.07
	nZeff	0.835 (0.751, 0.899)	≤ 0.83	0.68	78.87	89.19	85.92	51.35	74.07
	IC	0.747 (0.654, 0.826)	> 2.65	0.63	84.51	78.38	85.92	27.03	65.74
	nIC	0.805 (0.718, 0.875)	> 0.43	0.71	78.87	91.89	85.92	37.84	69.44
Multi-parameters		0.967 (0.913, 0.992)	-	0.88	95.77	91.89	97.18	86.49	93.52

AUC: Area under the curve; TV: Threshold value; YI: Youden index; Sen: Sensitivity; Spe: Specificity; NPV: Negative predictive value; PPV: Positive predictive value; Acc: Accuracy; Z^eff_AP and Z^eff_VP: The effective atomic number in the arterial and venous phase; nZ^eff_AP and nZ^eff_VP: The normalized effective atomic number in the arterial and venus phase; IC_AP and IC_VP: The iodine concentration in the arterial and venous phase; nIC_AP and nIC_AP: The normalized iodine concentration in the arterial and venous phase; 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.