Monochromatic energy computed tomography image for active intestinal hemorrhage: A model investigation

Table 1 Comparison of detection rates for the region of contrast agent exudation between spectral computed tomography and multidetector row computed tomography in different phases

Grouping	Detection result		Total	Detection rate	χ2	P value
	Detected	Not detected
64-slice CT in the AP	23	12	35	65.71%	5.185	0.023
spectral CT in the AP	31	4	35	88.57%
64-layer CT in the PVP	32	3	35	91.43%	1.3931	0.238
spectral CT in PVP	35	0	35	100.00%

¹Represent χ² correction. 64-layer computed tomography (CT) in arterial phase (AP) and portal venous phase (PVP), χ² = 6.873, P = 0.009; spectral CT in AP and PVP, χ² corrected = 2.386, P = 0.122.

Table 2 Comparison of contrast to noise ratios values of the exudation regions at each energy level and blood flow rate between portal venous phase and arterial phase

	PVP	AP	t	P value
40 keV	19.35 ± 10.89	7.69 ± 6.68	-2.4151	0.036
50 keV	20.82 ± 11.26	8.78 ± 7.21	-2.380	0.035
60 keV	20.63 ± 10.07	8.83 ± 6.75	-2.575	0.024
70 keV	15.65 ± 8.17	5.93 ± 4.46	-2.762	0.017
80 keV	10.46 ± 5.83	3.44 ± 2.41	-2.945	0.012
90 keV	7.33 ± 3.92	2.31 ± 1.52	-3.157	0.008
100 keV	5.83 ± 2.70	1.49 ± 1.01	-3.996	0.004
Mixed-energy image	11.68 ± 6.38	3.58 ± 2.09	-3.189	0.015
F	18.298	7.823
P value	0.000	0.000

¹Using Satterthwaite’s approximate t test. No significant difference between 40, 50, 60 and 70 keV in the portal venous phase (PVP), but the difference was significant when compared with the polychromatic energy imaging (P < 0.05). No significant difference between 40, 50 and 60 keV in the arterial phase (AP), but the difference was significant when compared with the polychromatic energy imaging (P < 0.05).

Table 3 Comparison of image quality scores at each energy level and blood flow rate between portal venous phase and arterial phase

	PVP	AP	t	P value
40 keV	4.63 ± 0.58	3.46 ± 1.43	1.9991	0.081
50 keV	4.46 ± 0.65	3.06 ± 1.20	2.724	0.018
60 keV	4.20 ± 0.77	2.97 ± 1.26	2.195	0.049
70 keV	3.54 ± 0.91	2.23 ± 0.92	2.692	0.020
80 keV	3.00 ± 0.83	1.97 ± 0.87	2.263	0.043
90 keV	2.46 ± 0.55	1.49 ± 0.49	3.494	0.004
100 keV	2.26 ± 0.54	1.09 ± 0.11	5.6501	0.001
Mixed-energy imaging	3.60 ± 1.13	2.46 ± 1.06	1.953	0.074
F	52.549	19.875
P value	0.000	0.000

¹Using Satterthwaite's approximate t test. There was no significant difference between 40, 50 and 60 keV in the portal venous phase (PVP), but the difference was significant when compared with the polychromatic energy imaging (P < 0.05). There was no significant difference between 40, 50 and 60 keV in the arterial phase (AP), but the difference was significant among other energy levels (P < 0.05).