Diagnostic accuracy of dual-layer spectral computed tomography virtual monoenergetic imaging with multiplanar reformation for T-staging of colorectal cancer

Table 4 Intergroup comparisons of subjective and objective image quality parameters for 40-70 keV virtual monoenergetic images and polyenergetic images in colorectal cancer evaluation (n = 157)

Subjective/objective		PEIs	40 keV VMIs	50 keV VMIs	60 keV VMIs	70 keV VMIs
Noise	PEI	-	0.673	< 0.001	< 0.001	< 0.001
	40 keV VMIs	-	-	0.054	< 0.001	< 0.001
	50 keV VMIs	-	-	-	0.873	0.075
	60 keV VMIs	-	-	-	-	1.000
	70 keV VMIs	-	-	-	-	-
SNR	PEIs	-	< 0.001	< 0.001	< 0.001	< 0.001
	40 keV VMIs	-	-	< 0.001	< 0.001	< 0.001
	50 keV VMIs	-	-	-	< 0.001	< 0.001
	60 keV VMIs	-	-	-	-	< 0.001
	70 keV VMIs	-	-	-	-	-
CNR	PEIs	-	< 0.001	< 0.001	< 0.001	< 0.001
	40 keV VMIs	-	-	0.002	< 0.001	< 0.001
	50 keV VMIs	-	-	-	0.001	< 0.001
	60 keV VMIs	-	-	-	-	< 0.001
	70 keV VMIs	-	-	-	-	-
Subjective scores	PEIs	-	< 0.001	< 0.001	< 0.001	0.376
	40 keV VMIs	-	-	1.000	0.033	< 0.001
	50 keV VMIs	-	-	-	0.120	< 0.001
	60 keV VMIs	-	-	-	-	< 0.001
	70 keV VMIs	-	-	-	-	-

CNR: Contrast-to-noise ratio; SNR: Signal-to-noise ratio; PEI: Polyenergetic image; VMI: Virtual monoenergetic image.