Table 1. Quantitative Image Analysis.

	40-keV Images	Conventional Images	P
CT attenuation of tumor (HU)	46.4 ± 8.4	34.6 ± 5.4	< 0.001
CT attenuation of WM (HU)	29.2 ± 4.9	26.2 ± 2.8	0.001
CT attenuation of GM (HU)	45.6 ± 5.4	34.4 ± 1.9	< 0.001
Image noise (HU)	5.5 ± 1.4	5.8 ± 1.2	0.03
Contrast of tumor-WM (HU)	17.3 ± 9.0	8.4 ± 5.5	< 0.001
Contrast of tumor-GM (HU)	0.8 ± 7.6	0.2 ± 5.4	0.47
CNR of tumor-WM	3.4 ± 1.9	1.5 ± 1.0	< 0.001
CNR of tumor-GM	0.2 ± 1.4	0.1 ± 0.9	0.31

Data are shown as mean ± standard deviation. CNR = contrast-to-noise ratio, GM = grey matter, HU = Hounsfield unit, WM = white matter