Fig. 2From: Neovascularization of hepatocellular carcinoma in a nude mouse orthotopic liver cancer model: a morphological study using X-ray in-line phase-contrast imagingMethod for calculating image contrast. a Four ROIs were labeled, and the two internal vessels were selected for calculating image contrast. Vessel boundaries were identified using a computer software (Image Pro Plus 6.0) that can identify both edges of a vessel (b) by expressing a density curve with a 256 gray-scale image (c)Back to article page