contrast media in CT scan (x-rays, blood, vessels, tissue)

[kakye]

how does the contrast media can react with blood vessel to enhance the image?

[kronenborg]

the dye doesnt "react" with the blood - as the contrast passes from the blood vessels to organs which have taken up the dye, these tissues become less penetrable to x-rays, which then show up as a white signal on the ct scan.

basically the dye increases the visibility of the surfaces of the organ or tissue under investigation.