IE, download image without using the src/url

Hello,
i'm using IE to browse some pages and i need to download an image <img src=" .... ">
the problem is that the image changes every time you acess the server which means InetGet on the url of the image won't work.
i've thinked about using javascript injection or memread but i've never done this before and i have no clue on how to do it.
Thanks for your help