The original Lenna image is still copyrighted and will remain so for a while (even if right now Playboy Enterprises, Inc. has decided to not sue people over its use in research) and people can't seem to agree on a standard replacement [1].

Since that is the case, how about a Kickstarter campaign to recreate the 512x512 image as close a possible and distribute the imitation under a free license? I.e., you could hire a professional model (by running a Lenna double contest online?) and a pro photographer, recreate the environment and the props, etc. Keep it clean (no remaking the full nude) and you could get free press and support from the researchers themselves.

[1] Though you can find links to a good number of alternative image sets at https://en.wikipedia.org/wiki/Standard_test_image.