OCR for Line Drawings?

MIT Press has kindly given me permission to put my first book, Practical Parallel Programming, up on the web. Many of the specifics are out of date, but I think (at least, I hope) much of the discussion is still useful.

One problem, though: nobody has the electronic source for the book’s hundred or more diagrams. I spent a couple of weeks sketching them with a pencil and straight edge in the VU library in the summer of 1994; a graphic artist in Boston then re-drew them using a Mac, but those files are long gone. I could chop a copy of the book and scan what I need as PNGs, but it got me wondering about OCR software for vector images. If anyone can recommend something, I’d welcome a pointer.