I think that honestly, the best way to prepare for this is to know the major images (SAH, epidural bleed, masses/AAA on CT). I got ridiculous pictures that many times had nothing to do with the question. I got the same gross dissection of a kidney for 3 separate questions in 3 separate blocks and the picture was not necessary for the question each time. One was a cross sectional drawing of a 4 day old embryo with a question about embryologic derivation, but it was a pic I had never seen before anyway.
With that said, webpath is a pretty good resource, although I didnt find the graphic questions too challenging.