Lost the references of images I added in PowerPoint

I had added several similar looking images in the slides. The differences between the images are very minute and only after my explanation the audience will be able to find that. But, for my bad luck, I have lost the references. I mean, I have about 12 images in a slide and even I am unsure of the progression. Which comes after what? I have a doubt that I may have misplaced them but now, I cannot verify it just to cross check. One way is to do all the slides again! Is there a way to find the file name of the picture I have added in the slide? If I get the file name of the picture back, it will be helpful.