Premiere Elements is a video editor, so it is impossible to load photos into it and maintain their high resolution. Your photos, as with the rest of the video, will be either 720x480 pixels (standard resolution) or 1920x1080 (high resolution). DVDs are standard resolution and BluRay discs are high resolution.
In fact, as I say in my books, you'll get the best results if the photos you add to your video are no larger than 1000x750 for standard resolution or 2000x1500 high rez.
If you want to create a slideshow that maintains your photos' detail, you should look into a program like Pro Show Gold. Its slideshows can only be viewed on a computer, however -- since your TV itself is only 720x480 or, if it's an HDTV, 1920x1080.
As Steve points out, both DVD-Video and BD, are limited in pixel x pixel dimensions. When one views their Mega-pixel Images on a high-rez monitor, they DO look very good, sharp and with excellent dynamic range (especially if shot in say 16-bit Color Depth). Then, when they are Scaled down to either the SD 720 x 480 (NTSC) DVD-Video Frame Size, or even the HD 1920 x 1080 BD Frame Size, they have lost much of their original resolution. This is especially noticable, if one is going to DVD-Video, and then viewing on a high-rez monitor, like the computer's screen, or an HD TV. That is the nature of the beast. When the DVD-Video specs. were written, they were a great improvement over VHS tapes, which were the preferred medium of that day. People marveled over the quality of the DVD-Videos, but that was then. BD was a marked improvement, basically upping the resolution 4x. Still, even it is limited, compared to a 16 MP Image.
The best that one can do is to Scale the Images down to the Frame Size of the Project, in Photoshop, or Photoshop Elements (both have better Scaling algorithms, than does Premiere Elements, plus also offer more control over exactly which Scaling algorithm is used), Import those Images, place them onto the Timeline, and Render it, by hitting Enter/Return, for best playback. Last, burn the Project to a high-quality blank disc, say Falcon Pro, Verbatim or Taiyo-Yuden, using the highest Bit-Rate possible (within the DVD, or BD specs.), for the Duration of the Project. In PrE, this means about 120 mins. of Duration, at Highest Quality.
With DVD-Video, there IS one other factor, that can positively affect the playback on an HD TV, and that is to play the disc on either a late model up-rezzing DVD player, or BD player. Those players have chips that are designed to up-rez the signal, and they do an amazing job. By using such a player, the DVD-Videos will be even better, but still far short of what the HD BD can provide - still better enough to show. Since those chips are dedicated to do one job, up-rezzing, what one sees then, will be as good as it will ever get.
I faced the same dilemma, when I started doing Web design. I was coming from an advertising photographic background, where my clients were doing very high-resolution 6 to 8 color printing, and suddenly, I was faced with Images going onto a computer screen (640 x 480 back then). My beautiful Images looked like ca-ca. Same with the type that I had to use. Frustrating, but such is life. Then, when I started shooting for production to DVD-Video, I was faced with the same quality issues. My beautiful 12 MP 16-bit Images looked like "snapshots." Just as frustrating, and something that I had to learn to live with. Now, BD is better (about 4x better), but still far short of my original Images.
Good luck, and being a photographer, I feel your pain.