Gallery_Remote:Protocol -> get thumbnail?

Hi,
I'm trying to develope an iPhone-gallery-client. Therefore I'm using the Gallery_Remote:Protocol. But is there any possibility to get the thumbnail from a picture which I selected with fetch-album-images? Look at this example please:

Thumb: http://p-4.ath.cx/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=143584
Image: http://p-4.ath.cx/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=143583

As you can see the thumbnail has another itemId So I can't use the itemId I got by the fetch-album-images request to get the thumbnail. Is that right? What can I do to solve the problem?

Br
Dennis