Find image in SSRS via Javascript

Hi

I know you can do the following to find any related tags:

var el = document.getElementsByTagName('span');
if(el[nr].innerHTML=="SPAN")

Inserting 'IMG' obviously finds all images but I need to find my image with its name. So if I put an image on my report and named it iMyImage and it's embedded how do I find iMyImage? I need to do a mouseover event on the image. It works perfectly with placeholder SPAN in textbox but I can't find my image to do the mouseover on.

Thanks

Sunette