Absolutely.
Just edit the template and replace
{lang_top_images}
with an HTML <img> tag like this:
<img src="{template_url}/images/my_top_images.gif" border="0">
Alternatively, you can also edit your language file. Assuming english:
Open lang/english/main.php and replace:
$lang['top_images'] = "Top Images";
with something like this:
$lang['top_images'] = "<img src=\"{template_url}/images/my_top_images.gif\" border=\"0\">";
Take special note of how there is a backslash (\) character before the embedded double quote (") characters in the line. This method will replace all the occurrences of "Top Images" everywhere in the templates.
{template_url} will get replaced with the location of your templates so just upload the my_top_images.gif to your template's "images" directory.