In my unordered list, I use an image for the bullet but the bullet appears aligned with the bottom of the text to the right of it. I would like to have it positioned in the middle of the text's height. Is there some way in css to center or add an offset to the bullet?

<ul>
  <li>item 1</li>
  <li>item 2</li>
</ul> 
ul
{
  list-style-image: url('/images/bullet_blue_8x8.png');
}

thanks in advance