If you follow the tutorial How to add a custom font in a theme you can add Font Awesome. Then instead of an image you can add a font icon using CSS like this...
.block .header .title h2:after {
color: #FFFFFF;
display: block;
float: right;
font-family: FontAwesome;
font-size: 1.2em;
height: 20px;
margin: 0;
padding: 0;
text-align: center;
width: 20px;
}
.block .header .title h2:after {
background-color: #000;
content: "\f19d";
margin-left: 5px;
}