jasne, nesmis pouzit

a {
background-image: url('obr1.jpg');
width: 100px;
height: 20px;
}
a:hover {
background-image: url('obr2.jpg');
}

ale

a.odkaz:link {
background-image: url('obr1.jpg');
width: 100px;
height: 20px;
}
a.odkaz:hover {
background-image: url('obr2.jpg');
}

a pak

<a class="odkaz" href="odkaz.nekam.html"></a>