Android : Image border-radius

Im creating android application with the help of ionic famework. Im having this problem with the UI. Im using lists in ionic to show the today's deals given by the shops.

Im making the thumbnails as round by the property border-radius:100% , but when a rectangle image is placed my avatar is messed up. Find the picture below

I want to get my thumbnails round in shape without being stretched. Image of expected list is given below

Is there any way to make the avatar in ionic framework as round ?

<div class="list">

    <!--.....................loop........................................................-->
            <a class="item item-icon-right item-thumbnail-left" href="#">

                <img style="border-radius: 100%;"  src="img/sample.jpg">
                <h2>HEADINGG</h2>
                <p>Details : Hey guys i saw that there was no thread for p300, so i decided to make one (this is the support and development thread) Do this at your own risk 1=Root your funbook It is rooted but sometimes it is not rooted so you must visit this page</p>
                <i class="icon ion-chevron-right stable"></i>
            </a>            
    <!--.....................loop........................................................-->    
        </div>

I think i have to do something with the CSS . I dont know what to do.