Zend_Feed access item - ATOM

Iam trying to read the "itunes RSS Feed". As far as i know it is ATOM based.

Works fine:

    $feed = $this->getFeed(self::TOP300_PAYED);    foreach ($feed as $item) {        echo $item->name;    }

But i need the following node:

<im:image height="53">http://a3.mzstatic.com/us/r1000/116/Purple/61/9b/f2/mzl.wyuzxxzw.53x53-50.png</im:image>

any idea how to access this with zend feed??