Is there a way I can check a variable exists AND its value?

Question

Is there a better way, in PHP, to both check that this variable exists and if it does, check its value?

Right now, I'm doing a lot of this nonsense - checking first if something exists, and then checking what the value is. There must be an easier way, but I don't quite know how to do it.

  if (isset($podcast['contentAdvisoryRating'])) {
    if ($podcast['contentAdvisoryRating']=='Explicit') {
      echo '<B>EXPLICIT</B><BR>';
    }
  }