function extractBetween($string, $begin, $end){
		if ( false === ($string = strstr($string, $begin)) ){
			return false;
		}

		if ( false === ($endPos = strpos($string, $end)) ){
			return false;
		}
		
		return substr($string, 0, $endPos);
	} # end function

$content = "<!--Start-->
Test<br />
Test<br />
Test
<!--End-->Test";

echo extractBetween($content, '<!--Start-->', '<!--End-->');