Using In_Array with Query Results

[eluser]lightnb[/eluser]
How can I do this?

Code:

$this->db->select('ForumCategoryName, ForumCategoryType');
$Query = $this->db->get('Forums_Categories');
$ResultArray = $Query->result();

if(in_array($CategoryName, $ResultArray['ForumCategoryName']))
{
...

I want to see if "$CategoryName" is one of the "ForumCategoryName"s found by the query.