Smooth call, raise or push?

[utmt40]

1166 entries 5+.50 buy in down to final two tables. UTG is pretty loose and I have seen him raise/re raise 3 of the 5 hands we have played together to this point. Do you smooth call here, raise or push? Why?

PokerStars No-Limit Hold'em Tourney, Big Blind is t6000 (9 handed) converter

MP3 (t8560)
Hero (t83854)
Button (t163464)
SB (t51824)
BB (t263588)
UTG (t108631)
UTG+1 (t41910)
MP1 (t28360)
MP2 (t33100)

Preflop: Hero is CO with A[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/club.gif[/img].
<font color="#CC3333">UTG raises to t18000</font>, <font color="#666666">4 folds</font>, <font color="#CC3333">Hero????