There were no significant difference of image quality including SNR and CNR of aortic root ( AO ) , left main coronary artery ( LM ) , left anterior descending artery ( LAD ) , circumflex coronary artery ( CX ) and right coronary artery ( RCA ) Between A and B group ( P = non-significant for all comparison ) , whereas Iodine in taken of A group decreased 14 % ( 17 600 mg vs 20 350 mg ) .