The generator matrix

 1  0  0  0  1  1  1 3X+2  1  X  1  0  1 2X+2  0 2X  1  1
 0  1  0  0  X 2X+1 3X+3  1 2X  1 X+1 3X X+1  1 3X+2  1  3  0
 0  0  1  0 X+1  1  X X+1 3X+3  X 3X+2  1 2X+1 X+1  2  3 2X+1  0
 0  0  0  1  1 2X+2 X+1 X+1 2X+2 3X+3  X X+3 2X+1  0  1 X+2 3X+2  0
 0  0  0  0 2X+2 2X  0  0 2X+2 2X+2 2X+2 2X 2X 2X+2  2  0 2X 2X

generates a code of length 18 over Z4[X]/(X^2+2X+2) who´s minimum homogenous weight is 12.

Homogenous weight enumerator: w(x)=1x^0+78x^12+558x^13+2284x^14+8740x^15+26677x^16+56058x^17+73062x^18+56600x^19+26558x^20+8578x^21+2312x^22+516x^23+94x^24+22x^25+6x^26

The gray image is a code over GF(2) with n=144, k=18 and d=48.
This code was found by Heurico 1.16 in 91.4 seconds.