Why is you maze not just in an array? surely that's the simpler solution, and forget about using images collide, simply go by the snapped location of the pacman?
ie
Then if your pacman is say 32x32 then just take the x,y pos take away the offset of where the maze is onscreen and divide by 32.
Anyway... That's how I'd do it..
ie
Dim Maze(9) Maze(0) = "XXXXXXXXX" Maze(1) = "X.......X" Maze(2) = "X.X.XXXXX" etc etc
Then if your pacman is say 32x32 then just take the x,y pos take away the offset of where the maze is onscreen and divide by 32.
Anyway... That's how I'd do it..