Let us know what the build is for!
All in all I dont like shatter without Frostbite. With Frostbite I think it's a much better ability. Either way Shatter is not for raids/instances, so keep that in mind.
I dont like Improved Mana shield, so i suppose you can take the points from there and put them into Frostbite. I also prefer Mind mastery to Imp CoC/Arctic Reach, but since that would leave you at 37/0/24 if you do spec into Frostbite, you may want to just stick with 33/0/28.
I was 40/0/21 with Shatter and no Frostbite and I didnt like it at all (not as mana-efficient and 1 Shatter per encounter in PvP and world PvE didnt seem worth it for the lack of instance viability for those points)... I decided to go with Elemental Precision/Frost Channeling instead.