I Have A 6 Month Old Son Very Normal Was

I have a 6 month old son very normal was born with small diple that dr said do not worry about so fare is okey. Went to pediatition fx of sacral dimple rec x Ray the radiologist rec Mir my son has no symptoms and also mri needs sedation is it dermal sinus ex fro X-ray my son has very very tiny are open or closed I can not say it is very lower in back about 2 cm or more above anal area what should do know should we go for further evaluation