Infant MRI Spine / tethered cord / short lumbar

I really need to find someone who has gone thru this or knows someone who has...

My son has the sacral dimple.

He had 2 ultrasounds. Both showing a short spinal cord.

The 1st time the Dr was relaxed and just said most children are fine.

The 2nd appointment he says to get an MRI to find out why his cord is short.

My son is a totally healthy, thriving young boy.

Hes 3 months right now, he'll be 4 soon.

Is there anyone out there who has ANY experience with this??

Why are we getting an MRI if the Dr doesn't think surgery is needed.... Please calm me down fellow moms... Our appointment isn't until 12/20

His pediatrician said. "Honestly, if you didn't tell me he was seeing an neurosurgeon, i wouldnt have known he had an issue with his cord bc he doesn't have any of the other symptoms"