Our daughter had two hemangiomas on the side of her head behind either ear. They were about the same size as Millie's. When she was about 6 weeks old, our doctor ordered an ultrasound on her head to ensure that there weren't any internally-and there weren't. I guess they weren't worried about the possibility of any inside her torso area since they just scanned her head.
We did the wait and see approach until she was about 10 months old and then we started her on propranolol. The medicine helped a lot-I only wish we had started it sooner. One of the hemangiomas had gotten so big we did get it removed because her skin was overstretched. I don't know for sure, but I assume that had we started propranolol while her hemangioma was growing we could have avoided it getting so big and therefore avoided surgery. I have not had this thought confirmed by a doctor, but it's my personal thought on it.
At any rate, she's 19 months now. Her surgery was a month ago to remove the larger of her two hemangiomas. We chose to leave the smaller one since it's pretty well covered by her hair, and her skin is not as overstretched there. She's doing fabulous, and her scar is healing beautifully!