Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.

 

Primarily, tattooing is prohibited in Islam. This is based on the report of Ibn `Umar who said, The Messenger of Allah (peace be upon him) cursed the maker and wearer of a wig and the tattooer and the one who is tattooed. (Al-Bukhari and Muslim)

 

A Muslim can tattoo a part of his body in case it becomes the only medical treatment available for him/her. This is based on report of Abdullah ibn Mas`ud (may Allah be pleased with him) who heard the Prophet (peace be upon him) prohibiting women from plucking hair from their faces, making spaces in between their teeth, making or wearing a wig, the tatooer and the one who is tattooed except for those who have a disease.  (Ahmad)

 

Therefore, if your case of alopecia can be treated through hair transplant, you cannot refer to scalp micopigmentation. If you find no other alternative treatment, you can do it even if it involves tattooing of the head.

 

Allah Almighty knows best.