I need to write a introduction letter from administration to referring md's regarding new start up for mri services in their area.

I am not sure about the relationship between you and your target audience and the topic of the introduction letter. Are you connected to the mri service provider or the doctors?

In the meantime, a question about introduction letters was answered in the past with some resources that may help you. I have included the link to the previous question below.

https://www.askmehelpdesk.com/writin...ion-66858.html