Medicaid Denied Approval for Scan - Any Suggestions?

I have a dear friend; her 28 year old daughter was diagnosed with breast cancer in November of 2008, exactly one year before me. She completed her chemo, rads and herceptin and had her port removed January of this year and was so very happy to be done with all of this. The last few months she has been having a great deal of pain and experiencing unexplaind weight loss. Her oncologist is very concerned and ordered a PET scan to check for mets. She is on medicaid and medicaid initially denied approval of the scan, then later approved it but has now, just one day before the scheduled scan, has denied it again.

I don't personally have any experience with Medicaid so don't know how to help her. I wanted to reach out to this group on her behalf to see if anyone has had any similar experiences with something like this and if there is any recourse or other options to get her this obviously much needed scan.

I appreciate any feedback or suggestions, feel free to PM me if that works better for you. I'm just shocked that she can't get this scan and terrified that she could have mets and may have to go months with progression until her symptoms worsen enough for Medicaid to approve. 

Thank you in advance to anyone that can offer any suggestions.