CT Scan Retroactively Denied By Insurance

I am writing to ask for your help regarding a recent insurance denial for a CT scan that was already completed at Mayo Clinic.My insurance provider (Highmark, through eviCore) retroactively denied coverage for:

CPT 73220 – CT scan of the right arm without contrast
CPT 76376 – 3D rendering/3D imaging

The denial letter stated that the request did not include enough clinical details to show why the CT scan was medically necessary. Because of this, both the scan and 3D images were denied, even though the procedure has already been performed.

I am very worried about being held responsible for the cost of this test, as I trusted that it was medically necessary and ordered appropriately by my Mayo Clinic provider. I even went to the business office prior to getting the CT scan to ask if it would be covered. I am still experiencing symptoms in my right hand/arm and am continuing to get treatment for my issues, and the CT was an important step in my care.

I've reached out to my provider with this information and the billing office for help, but haven't gotten any useful information as of yet. I also email the patient experience office.

Can any of you suggest what more I can do? The scan is over $2100!