There are 2 other ways to check, too. Call your doctor's office and find out if they have any problems getting the money from them and/or if they have problems with the company approving the MRIs, etc.
Another way to check is to call your state insurance commissioner's office and find out if there are any complaints about the company...and what the ranking is. Most companies do have complaints but on average do they have a high amount or a low amount of complaints.
I believe every insurance company is set up in regions....may be by state or by sections of the US. How they pay on the east coast may be different than on the west coast.
good luck!