Contrast is not strictly necessary for an MS diagnosis if there are older lesions that the T2 sequence can pick up, the gadolinium highlights active lesions...however I'm pretty sure every single one of us will have stories of missed lesions and tests not done the way they should be, so there's no excuse not to be thorough. I am an MRI coordinator at a major hospital and our MS protocol always includes contrast unless the patient is allergic.

I feel so bad for you guys in the US with the way your health insurance stuff works