Two different doors
A hospital MRI booked through your insurer needs a referral. That referral is what makes it insured care. A private clinic can often book you with no letter, because you are paying the clinic directly.
What you give up without a letter
- Reimbursement from basic insurance, in almost all cases.
- A doctor who already knows which protocol fits your symptoms. The clinic can still choose a sensible protocol, but it is working from what you tell them.
If you already have a referral, take it even to a private clinic. It tells the radiologist what question to answer, and you can still ask your insurer whether any of the cost qualifies. Self-pay without a letter is allowed at many clinics. It is not the same as a covered hospital appointment.