Capitalism is based on free markets.

Deviations from free market status in this scenario include:

• The MRI machine is extremely expensive because it’s from a government-enforced patent monopoly
• The insurance is expensive because it’s mandated by government
• The MRI requires a doctor’s prescription because that’s the law

If we had capitalism in medicine, OP would be paying $150 out of pocket to buy an MRI scan from a private company, and that would be that.