MRI question

I wonder if someone could give me an answer to the following question,
in the USA how long do people have to wait for an MRI?  I'm guessing
it is different based on your health plan and the HMO  you belong to.

scenario #1    White collar worker in a good plan living in a large
city

secenario #2   single unemployed woman living in a large city

scenario #3    self employed farmer living in the country.


Here in Canada there are waits up to and over a year for a MRI.
Because we have socialized health care everyone waits the same amount
of time, (excepting professional sports players).

thanks in advance.