Not necessarily, if the person running the machine or the person screening the results has to be a trained medical professional. In those cases, due to monopoly and other concerns, we'd have a supply bottleneck which would increase price given increased demands.

I don't however know if you have to be medically trained to use a MRI machine, or interpret the results

One obviously has to be trained to use the MRI machine, and that person is local. But the interpretation is even now not done on site.

Low bandwidth costs mean that it can be done halfway around the world.

You don't need to be a doctor to run an MRI scan, but you do need to be one to interpret the results. In addition, you should really have at least one doctor around to decide exactly what you need to MRI in which way for optimal results for any given clinical problem, as the doctors who ordered the MRI done aren't usually specialists in that area.

In order to have access to an MRI scan you need to have a machine that's geographically close. If the nearest machine is 100 miles away the bar on what will justify a scan goes way up compared to if a machine is an elevator ride away. Buying more machines costs more money.

Increased demand drives costs up, not down.