Unless the physicians he is going to are of a completely different order than almost any that I (or you) have run into.

So, yes, they are not routine .

Miller's?

One can only hope!

Of course the medical status of DJT is suspicious but it is not definitive to pin that on having an MRI.

MRI exams are usually ordered for a specific issue but they are also available as a boutique service for anxious people who stay up at night stewing on some hidden asymptomatic anomaly.
[link:prenuvo.com] "Go beyond the traditional checkups"... "Helping empower your total health journey"...
"Our most comprehensive whole body MRI screening that checks for hundreds conditions across most major organs — helping you catch health issues early, often before symptoms appear"…
Available for the well-healed, well-concerned person.
So they might be useful for a high-value executive. A president is easily a person who could merit having such a high level screening.
Yes, you, too, can have your own MRI screening for the low cost of $$$$$$$ even if you feel completely well. CALL NOW!!!

Trump is obviously not completely well and his MRI was likely indicated for a real organic illness.

But let us turn our attention back to Trump's many other symptoms and behaviors to predict his imminent demise, BUT having an MRI is not necessarily evidence of that.