Hi OP, I had an MRI as one of many tests for numbness in my hands and feet 2 years ago.
Are you having any other tests (I also had x-ray, ultrasound, CT of head and neck, EMG - electrical tests of nerve function, a lumbar puncture and about 3 gazillion blood tests ok 17 I counted the tubes )
Have they told you what they might be looking for? Or which areas they will be scanning (it was my body from head to hips that was done)?
They can see nerve damage, they can find a reason (and there are hundreds) why you might be losing sensation.
They did with me - mine is a very rare nerve disability only diagnosed 50x/year in the uk. But knowing what it was (and what it wasn't!!) was a huge relief.
Feel free to ask any more or pm me?