Re: will breast MRI show nerve problem in the breast?
It really depends on the nature of the problem. If there is significant demyelination (loss of the fatty insulating sheath around most nerves,) or if there is other significant nerve damage, the MRI is generally considered the best imaging tool. Pinpoint defects (such as minor nerve compression) are often missed in an MRI, as are
many cases of small-fiber neuropathy. This is because MRIs typically cannot detect features smaller than about a millimeter or so. If nothing shows up (i.e. the MRI is "unremarkable," that only means that significant nerve damage was not seen.) If you're being evaluated for a gross demyelinating disease (such as multiple sclerosis,) an unremarkable MRI will not confirm the diagnosis, but at least it will serve as a baseline against which future MRIs can be compared for evidence of disease progression.
I don't know if that helps you much, but if you care to elaborate on your symptoms, history, and diagnoses being discussed, I (and others here) may be able to give you more useful information.