--in the US at least, though it has been around for about 20 years as a test, magnetic resonance neurography (which is basically a specialized MRI tuned/focused to look very specifically at nerves) is still considered an experimental test in most quarters here, meaning it won't be paid for by insurance (and it's not cheap).

I've talked about this test with various radiologists, and not all of them are familiar with it, either; apparently it takes very specialized training to interpret the results of MRN's. (I had tried to pursue this when my pudendal symptoms were flaring up, but couldn't get my insurance company to even acknowledge this existed. I had to send them articles and such about it. Their "experts" don't seem to know anything regarding it, though, so no chance of getting it paid for.)