Neuroradiology can be either a one or two year fellowship after a 5 year diagnostic radiology residency. Most people do one year these days because the job market is so good. None of the radiology fellowships are very hard to get into these days and many great neuroradiology fellowships have not even filled recently.
As for what you do when you get out of fellowship, I must again discuss the two options: Private vs Academic. In most private practice radiology groups, fellowship trained rads do a certain percentage of their fellowship topic and the rest is general stuff. So you may do neuro half the time, but the other half is x-rays, body CTs, etc. The reason for this is that most private hospitals don't have the volume to have dedicated neurorads. The pay is generally not much different that radiology without fellowship (200K-300K to start, 250K-500K for partners in a few years) (this is true of most rads fellowships except VIR, which is slightly higher average). However, fellowship will help get a better job in bigger cities.
Academic neurorads do only neuro, including MRI, CT, and neuroangiography (so they get some procedures too). Neurorads are usually some of the more research oriented people in radiology and there is a lot of cool stuff being done right now. Income is less than private (100K-200K to start, slower increase).
These are all general ideas that I got from searching internet radiology job sites and from my experience at academic and private hospitals as a med student. I am sure there are exceptions to everything said above. I'm thinking about neuroradiology as a field, so I've done quite a bit of research into it.
