WIQL - Get possible values for BoardColumn field

Question

I'm trying to read out all column names in an VSO board and can't figure out how to do this.

I'm using the c# wrapper VisualStudioOnline.Api.Rest and the code:

var fieldInfo = _clientWit.GetField("System.BoardColumn").Result;

This only gives me the following info: Name, ReadOnly, ReferenceName, Type and Url.

I'd like to get the names of all columns.