The ability o f near-field High Energy X-ray Diffraction Microscopy (nf-HEDM) to map the dynamic response of microstructures under the influence of thermo-mechanical loads has been repeatedly demonstrated. Here, we use nf-HEDM to monitor the evolution of the same high purity, polycrystalline nickel microstructure through a sequence of five, grain growth anneal states. While the microstructure coarsens in response to the applied heat, the boundary misorientation distribution was found to be both static and consistent with that of a twinned microstructure. Analysis of the E3n grain boundaries shows that in addition to accounting for a large proportion of the grain boundary area, these twin related boundaries also exhibit minimal deviation from the ideal E3n configuration.