This experiment aims to determine the mechanism triggering the concomitant metal-insulator and antiferromagnet (AF)-paramagnet phase transition taking place in NaOsO3 via three-dimensional (3D) imaging. We will perform Bragg Coherent Diffraction Imaging (BCDI) measurements on both the structural and magnetic peaks to monitor the evolution of both strain and magnetic domains as a function of temperature through the phase transition. By combining BCDI with the dependence of resonant magnetic scattering on the polarization of the incident X-rays, we aim to reconstruct the AF domain structure through the bulk of the sample for the first time. By performing these measurements as a function of temperature through the phase transition, we hope to clarify the role played by magnetostriction in the metal-insulator transition, providing valuable insight into the nature of the phase transition currently under debate.