Comparison of susceptibility values in deep gray matter nuclei between the tremor-dominant (TD) and postural instability and gait disorder (PIGD) groups and healthy controls (HCs). **, P<0.01; *, P<0.05. CN, caudate nucleus; DN, dentate nucleus; GP, globus pallidus; PU, putamen; RN, red nucleus; SNc, substantia nigra pars compacta; SNr, substantia nigra pars reticulata.