QSM of brain development and aging. (a) Susceptibility values and contrast evolve as a function of age. Brain nuclei become more paramagnetic (hyperintense) as the age increases. Gray and white matter contrast also increases overall. (b) Susceptibility is diamagnetic in the white matter. It first decreases, becoming more diamagnetic during brain development and maturation, followed by an increase as the brain ages. (c) In the nuclei, susceptibility increases monotonically following an exponential function of age. IC, internal capsule; OR, optical radiation; GP, globus pallidus. The scan parameters are: in-plane resolution = 0.9 × 0.9 mm2, matrix = 256 × 208, flip angle = 20°, TE of first echo = 4.92 msec, echo spacing = 4.92 msec, TR = 35 msec, and number of echoes = 6. The slice thickness is 2 mm.