AbstractObjectiveThis study aimed to explore the correlation between T1 and T2 relaxation times of synthetic MRI (SyMRI) and gestational age (GA) in each hemisphere of preterm and term newborns at the initial 28 days of birth.MethodsSeventy preterm and full‐term infants were prospectively included in this study. All subjects completed 3.0 T routine MRI and SyMRI (MAGiC) one‐stop scanning within 28 days of birth (aged 34–42 W at examination). The SyMRI postprocessing software (v8.0.4) was used to measure the T1 and T2 relaxation values of each brain region. The linear regression equations of quantitative relaxation values with GA were established to compare the variation speed in each brain region.ResultsA significant linear and negative correlation was found between relaxation times and GA in the neonate cerebral cortex and subcortical gray and white matter regions (Allp<.05). The relaxation time of the left centrum semiovale decreased with maximum variance with increasing GA among all white matter regions (T1:b= –51.45,β= –0.65,p< .0001; T2:b= –8.77,β= –0.71,p< .0001), whereas the right posterior limb of internal capsule showed minimal variance (T1:b= –27.94,β= –0.60,p< .0001; T2:b= –3.25,β= –0.68,p< .0001). Among all gray matter regions, the right globus pallidus and thalamus indicated the most significant decreasing degree of T1 and T2 relaxation values with GA (right globus pallidus T1:b= –33.14,β= –0.64,p< .0001; right thalamus T2:b= –3.94,β= –0.81,p< .0001), and the right and left occipital lobes indicated the least significant decreasing degree of T1 and T2 relaxation values with GA, respectively (right occipital lobes T1:b= –11.18,β= –0.26,p= .028; left occipital lobes T2:b= –1.22,β= –0.27,p= .024).ConclusionsSyMRI could quantitatively evaluate the linear changes of T1 and T2 relaxation values with GA in brain gray and white matter of preterm and term neonates.