Development of Corpus Callosum in Preterm Infants Is Affected by the Prematurity: In Vivo Assessment of Diffusion Tensor Imaging at Term-Equivalent Age

Abstract

Callosal injury in preterm infants is a key factor affecting neurodevelopmental outcome. We investigated the characteristics of corpus callosum (CC) in preterm infants without apparent white matter lesions. We studied 58 preterm infants divided into three groups of 23-25, 26 -29, and 30 -33 wk GA. Diffusion tensor imaging (DTI) was obtained at term-equivalent age. The CC was parcellated into the genu, body, isthmus, and splenium. We measured fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of each CC subdivision using tractography and manual region of interest analysis. The cross-sectional areas were also measured. At the isthmus and splenium in the 23-25 GA group, the FA was significantly lower and the size was also significantly reduced. Furthermore, the FA and cross-sectional areas in the posterior CC decreased linearly with decreasing GA. There were no differences in FA and cross-sectional areas in other CC subdivisions, and no differences in ADC in any CC subdivisions, among the GA groups. We demonstrated that preterm infants without apparent white matter lesions affect development of the posterior CC depending on the degree of prematurity. (Pediatr Res 69: 249-254, 2011)

Altered Microstructure of White Matter Except the Corpus Callosum Is Independent of Prematurity

“…Multiple regression analysis showed that the FA in the CC increased linearly with the GA at birth. A similar finding was reported by Hasegawa et al [23]; however, de Bruïne et al [24] found no significant maturation trends between the CC and GA at birth. At present, we cannot clearly explain why only the FA of the CC was dependent on GA but not on PMA.…”

“…At present, we cannot clearly explain why only the FA of the CC was dependent on GA but not on PMA. Previous studies reported that younger GA is related to smaller callosal size and altered callosal microstructure in preterm infants and that these are linked to poor neurological outcomes [7,11,23,25]. Impairment of callosal growth is suggested as a potential indicator of cerebral axonal disturbance [1].…”

“…An evaluation of how the changes in the CC will affect neurodevelopment will be explored in a clinical follow-up. We used infants without apparent brain lesions and this may account for the lack of an ADC change in the CC because the ADC in the CC can be altered by WM injury [23]. …”

Comparison of Spin-Echo and Gradient-Echo T1-Weighted and Spin-Echo T2-Weighted Images at 3T in Evaluating Term-Neonatal Myelination

“…27 However, diffusion tensor imaging studies that have focused on the callosal splenium have shown disparate results; 1 study of preterm infants at term-equivalent age found significant differences compared with term infants, while another found no definite relationship between gestational age and changes in various DTI parameters. 28,29 Theoretically, another possibility may relate to a phenomenon called the "visual experience" hypothesis, which essentially states that because preterm infants are "out" of the mother longer by the time of term-equivalent imaging (relative to full-term neonates), healthy premature infants would have experienced a greater degree of visual stimulation and thus would have accelerated maturation of visual pathways by the same postnatal gestational age. 30 Most interesting, studies using visualevoked potentials and contrast sensitivities have suggested accelerated maturation of the visual cortices in preterm relative to term infants, which might have manifested in the current study as earlier visualization of callosal splenium maturation in the preterm infants imaged at term-equivalent age.…”

Abnormal Interhemispheric Connectivity in Neonates with D-Transposition of the Great Arteries Undergoing Cardiopulmonary Bypass Surgery

“…DTI is an MR imaging technique used to characterize the microstructure of large WM tracts in physiologic and pathologic conditions and provides complex measures that reflect various microstructural properties of the WM, including axon diameter, myelination, and fiber attenuation. 17 Microstructural changes in the CC have been described with DTI studies in premature infants, 18 extremely preterm infants, 19 very-low-birth-weight adolescents, 20 and preterm born young adults. 21 The overall aims of this study were to prospectively investigate WM microstructural development in the interhemispheric brain connectivity in neonates with d-TGA before and after CPB.…”