Delayed early developmental trajectories of white matter tracts of functional pathways in preterm-born infants: Longitudinal diffusion tensor imaging data

Probabilistic maps of white matter pathways related to motor, somatosensory, auditory, visual, and limbic functions, and major white matter tracts (the corpus callosum, the inferior fronto-occipital fasciculus, and the middle cerebellar peduncle) were applied to evaluate the developmental trajectories of these tracts, using longitudinal diffusion tensor imaging (DTI) obtained in term-born and preterm-born healthy infants. Nineteen term-born and 30 preterm-born infants completed MR scans at three time points: Time-point 1, 41.6±2.7 postmenstrual weeks; Time-point 2, 46.0±2.9 postmenstrual weeks; and Time-point 3, 50.8±3.7 postmenstrual weeks. The DTI-derived scalar values (fractional anisotropy, eigenvalues, and radial diffusivity) of the three time points are available in this Data article.


Subject area
Biology More specific subject area

Developmental Medicine, Neonatology
Type of data The diffusion tensor was calculated using DtiStudio. Each image was transformed to the JHU-neonate atlas using dual-channel large deformation diffeomorphic metric mapping.

Experimental features
DTIs of 19 term-born and 30 preterm-born healthy infants were acquired at three time points. Data source location Queen's Medical Center, University of Hawaii, Honolulu, Hawaii, USA Data accessibility Data is within this article.

Value of the data
The data demonstrated in this paper can be used as a reference for future research related to early brain development.
The dataset from healthy term-born infants can be used as a control for future disease-oriented studies.
The data can be used a benchmark to evaluate other image analysis methods.

Experimental design
The probabilistic maps of pathways related to motor, somatosensory, auditory, visual, and limbic functions, and major white matter tracts (the corpus callosum, the inferior fronto-occipital fasciculus, and the middle cerebellar peduncle) [1] (freely downloadable from (http://cmrm.med.jhmi.edu/)) were applied to evaluate the developmental trajectories of these tracts, using longitudinal diffusion tensor imaging obtained in term-born and preterm-born infants. The FA, e0, e1, e2, and radial diffusivity were measured at each time point.  Table 2 Corrected first eigenvalues (e0) of each time point and the difference between term-and preterm-born groups. Results are sorted by the group effect from lower to higher p-value.  Table 3 Corrected second eigenvalues (e1) of each time point and the difference between term-and preterm-born groups. Results are sorted by the group effect from lower to higher p-value.  Table 4 Corrected third eigenvalues (e2) of each time point and the difference between term-and preterm-born groups. Results are sorted by the group effect from lower to higher p-value.  Table 5 Corrected radial diffusivity values of each time point and the difference between term-and preterm-born groups. Results are sorted by the group effect from lower to higher p-value.

Participants
Eighty-four term-born and preterm-born infants were enrolled. The infants' parents or legal guardians first provided written and verbal informed consent for the study, which was approved by the Co-operative Institutional Review Board of the Queen's Medical Center, the University of Hawaii, and the Johns Hopkins University. Nineteen healthy term-born and 30 preterm-born infants completed the longitudinal study and were clinically evaluated by a physician to ensure they fulfilled the study criteria. Maternal exclusion criteria were: 1) Maternal ageo18 years; and 2) Inability to fully understand English, which precluded informed consent. Exclusion criteria for the term-born infants included: 1) Prolonged intensive care (47 days); 2) Intracranial hemorrhage; 3) Neonatal encephalopathy; 4) Known TORCH infection; and 5) Congenital anomaly. Preterm-born infants were excluded if they 1) required supplementary oxygen or mechanical ventilation during the time of scanning; 2) had a circulation, respiratory, or airway abnormality; or 3) were diagnosed with fever, epilepsy, or active infection. These infants also were evaluated with a modified Amiel-Tison Neurological Assessment for newborns, and all had usable MR scans at three time points: Time-point 1, 41.6 72.7 postmenstrual weeks; Time-point 2, 46.0 72.9 postmenstrual weeks; and Time point 3, 50.8 73.7 postmenstrual weeks.

MRI scans
The infants were scanned during natural sleep without sedation. A single-shot echo planer imaging (EPI) acquisition with sensitivity encoding (SENSE) was acquired using a 3T Siemens TIM Trio scanner. The parameters were: matrix, 80 Â 80; field-of-view, 160 Â 160 mm; 2.5 mm thickness; echotime, 106 ms; and repetition time, 7 to 9 s. Diffusion-weighting was applied along 12 independent axes with b¼1000 s/mm 2 , in addition to a minimally diffusion-weighted image.

Application of the probabilistic maps to DTI of term-and preterm-born infants
The average of each of the scalar values (FA, e0, e1, e2, and radial diffusivity) at each white matter pathway, with a probability of more than 75%, was measured for each infant at each time point using the probabilistic maps. For each pathway, a mixed model analysis for repeated measures was performed to investigate chronological changes in the trace values related to brain development over the three time points, and the difference between groups (preterm-born versus term-born groups, and boys versus girls). The infant's age in postmenstrual weeks at the time of the scans was used as a covariate to adjust for variation at each time point. A p-value of 0.05, corrected for multiple comparisons (Bonferroni), was used as the threshold. SPSS Statistics 22 (IBM, Armonk, NY) was used for the statistical analyses. assisted with the data collection and data transfer. We also thank Ms. Mary McAllister for help with manuscript editing, Mr. Rajiv Deshpande for technical support, Dr. Susumu Mori for advice about the DTI scans, and Dr. Doris Lin for image reading and reporting as a neuroradiologist certified by the American Board of Neuroradiology.