Diffusion tensor imaging (DTI) is a magnetic resonance imaging technique that allows for the visualization and characterization of the white matter tracts of the brain in vivo. DTI does not assess white matter directly. Rather, it capitalizes on the fact that diffusion is isotropic (equal in all directions) in cerebral spinal fluid and cell bodies but anisotropic (greater in one direction than the other directions) in axons that comprise white matter. It provides quantitative information about the degree and direction of water diffusion within individual units of volume within the magnetic resonance image, and by inference, about the integrity of white matter. Measures from DTI can be applied throughout the brain or to regions of interest. Fiber tract reconstruction, or tractography, creates continuous 3-dimensional tracts by sequentially piecing together estimates of fiber orientation from the direction of diffusion within individual volume units. DTI has increased our understanding of white matter structure and function. DTI shows nonlinear growth of white matter tracts from childhood to adulthood. Delayed maturation of the white matter in the frontal lobes may explain the continued growth of cognitive control into adulthood. Relative to good readers, adults and children who are poor readers have evidence of white matter differences in a specific region of the temporo-parietal lobe, implicating differences in connections among brain regions as a factor in reading disorder. Measures from DTI changed in poor readers who improved their reading skills after intense remediation. DTI documents injury to white matter tracts after prematurity. Measures indicative of white matter injury are associated with motor and cognitive impairment in children born prematurely. Further research on DTI is necessary before it can become a routine clinical procedure. Index Termsdiffusion tensor imaging; magnetic resonance imaging; tractography; children; white matter development; white matter associations with reading disorder; white matter injury in prematurity NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptContemporary neuroscience conceptualizes complex thoughts and emotions as arising from widely distributed and highly interactive neural networks. [1][2][3][4] Localized cortical regions within the gray matter contribute specialized or semispecialized computations to mental activity, functioning like microprocessors. The structure of these regions can be assessed with conventional magnetic resonance imaging. Activity within these regions during cognitive or emotional processing can be assessed using functional magnetic resonance imaging. Axons arising from cell bodies connect neurons to other neurons. Axons are organized into white matter fiber bundles that link cortical regions, acting like cables connecting the microprocessors. Diffusion tensor imaging is an magnetic resonance imaging technique that allows for the visualization and characterization of white matter tracts in living animals and h...

Children born preterm are at risk for deficits in language and reading. They are also at risk for injury to the white matter of the brain. The goal of this study was to determine whether performance in language and reading skills would be associated with white matter properties in children born preterm and full-term. Children born before 36 weeks gestation (n=23, mean±SD age 12.5±2.0 years, gestational age 28.7±2.5 weeks, birth weight 1184±431 g) and controls born after 37 weeks gestation (n=19, 13.1±2.1 years, 39.3±1.0 weeks, 3178±413 g) underwent a battery of language and reading tests. Diffusion Tensor Imaging (DTI) scans were processed using Tract-Based Spatial Statistics to generate a core white matter skeleton that was anatomically comparable across participants. Fractional anisotropy (FA) was the diffusion property used in analyses. In the full-term group, no regions of the whole FA-skeleton were associated with language and reading. In the preterm group, regions of the FA-skeleton were significantly associated with verbal IQ, linguistic processing speed, syntactic comprehension, and decoding. Combined, the regions formed a composite map of 22 clusters on 15 tracts in both hemispheres and in the ventral and dorsal streams. ROI analyses in the preterm group found that several of these regions also showed positive associations with receptive vocabulary, verbal memory, and reading comprehension. Some of the same regions showed weak negative correlations within the full-term group. Exploratory multiple regression in the preterm group found that specific white matter pathways were related to different aspects of language processing and reading, accounting for 27–44% of the variance. The findings suggest that higher performance in language and reading in a group of preterm but not full-term children is associated with higher fractional anisotropy of a bilateral and distributed white matter network.

Background Preterm children are at risk for behavior problems. Studies examining contributions of intellectual and environmental factors to behavior outcomes in preterm children are mixed. Aims (1) To identify the nature of maladaptive behaviors in preterm children age 9 to 16 years born across the spectrum of gestational age and birth weight (BW). (2) To examine contributions of BW as a biological factor, socioeconomic status as an environmental factor, and intelligence quotient (IQ) as indicative of intellectual ability to behavior outcomes. Method Using the Child Behavior Checklist, parent reports of behavior for 63 preterm children (gestational age 24 to < 36 weeks) were compared to 29 full term children of similar age, gender and socioeconomic status. Multiple regression models evaluated effects of prematurity, socioeconomic status, and intellectual ability on behavioral symptom scores. Results Preterm children had higher total and internalizing problem scores compared to full term children. They also had lower IQ. BW was a significant predictor of total and internalizing behavior problems. Among the syndrome scales, anxious/depressed and attention problems were elevated. Socioeconomic status did not contribute to behavior scores. IQ contributed to total, but not to internalizing or externalizing, scores. IQ contributed to attention problems, but not to anxious/depressed scores. Conclusion Preterm children had increased behavior problems, especially symptoms of inattention and anxiety. Lower BW predicted more behavior problems. IQ acted as a mediator between BW and attention scores, but not anxiety scores. These findings alert health care providers to assess anxiety in all preterm children regardless of intellectual ability and to assess attention in those with learning problems. Additional study on the influence of intellectual ability on behavioral outcomes in preterm children is needed.

Although studies of long-term outcomes of children born preterm consistently show low intelligence quotient (IQ) and visual-motor impairment, studies of their performance in language and reading have found inconsistent results. In this study, we examined which specific language and reading skills were associated with prematurity independent of the effects of gender, socioeconomic status (SES), and IQ. Participants from two study sites (N = 100) included 9–16 year old children born before 36 weeks gestation weighing less than 2500 grams (preterm group, n = 65) compared to children born at 37 weeks gestation or more (full-term group, n = 35). Children born preterm had significantly lower scores than full-term controls on Performance IQ, Verbal IQ, receptive and expressive language skills, syntactic comprehension, linguistic processing speed, verbal memory, decoding, and reading comprehension but not on receptive vocabulary. Using MANCOVA, we found that SES, IQ, and prematurity all contributed to the variance in scores on a set of six non-overlapping measures of language and reading. Simple regression analyses found that after controlling for SES and Performance IQ, the degree of prematurity as measured by gestational age group was a significant predictor of linguistic processing speed, β = −.27, p < .05, R2 = .07, verbal memory, β = .31, p < .05, R2 = .09, and reading comprehension, β = .28, p < .05, R2 = .08, but not of receptive vocabulary, syntactic comprehension, or decoding. The language and reading domains where prematurity had a direct effect can be classified as fluid as opposed to crystallized functions and should be monitored in school-age children and adolescents born preterm.

AIM Diffusion tensor imaging (DTI) was used to evaluate white matter architecture after preterm birth. The goals were (1) to compare white matter microstructure in two cohorts of preterm- and term-born children; and (2) within preterm groups, to determine if sex, gestational age, birthweight, white matter injury score from conventional magnetic resonance imaging (MRI), or IQ was associated with DTI measures. METHOD Participants (n=121; 66 females, 55 males) were aged 9 to 16 years. They comprised 58 preterm children (site 1, n=25; and site 2, n=33) born at less than 36 weeks’ gestation (mean 29.4wks; birthweight 1289g) and 63 term children (site 1, n=40; site 2, n=23) born at more than 37 weeks’ gestation. DTI was analyzed using tract-based spatial statistics. Diffusion measures were fractional anisotropy, axial, radial, and mean diffusivity. RESULTS In no region of the white matter skeleton was fractional anisotropy lower in the preterm group at either site. Within the preterm groups, fractional anisotropy was significantly associated with white matter injury score, but not sex, gestational age, or birthweight. At site 1, fractional anisotropy was associated with IQ. INTERPRETATION DTI contributes to understanding individual differences after preterm birth but may not differentiate a relatively high-functioning group of preterm children from a matched group of term-born children.