Altered gray-to-white matter tissue contrast in preterm-born adults

Abstract

Aims: To investigate cortical organization in brain magnetic resonance imaging (MRI) of preterm-born adults using percent contrast of gray-to-white matter signal intensities (GWPC), which is an in vivo proxy measure for cortical microstructure.

Methods: Using structural MRI, we analyzed GWPC at different percentile fractions across the cortex (0%, 10%, 20%, 30%, 40%, 50%, and 60%) in a large and prospectively collected cohort of 86 very preterm-born (<32 weeks of gestation and/or birth weight <1500 g, VP/VLBW) adults and 103 full-term controls at 26 years of age. Cognitive performance was assessed by full-scale intelligence quotient (IQ) using the Wechsler Adult Intelligence Scale.

Results: GWPC was significantly decreased in VP/VLBW adults in frontal, parietal, and temporal associative cortices, predominantly in the right hemisphere. Differences were pronounced at 20%, 30%, and 40%, hence, in middle cortical layers. GWPC was significantly increased in right paracentral lobule in VP/VLBW adults. GWPC in frontal and temporal cortices was positively correlated with birth weight, and negatively with duration of ventilation (p < 0.05). Furthermore, GWPC in right paracentral lobule was negatively correlated with IQ (p < 0.05).

Conclusions: Widespread aberrant gray-to-white matter contrast suggests lastingly altered cortical microstructure after preterm birth, mainly in middle cortical layers, with differential effects on associative and primary cortices.

Keywords: brain development; cerebral cortex; preterm birth; structural magnetic resonance imaging; tissue contrast.

FIGURE 1

Group comparison of GWPC at 10%, 20%, 30%, 40%, and 50% projection fractions. All ROIs in which ComBat‐harmonized values of GWPC were significantly different in VP/VLBW individuals compared to FT controls. Statistical significance was defined as p < 0.05, FDR‐corrected. P‐values are color‐coded, darker colors indicate lower p‐values. Both hemispheres are shown in medial and lateral views. FT, full‐term; GWPC, gray‐to‐white matter percentage contrast; VP/VLBW, very preterm and/or very low birth weight.

FIGURE 2

Relationship between GWPC and birth variables. (A) Scatter plots showing significant (p < 0.05) results of partial correlation analyses between GWPC and BW for GWPC in VP/VLBW<FT. BW (in grams) is plotted on the x‐axes and GWPC is plotted on the y‐axes. (B) Scatter plots showing significant (p < 0.05) results of partial correlation analyses between GWPC and duration of ventilation for GWPC in VP/VLBW<FT. Duration of ventilation (in days) is plotted on the x‐axes and GWPC is plotted on the y‐axes. Linear regression lines as well as correlation coefficients and p‐values were added. Bold letters indicate statistical significance defined as p < 0.05. Asterisks (*) indicate statistical significance defined as p < 0.05, FDR‐corrected. BW, birth weight; GWPC, gray‐to‐white matter percentage contrast

FIGURE 3

Relationship between GWPC and cognitive performance. Scatter plots showing significant (p < 0.05) results of partial correlation analyses between GWPC and full‐scale IQ for GWPC in VP/VLBW>FT. GWPC is plotted on the x‐axes and full‐scale IQ is plotted on the Y‐axes. GWPC, gray‐to‐white matter percentage contrast.