Diffusion-weighted imaging in normal fetal brain maturation

Abstract

Diffusion-weighted imaging (DWI) provides information about tissue maturation not seen on conventional magnetic resonance imaging. The aim of this study is to analyze the evolution over time of the apparent diffusion coefficient (ADC) of normal fetal brain in utero. DWI was performed on 78 fetuses, ranging from 23 to 37 gestational weeks (GW). All children showed at follow-up a normal neurological evaluation. ADC values were obtained in the deep white matter (DWM) of the centrum semiovale, the frontal, parietal, occipital and temporal lobe, in the cerebellar hemisphere, the brainstem, the basal ganglia (BG) and the thalamus. Mean ADC values in supratentorial DWM areas (1.68 +/- 0.05 mm(2)/s) were higher compared with the cerebellar hemisphere (1.25 +/- 0.06 mm(2)/s) and lowest in the pons (1.11 +/- 0.05 mm(2)/s). Thalamus and BG showed intermediate values (1.25 +/- 0.04 mm(2)/s). Brainstem, cerebellar hemisphere and thalamus showed a linear negative correlation with gestational age. Supratentorial areas revealed an increase in ADC values, followed by a decrease after the 30th GW. This study provides a normative data set that allows insights in the normal fetal brain maturation in utero, which has not yet been observed in previous studies on premature babies.

Evolution of T1 Relaxation, ADC, and Fractional Anisotropy during Early Brain Maturation: A Serial Imaging Study on Preterm Infants

“…Given fetal diffusion values and maturation curves obtained between 22 and 36 weeks, our findings of ADC and FA values were comparable with the ones presented by different groups, [20][21][22] though subtle differences between fetuses at 37 weeks of gestation and preterm infants at TEA were reported. 23 No fetal data of T1 values are available.…”

High Signal Intensity on T2-Weighted MR Imaging at Term-Equivalent Age in Preterm Infants Does Not Predict 2-Year Neurodevelopmental Outcomes

“…16 The characteristics of T2 signal intensity and diffusion values change with cerebral maturation. 17 Such maturational alterations are visible in both fetal MR imaging 18,19 and in extra uterine preterm infants. 20,21 Thus, another potential explanation for the presence of DEHSI at term-equivalent age is delayed white matter maturation, rather than diffuse injury.…”

Is Brain Maturation Comparable in Fetuses and Premature Neonates at Term Equivalent Age?

“…19,20 Indeed, diffusion parameters in the developing brain have been found to vary with water content, cell density, formation of white matter tracts, membrane potential, and myelination. 3,6,21 Progressive decrease of ADC values in fetuses after 30 weeks GA 3 and in preterm and term neonates 19,20,[22][23][24] has been putatively ascribed to a sequence of events making up the "premyelination stage" 25,26 and the initiation of myelination. Premyelination is a complex process that includes a reduction in total water content, a rise in lipid concentration, the proliferation and maturation of oligodendrocyte precursors, and the ensheathment of axons by premyelin.…”

“…Previous studies of preterm neonates, term neonates, and children have shown correlation between decreased ADC and progressive brain maturation. [1][2][3][4][5] These changes precede those seen on conventional MR images and provide early information on tissue organization. 6 1 H-MR spectroscopy is an efficient technique for obtaining noninvasive metabolic information from the human brain and has become a powerful diagnostic tool in the pediatric population, especially for the detection of hypoxic encephalopathy, leukoencephalopathies, and inborn errors of metabolism.…”