Supplementary Material for: Cerebrospinal Fluid and Parenchymal Brain Development and Growth in the Healthy Fetus

Objective: The objective of this study was to apply
quantitative magnetic resonance imaging to characterize absolute
cerebrospinal fluid (CSF) development, as well as its relative
development to fetal brain parenchyma in the healthy human fetus. Design:
We created three-dimensional high-resolution reconstructions of the
developing brain for healthy fetuses between 18 and 40 weeks' gestation,
segmented the parenchymal and CSF spaces, and calculated the volumes
for the lateral, third, and fourth ventricles; extra-axial CSF space;
and the cerebrum, cerebellum, and brainstem. From these data, we
constructed normograms of the resulting volumes according to gestational
age and described the relative development of CSF to fetal brain
parenchyma. Results: Each CSF space demonstrated major
increases in volumetric growth during the second half of gestation:
third ventricle (23-fold), extra-axial CSF (11-fold), fourth ventricle
(8-fold), and lateral ventricle (2-fold). Total CSF volume was related
to total brain volume (p < 0.01), as was lateral ventricle to cerebral volume (p < 0.01); however, the fourth ventricle was not related to cerebellar or brainstem volume (p = 0.18-0.19). Relevance:
Abnormalities of the CSF spaces are the most common anomalies of
neurologic development detected on fetal screening using
neurosonography. Normative values of absolute CSF volume, as well as
relative growth in comparison to intracranial parenchyma, provide
valuable insight into normal fetal neurodevelopment. These data may
provide important biomarkers of early deviations from normal growth,
better distinguish between benign variants and early disease, and serve
as reference standards for postnatal growth and development in the
premature infant.