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Background and Purpose: As in adult imaging, FLAIR can be applied to pediatric brain imaging, and this requires an appreciation of the normal pediatric brain appearance by FLAIR imaging. The purpose of this study was to describe the MR appearance of the brain in normal infants and young children as demonstrated by fluid-attenuated inversion-recovery (FLAIR) MR imaging., Methods: We retrospectively examined MR brain studies, interpreted as normal by pediatric radiologists, from 29 patients (aged 1 to 42 months) to catalog the appearance of myelination in multiple brain areas., Results: On T2-weighted images, white matter progressed from hyperintense to hypointense relative to adjacent gray matter over the first 2 years of life. An analogous, although slightly delayed sequence was observed on FLAIR images with the exception of the deep cerebral hemispheric white matter, which followed a triphasic sequence of development. On FLAIR images, the deep cerebral white matter was heterogeneously hypointense relative to gray matter in the young infant, became hyperintense early in the first few months of life, and then reverted to hypointense during the second year of life., Conclusion: The normal appearance and development of brain white matter must be taken into account when interpreting FLAIR images of infants and young children.

Thin (5-mm) coronal high-field (1.5-T) MR images of four human brain specimens and 14 normal volunteers were correlated with myelin-stained microtomic sections of the specimen cerebella. The primary white-matter tracts innervating several hemispheric (posterior quadrangular, superior, and inferior semilunar, gracile, biventer, tonsil) and vermian (declive, folium, tuber) lobules are oriented perpendicularly to the coronal plane of section and are shown well on proton-density-weighted (long TR/short TE) and T2-weighted (long TR/long TE) spin-echo images, which provide excellent contrast between gray and white matter. Several of the surface sulci and fissures of the cerebellar hemispheres (including the superior posterior, horizontal, secondary, and posterolateral fissures) also course perpendicular to the coronal plane and are depicted well on T1-weighted (short TR/short TE) and T2-weighted images, which maximize contrast between CSF and parenchyma. The opportunity for side-to-side comparison of the hemispheres is a distinct advantage of the coronal view. Nevertheless, more obliquely oriented surfaces (preculminate, primary, inferior posterior, inferior anterior, and intrabiventral fissures) and deep hemispheric structures (primary white-matter tracts to central, anterior quadrangular, and floccular lobules) may be obscured by volume-averaging in the coronal plane; moreover, much of the finer anatomy of the vermis is depicted poorly. The constant surface and deep anatomy of the cerebellum revealed on coronal images in normal volunteers encourages detailed mapping. MR imaging in the coronal plane should be especially useful in identifying, localizing, and quantifying normal and abnormal morphologic differences between the cerebellar hemispheres.