title: Radial coherence of diffusion tractography in the cerebral white matter of the human fetus: neuroanatomic insights.
abstract: High angular resolution diffusion imaging (HARDI) demonstrates transient radial coherence of telencephalic white matter in the human fetus. Our objective was to define the neuroanatomic basis of this radial coherence through correlative HARDI- and postmortem tissue analyses. Applying immunomarkers to radial glial fibers (RGFs), axons, and blood vessels in 18 cases (19 gestational weeks to 3 postnatal years), we compared their developmental profiles to HARDI tractography in brains of comparable ages (n = 11). At midgestation, radial coherence corresponded with the presence of RGFs. At 30-31 weeks, the transition from HARDI-defined radial coherence to corticocortical coherence began simultaneously with the transformation of RGFs to astrocytes. By term, both radial coherence and RGFs had disappeared. White matter axons were radial, tangential, and oblique over the second half of gestation, whereas penetrating blood vessels were consistently radial. Thus, radial coherence in the fetal white matter likely reflects a composite of RGFs, penetrating blood vessels, and radial axons of which its transient expression most closely matches that of RGFs. This study provides baseline information for interpreting radial coherence in tractography studies of the preterm brain in the assessment of the encephalopathy of prematurity.
authors.affiliation: Department of Pathology, Children's Hospital Boston, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Gang
authors.initials: G
authors.lastname: Xu
authors.forename: Emi
authors.initials: E
authors.lastname: Takahashi
authors.forename: Rebecca D
authors.initials: RD
authors.lastname: Folkerth
authors.forename: Robin L
authors.initials: RL
authors.lastname: Haynes
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Volpe
authors.forename: P Ellen
authors.initials: PE
authors.lastname: Grant
authors.forename: Hannah C
authors.initials: HC
authors.lastname: Kinney
mesh_terms: D000367:Age Factors; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000196:embryology*; D038524:Diffusion Magnetic Resonance Imaging; D005333:Fetus / Q000033:anatomy & histology*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009413:Nerve Fibers, Myelinated / Q000378:metabolism / Q000502:physiology*; D016900:Neurofilament Proteins / Q000378:metabolism; D009457:Neuroglia / Q000502:physiology; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
chemical_list: D005904:Glial Fibrillary Acidic Protein; C489788:MAP2 protein, human; D008869:Microtubule-Associated Proteins; D016900:Neurofilament Proteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D014746:Vimentin; C051774:neurofilament protein H
keywords: axons; blood vessels; encephalopathy of prematurity; periventricular leukomalacia; radial glial fibers; vimentin