Olivier Ami MD, PhD, Presenter: Nothing to Disclose

Jean-Christophe Maran, Abstract Co-Author: Nothing to Disclose

Dominique MUSSET, Abstract Co-Author: Nothing to Disclose

Diffusion-based cerebral fiber tracking (DTI) is a non-invasive tool often used to describe the three dimensional structure of adult white matter tracts. The goal of this study was to explore and quantify the human developing fetal brain in utero using fiber tracking as a tool to reconstruct and visualize main cerebral fascicules with magnetic resonance imaging, in order to establish an atlas of normal in utero developing anatomy.

30 fetuses between 14 and 41 weeks of gestation planned for medical pregnancy interruption despite normal brain anatomy were enrolled in this study. An first in utero MRI set with DTI acquisition was performed at early morning before the abortion. A second DTI acquisition was performed on the fetuses ex vivo 12 hours after the abortion. A statistical analysis was then performed on the DTI reconstruction stacks. The analysis was done all along each fiber, subject to validation by an expert, from its beginning to its end. A local measure was done on FA value, density of reconstructed tracts and radial eigenvalues and the three dimensional structure of the fiber was sketched. The age-dependent variability was then assessed, and “healthy” and pathological datasets were confronted.

The entire set of ex vivo acquisition was exploitable for quantification. The anatomy has been demonstrated at each stage of development for caudate nucleus, motor and sensorial cortex. Each tract presented forms depending on the gyration stage and the myelination degree of the brain. The density of fibers increased with pregnancy term, reflecting their maturation, due to the reinforcement of the FA during the gestation. The anisotropy decreased with the term of pregnancy. The mean density, FA value and ADC value were specified in a table.

The DTI protocol is feasible to explore fetuses brain in vivo and brings new insights towards early stages of brain development.

Reference tables from this study will serve as comparison bases to help diagnose in utero brain pathologies and quantify the neurological impairment before birth.  

Ami, O, Maran, J, MUSSET, D, High Resolution Diffusion Tensor Imaging and Fiber Tracking of Human Fetal Brain Development from 14 to 41 WG.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14019748.html