Rong Xue PhD, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: To understand the three-dimensional (3D) changes in the shape and organization of human fetal brain structures during development based on the diffusion tensor imaging (DTI) contrast. Compared to conventional MRI, DTI provides better contrasts in delineating details of different brain compartments at early fetal stages. Methods and Materials: Three formalin-fixed normal human fetal brains (17.5, 19.9 and 22 gestational weeks) were imaged with single-loop surface coils. Experiments were performed on a GE 4.7T (200MHz) Omega spectrometer. A 3D multiple spin-echo (SE) DTI sequence was accomplished to acquire diffusion-weighted (DW) images with weighting applied along at least 6 independent axes. The b-value of the maximal DW image was 3.3x10 5 sec/cm2. The minimal DW image has a b value of 6.0x104 sec/cm2. With a TR of 0.9s, NEX of 2, one DW image took 2 hours and 20 min including the data storage time. In this study, four T2-weighted images were also obtained with TEs of 37ms, 70ms, 100ms, and 120ms respectively. Results: A series of 2D isotropic DW images, ADC images, FA-vector colormaps and T2 maps of normal human fetal brains are presented. DTI-based contrasts carry detailed anatomical information that cannot be appreciated by the conventional T1 and T2 contrasts. These images show development of cortical plate and white matter tracts during brain maturation. Tracts, such as corpus callosum, internal capsule, anterior commissure, were found early in the 17-week fetal brain. Multiple layers were displayed in the cortical regions. Structures on the MRI images of human brain matched well with the known structures on the human fetal brain atlas. We successfully reconstructed the major 3D white matter fiber tracts at the early fetal stage. In addition, different anatomical structures, such as ventricles, thalamus, caudate-putamen, were segmented based on the DTI contrast. Conclusion: We studied the morphological structures on fixed human fetal brain by comparing T2 and DTI contrasts during development. DTI, which measures the directionality of water diffusion based on the averaged orientation of existing ordered structures, reveals formation of many early neuronal structures. The 3D nature of the dataset is expected to facilitate the characterization of human fetal brain development as well as to study brain developmental disorders, such as the Down¢s syndrome disease.      

Xue PhD, R, Diffusion Tensor Imaging of Ex-Vivo Human Fetal Brain Reveals Anatomical Details during Brain Maturation.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3100040.html