Katherine Leigh Ragland BA, BS, Presenter: Nothing to Disclose

Majid Khan MD, Abstract Co-Author: Nothing to Disclose

Manohar Roda MD, Abstract Co-Author: Nothing to Disclose

Kenneth Liechty MD, Abstract Co-Author: Nothing to Disclose

James Bofill MD, Abstract Co-Author: Nothing to Disclose

Razvan Buciuc MD, Abstract Co-Author: Nothing to Disclose

Judy Rose James PhD, Abstract Co-Author: Nothing to Disclose

Purpose of this study was to assess fetal white matter tract microstructural maturation in utero using Diffusion Tensor MR Imaging (DTI). DTI is a novel imaging modality that utilizes the 3D diffusion patterns of water molecules to aid in microscopic fiber tracking.

An optimized DTI sequence on 1.5T ESPREE (Siemens, Germany) was applied on 11 fetuses with gestational age (GA) ranging from 31–37 weeks as part of the fetal MRI examination. DTI sequence was obtained using axial echo-planar-SE at b=0,800s/mm2 along 12 non co-linear directions; TR/TE=6200/86ms, slice thickness/slice gap=4.0/0.8mm, matrix size=256x256, imaging time=2.08min. Fetuses with structurally normal brains confirmed by ultrasound were analyzed. DTI data was analyzed with DTI-studio (John Hopkins) to generate tensor and ADC maps, perform fiber-tractography, and draw regions of interest (ROI) on bilateral hemispheres. DTI parameters such as fiber count, density, length, fractional anisotropy (FA), trace and radial diffusivity (RD) were averaged for each hemisphere through all the slices. Scatter plots and a linear regression model were used to evaluate relationships between GA and each of the DTI parameters.

A significant improvement in image quality was observed in fetal DTI images, ADC and FA maps with progressing GA.A positive relation was observed between DTI indices and increasing GA. Fiber count showed a rapid increase with brain development (365 fibers at 31 weeks vs. 6140 fibers at 36 weeks; slope=828.1; R2=0.6), followed by fiber length (45mm at 31 weeks vs. 116mm at 36 weeks; slope=12.8, R2=0.4). A linear increase was observed in fiber density with GA (slope=1.14, R2=0.5). Changes in FA, trace, ADC and RD with GA was minimal (mean slope=0.09). Mean FA and ADC at 31 and 36 weeks were as follows: 0.32 vs. 0.41 and 1.4 vs. 1.8 mm2/s respectively.

This study reveals the utility of DTI for evaluating intrauterine conditions. Current data highly suggests that DTI captures microscopic changes in water diffusion properties occurring with brain maturation. Thus, monitoring and evaluating the functional and morphological development of the fetal brain is possible. However, technical improvements and a larger study population are needed to assess the reliability of DTI in evaluating fetal white matter anisotropy development.

DTI can assess in utero maturation changes to fetal cerebral white matter tracts.

Ragland, K, Khan, M, Roda, M, Liechty, K, Bofill, J, Buciuc, R, James, J, Diffusion Tensor Imaging to Evaluate Intrauterine Maturation of Fetal White Matter Tracts.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034295.html