Comparing diffusion tensor and spherical harmonic tractography for in utero studies of fetal brain connectivity

摘要

Techniques for iterative reconstruction of magnetic resonance diffusion images from motion corrected multi-planar acquisitions are beginning to allow the use of more complex diffusion models and tractography techniques to study early brain connectivity. Many techniques have been developed for adult and neonatal brain tractography from diffusion images. However, fundamental differences in the underlying tissues, signal levels and relative spatial resolution that are available in fetal studies mean these techniques may need to be significantly adapted to deal with the different challenges. Here we evaluate and compare the use of diffusion tensor and spherical harmonic models in extracting known fetal white matter connective anatomy from multi-planar, motion corrected, variable data density studies of normally developing human fetal brains. Visual evaluation of known tracts indicates that, although there are significant differences in the diffusion properties of fetal brain tracts and also image signal strength in fetal brain studies, when compared to adult brain imaging and tractography, high order models such as spherical harmonic techniques still offer advantages in appropriately delineating known anatomy from in utero data.