Diffusion tensor magnetic resonance imaging and fiber tractography of the sacral plexusin children with spina bifida

Purpose It is still largely unknown how neural tube defects in spina bifida affect the nerves at the level of the sacral plexus. Visualizing the sacral plexus in 3 dimensions could improve our anatomical understanding of neurological problems in patients with spina bifida. We investigated anatomical and microstructural properties of the sacral plexus of patients with spina bifida using diffusion tensor imaging and fiber tractography. Materials and Methods Ten patients 8 to 16 years old with spina bifida underwent diffusion tensor imaging on a 3 Tesla magnetic resonance imaging system. Anatomical 3-dimensional reconstructions were obtained of the sacral plexus of the 10 patients. Fiber tractography was performed with a diffusion magnetic resonance imaging toolbox to determine fractional anisotropy, and mean, axial and radial diffusivity in the sacral plexus of the patients. Results were compared to 10 healthy controls. Results Nerves of patients with spina bifida showed asymmetry and disorganization to a large extent compared to those of healthy controls. Especially at the myelomeningocele level it was difficult to find a connection with the cauda equina. Mean, axial and radial diffusivity values at S1-S3 were significantly lower in patients. Conclusions To our knowledge this 3 Tesla magnetic resonance imaging study showed for the first time sacral plexus asymmetry and disorganization in 10 patients with spina bifida using diffusion tensor imaging and fiber tractography. The observed difference in diffusion values indicates that these methods may be used to identify nerve abnormalities. We expect that this technique could provide a valuable contribution to better analysis and understanding of the problems of patients with spina bifida in the future. Key Words urinary bladder; spinal dysraphism; lumbosacral plexus; diffusion tensor imaging; diagnostic imaging Abbreviations and Acronyms 3D, 3-dimensional; AD, axial diffusivity; DTI, diffusion tensor imaging; FA, fractional anisotropy; FT, fiber tractography; MD, mean diffusivity; MRI, magnetic resonance imaging; RD, radial diffusivity; ROI, region of interest; SB, spina bifida; TSE, turbo spin-echo