Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Mar 15;18:784-792.
doi: 10.1016/j.nicl.2018.03.014. eCollection 2018.

Age Related Diffusion and Tractography Changes in Typically Developing Pediatric Cervical and Thoracic Spinal Cord

Affiliations
Free PMC article

Age Related Diffusion and Tractography Changes in Typically Developing Pediatric Cervical and Thoracic Spinal Cord

Mahdi Alizadeh et al. Neuroimage Clin. .
Free PMC article

Abstract

Background and objective: Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) are two techniques that can measure white matter integrity of the spinal cord. Recently, DTI indices have been shown to change with age. The purpose of this study is (a) to evaluate the maturational states of the entire pediatric spinal cord using DTI and DTT indices including fractional anisotropy (FA), mean diffusivity (MD), mean length of white matter fiber tracts and tract density and (b) to analyze the DTI and DTT parameters along the entire spinal cord as a function of spinal cord levels and age.

Method: A total of 23 typically developing (TD) pediatric subjects ranging in age from 6 to 16 years old (11.94 ± 3.26 (mean ± standard deviation), 13 females and 10 males) were recruited, and scanned using 3.0 T MR scanner. Reduced FOV diffusion tensor images were acquired axially in the same anatomical location prescribed for the T2-weighted images to cover the entire spinal cord (C1-mid L1 levels). To mitigate motion induced artifacts, diffusion directional images were aligned with the reference image (b0) using a rigid body registration algorithm performed by in-house software developed in Matlab (MathWorks, Natick, Massachusetts). Diffusion tensor maps (FA and MD) and streamline deterministic tractography were then generated from the motion corrected DTI dataset. DTI and DTT parameters were calculated by using ROIs drawn to encapsulate the whole cord along the entire spinal cord by an independent board certified neuroradiologist. These indices then were compared between two age groups (age group A = 6-11 years (n = 11) and age group B = 12-16 years (n = 12)) based on similar standards and age definitions used for reporting spinal cord injury in the pediatric population. Standard least squared linear regression based on a restricted maximum likelihood (REML) method was used to evaluate the relationship between age and DTI and DTT parameters.

Results: An increase in FA (group A = 0.42 ± 0.097, group B = 0.49 ± 0.116), white matter tract density (group A = 368.01 ± 236.88, group B = 440.13 ± 245.24) and mean length of fiber tracts (group A = 48.16 ± 20.48 mm, group B = 60.28 ± 23.87 mm) and a decrease in MD (group A = 1.06 ± 0.23 × 10-3 mm2/s, group B = 0.82 ± 0.24 × 10-3 mm2/s) were observed with age along the entire spinal cord. Statistically significant increases have been shown in FA (p = 0.004, R2 = 0.57), tract density (p = 0.0004, R2 = 0.58), mean length of fiber tracts (p < 0.001, R2 = 0.5) and a significant decrease has been shown in MD (p = 0.002, R2 = 0.59) between group A and group B. Also, it has been shown DTI and DTT parameters vary along the spinal cord as a function of intervertebral disk and mid-vertebral body level.

Conclusion: This study provides an initial understanding of age related changes of DTI values as well as DTT metrics of the spinal cord. The results show significant differences in DTI and DTT parameters which may result from decreasing water content, myelination of fiber tracts, and the thickening diameter of fiber tracts during the maturation process. Consequently, when quantitative DTI and DTT of the spinal cord is undertaken in the pediatric population an age and level matched normative dataset should be used to accurately interpret the quantitative results.

Keywords: Age; Diffusion tensor imaging; Fiber tractography; Pediatric spinal cord.

Figures

Fig. 1
Fig. 1
Sagittal reconstruction of FA color maps and MD maps of 2 overlapping slabs (A and B). The cervical and middle thoracic regions (A): FA color map (left), MD (middle) and tractography (right). The lower cervical through lower thoracic (B): FA color map (left), MD (middle) and tractography (left). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 2
Fig. 2
Axial color FA, FA, MD and T2W-GRE images for a single subject at different spinal cord levels.
Fig. 3
Fig. 3
An example of ROIs for several positions along the spinal cord.
Fig. 4
Fig. 4
DTI and DTT parameters averaged across all the controls per age groups and plotted as a function of cord levels. The error bars represent the standard deviation.
Fig. 5
Fig. 5
Linear fit plots showing the relationship of FA, MD, Tract Density, and Length of Tract as a function of age in typically developing pediatric subjects. Each point represents the whole cord DTI/DTT measures at each axial slice corresponding to the intervertebral disk level and at axial slice corresponding to the mid-vertebral body level of the cervical and thoracic spinal cord (approximately 40 slices per subject).
Fig. 6
Fig. 6
Size of ROIs manually drown at each intervertebral disk levels and mid-vertebral body levels. The error bars represent the standard deviation.

Similar articles

See all similar articles

Cited by 1 article

References

    1. Alizadeh M., Intintolo A., Middleton D.M., Conklin C.J., Faro S.H., Mulcahey M.J., Mohamed F.B. Reduced FOV diffusion tensor MR imaging and fiber tractography of the pediatric cervical spinal cord. Spinal Cord. 2017;55(3):314–320. - PubMed
    1. Andre J.B., Bammer R. Advanced diffusion-weighted magnetic resonance imaging techniques of the human spinal cord. Top. Magn. Reson. Imaging. 2010;21(6):367–378. - PMC - PubMed
    1. Barakat N., Mohamed F.B., Hunter L.N., Shah P., Faro S.H., Samdani A.F., Finsterbusch J., Betz R., Gaughan J., Mulcahey M.J. Diffusion tensor imaging of the normal pediatric spinal cord using an inner field of view echo planar imaging sequence. AJNR Am. J. Neuroradiol. 2012;33(6):1127–1133. - PubMed
    1. Beaulieu C. The basis of anisotropic water diffusion in the nervous system - a technical review. NMR Biomed. 2002;15:435–455. - PubMed
    1. Berman J.I., Lanza M.R., Blaskey L., Edgar J.C., Roberts T.P. High angular resolution diffusion imaging (HARDI) probabilistic tractography of the auditory radiation. AJNR Am. J. Neuroradiol. 2013;34(8):1573–1578. - PMC - PubMed

Publication types

Feedback