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In vivo examination of white matter integrity after spinal cord injury: a diffusion tensor imaging study 2011

General Spine

Rachael, L, Bosma, BSc.
Christopher, A., Kidd, B.Eng, Non ASSR Member
Patrick, W., Stroman, PhD., Non ASSR Member

Poster

Purpose

Diffusion tensor imaging (DTI) allows for the in vivo examination of the extent of damage to white matter microstructure which may enable the detection and diagnosis of subtle injuries or progressive changes and provide a means of monitoring the effects of therapeutic interventions (1). Despite its clinical potential, there are few studies that use this technique to explore the long-term changes in spinal cord structure after injury (2,3,4). The aim of this study was to characterize DTI indices, including fractional anisotropy (FA) and mean diffusivity (MD), during the chronic stages of spinal cord injury and to compare these indices with those from healthy controls. Furthermore, we aim to determine how anatomical measures relate to preserved function as measured by conventional clinical assessments (ASIA). We hypothesize that changes in diffusivity associated with structural alterations are a sensitive measure of the extent of the lesion and that there will be a strong relationship between structural integrity and sensory and motor function.

Methods & Materials

DTI data were acquired from patients with chronic cervical spinal cord injuries and healthy volunteers. Fractional anisotropy vs. mean diffusivity values were plotted and a k-means clustering method was applied to partition the data into three clusters. Clusters were attributed to white matter, grey matter and CSF. A t test was used to compare FA vs. MD distributions between the regions of the cord.

Results

Mean FA and MD values and ASIA scores are listed in Table 1. Compared to controls, all patients showed significant decreases in both the amount of restricted diffusion and in overall diffusivity, reflected by lower FA values and MD values respectively.

Conclusion

Results from this study further our understanding of the structural damage that results from spinal cord injury and how this damage relates to everyday functioning. These measures may be a valuable supplement to current clinical assessments and may provide greater insight to both physicians and patients in order to guide therapeutic efforts.

References/Financial Disclosures

1. LeBihan et al. Biophysical Journal. 1994; 66: 259-267 2. Shanmuganatha, K. et al. AJNR. 2008; 29: 655-659 3. Ellingson B.M. et al., AJNR. 2008; 29: 1279-1284 4. Ellingson B.M. et al. AJNR. 2008; 29: 1976-1982

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