Diffusion tensor imaging in pediatric spinal cord injury: preliminary examination of reliability and clinical correlation.

STUDY DESIGN

The design was a nonexperimental, repeated measures design.

OBJECTIVE

To examine the reliability of repeated diffusion tensor imaging (DTI) values of the pediatric cord and to compare DTI values with values obtained on the clinical examination and findings from conventional magnetic resonance imaging (MRI).

SUMMARY OF BACKGROUND DATA

DTI quantifies the diffusion of water molecules in directions parallel and transverse to the plane of neuronal axons. The unique characteristic architecture of the spinal cord allows DTI to examine the white matter and potentially separate white matter from gray matter and assess structural damage of the cord.

METHODS

Ten youths with cervical spinal cord injury (SCI) were evaluated using the International Standards for Neurological Classification of SCI (ISNCSCI) and had 2 scans using a 3.0T Siemens Verio MR scanner. The imaging protocol consisted of conventional sagittal fast spin echo T1- and T2-weighted scans, axial fast spin echo T2-weighted scans, and axial DTI acquisition. Intraclass correlation coefficient (ICC) and 95% confidence interval were calculated for mean, axial, and radial diffusivity (MD, AD, RD, respectively) and fractional anisotropy (FA). Relationships among DTI, MRI, and ISNCSCI were evaluated using Spearman correlation coefficients (rs) and differences were tested using Cohen's method.

RESULTS

There was moderate-to-strong reliability (ICC = 0.75-0.95) for MD, AD, and RD for all spinal levels. Reliability for FA for mid-C4 and between C5-C6 and C7-T1 was moderate (ICC = 0.75-0.80). Diffusivity values demonstrated moderate-to-good negative relationships (rs = -0.30 to -0.59), with 4 ISNCSCI values. FA values had a moderate-to-good (rs = 0.33-0.53) positive relationship, with 5 ISNCSCI values. Compared with MRI, DTI values had significantly stronger correlations (P ≤ 0.0001) with the majority of ISNCSCI values.

CONCLUSION

DTI values had good-to-strong reliability on repeated scans and moderate-to-good concurrent validity with clinical scores. When compared with conventional MRI, DTI values had statistically stronger correlations with the majority of values from the clinical examination.