A Diffusion Tensor Imaging Study to Compare Normative Fractional Anisotropy Values at the Lumbar Spine with Patients Suffering From Low Back Pain

Abstract

Background: Backache radiating to the limbs is the most common cause for nerve root compression which can lead to several functional abnormalities. Magnetic resonance imaging (MRI) provides valuable information regarding the size, shape, location and impact of disc herniation on the nerve root fibres, so MRI is used in the diagnosis of the disc herniation but inconsistencies were seen between the clinical symptoms and MRI findings. Diffusion tensor imaging (DTI) of lumbar nerve root fibres reduces the number of false positive and false negative findings and thus increases the concordance between clinical and imaging findings. Fractional anisotropy (FA) values ranges from 0 and 1 which describes the degree of anisotropy of a diffusion process. The current study explored the difference in FA values between subjects suffering from with and without low back pain using DTI.

Materials and Methods: 45 patients with low backache and 45 controls were employed to evaluate changes of the lumbar spine using DTI derived FA values. A Philips Achieva 1.5 Tesla MRI unit was used for data collection. In the present study we evaluated both FA and Apparent Diffusion Co-efficient (ADC) values in six regions of the lumbar spine.

Results: Patients with low backache showed differences in FA values compared to control group. Descriptive data analysis was done using SPSS software version 20.0. However the values did not follow normal distribution so Mann Whitney U test was used to correlate FA and ADC values in both the groups. Significant differences were found in FA at both sides of the L4 vertebrae. We also found significant differences in ADC at the left side of L3 and right side of the L4 vertebrae.

Conclusion: : Our findings indicate that DTI and FA can be used in patients with low backache for early detection and treatment. The affected side of the spine showing symptoms of the nerve roots showed significant reduction in FA and slight increase in ADC values.