Clinical relevance of diffusion tensor imaging parameters in lumbar disco-radicular conflict

Purpose: To measure the fractional anisotropy (FA) and the mean diffusivity (MD) values of L4, L5 and S1 nerve roots using diffusion tensor imaging (DTI) and to correlate them with four different clinical patterns. Patients and methods: Fifty-six human participants were prospectively included and divided between four groups: healthy subjects, patients with clinical symptomatic nerve root pain with and without anatomical discoradicular conflict and patients with incidental anatomical discoradicular conflict seen on magnetic resonance imaging (MRI). MRI protocol included anatomical sequences (sagittal T1- and T2-weighted, axial T2-weighted) and a 25 directions DTI sequence. FA and MD values were measured in consensus by two readers and compared between the four groups. Results: Mean FA and MD values were significantly different for patients with clinically symptomatic nerve root pain (n = 27) both with (n = 16) (FA = 0.187 +/- 0.015; MD = 510 +/- 40) and without (n = 11) (FA = 0.193 +/- 0.011; MD = 490 +/- 30.5) anatomical discoradicular conflict compared to healthy subjects (n = 29) (FA = 0.221 +/- 0.011; MD = 460.9 +/- 35.5) including 2 subjects with incidental anatomical discoradicular conflict (FA = 0.211 +/- 0.013; MD = 450.8 +/- 41.2) on MRI ( P = 0.003). Conclusion: Measurement of FA and MD values of L4, L5 and S1 nerve roots using DTI could be useful in lumbar nerve root pain assessment. Further studies with different image processing methods are needed. (C) 2013 Editions francaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.