Diffusion tensor imaging with quantitative evaluation and fiber tractography of lumbar nerve roots in sciatica

•In the present study, we first elected ROIs corresponding to the proximal, medial, and distal levels of the lumbar foraminal zone.•The ROC analysis for FA values of distal nerves indicated a high level of reliability in the diagnosis of sciatica.•The declining trend of FA values from proximal to distal along the nerve tract may correlate with the disparity of axonal regeneration at different levels.•DTI is able to quantitatively evaluate compressed nerve roots and has a higher sensitivity and specificity for diagnosing sciatica than conventional MR imaging.•DTT enables visualization of abnormal nerve tracts, providing vivid anatomic information and probable localization of nerve compression.

ObjectiveTo quantitatively evaluate nerve roots by measuring fractional anisotropy (FA) values in healthy volunteers and sciatica patients, visualize nerve roots by tractography, and compare the diagnostic efficacy between conventional magnetic resonance imaging (MRI) and DTI.Materials and methodsSeventy-five sciatica patients and thirty-six healthy volunteers underwent MR imaging using DTI. FA values for L5–S1 lumbar nerve roots were calculated at three levels from DTI images. Tractography was performed on L3–S1 nerve roots. ROC analysis was performed for FA values.ResultsThe lumbar nerve roots were visualized and FA values were calculated in all subjects. FA values decreased in compressed nerve roots and declined from proximal to distal along the compressed nerve tracts. Mean FA values were more sensitive and specific than MR imaging for differentiating compressed nerve roots, especially in the far lateral zone at distal nerves.ConclusionsDTI can quantitatively evaluate compressed nerve roots, and DTT enables visualization of abnormal nerve tracts, providing vivid anatomic information and localization of probable nerve compression. DTI has great potential utility for evaluating lumbar nerve compression in sciatica.