Clinical Application Research Of Lumbosacral Nerve Root Related Neuropathy By Using Diffusion Tensor Imaging

Objective1. The purpose of this study was to quantitatively evaluate by using diffusion tensor imaging (DTI) and visualize the lumbosacral plexus nerve by diffusion tensor tractography (DTT) in healthy volunteers.2. To quantitatively evaluate L5-S1lumbar 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 Methods1. A total of60healthy volunteers (male30and female30) underwent MR DTI. Mean FA values in the lumbosacral plexus nerve (both side of lumbar roots nerve L3to S1, proximal and distal to the lumbar foraminal zone) were quantified on DTI images. Differences between different segments of lumbar nerve roots were compared with ANOVA test and Student-Newman-Keuls test. Differences between two side of the lumbar nerve roots at the same lumbar segment were compared with paired-samples t test. Differences between the proximal and the distal nerve to the the lumbar foraminal zone at the same lumbar segment were compared with paired-samples t test. The lumbosacral plexus nerve was visualized with tractography.2. Seventy-five unilateral sciatica patients and thirty-six healthy volunteers underwent MR imaging using DTI. FA values for L5-S1lumbar nerve roots were calculated at three levels from DTI images. Tractography was performed on L3-S1nerve roots. ROC analysis was performed for Pfirrmann grade and FA values.Results1.(1) The lumbosacral plexus nerve was clearly visualized with tractography.(2) Mean FA values of the lumbar nerve roots L3to S1:proximal to the left lumbar foraminal zone0.202±0.021,0.201±0.026,0.201±0.027,0.191±0.016, distal to the left lumbar foraminal zone0.222±0.034,0.250±0.028,0.203±0.026,0.183±0.020, proximal to the right lumbar foraminal zone0.200±0.023,0.202±0.023,0.205±0.027,0.191±0.017, distal to the right lumbar foraminal zone0.225±0.032,0.247±0.027,0.205±0.033,0.183±0.021. Mean FA values were significantly different from the proximal nerve to the distal nerve in lumbar nerve roots L3, L4, S1(t=-9.114——2.366, P<0.05), and no significantly different in L5(P>0.05). Differences were not found between the right and left side nerves at the same lumbar segment(P>0.05).(3) Lumbar roots nerve L3to S1can be visualized vividly and completely by using DTT.2. The 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.Conclusion1. Diffusion tensor imaging and tractography can visualize and quantitatively evaluate human lumbosacral plexus nerve. DTI is a potential tool for the diagnosis of lumbosacral plexus nerve disease.2. DTI 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.