Comparison Of MR Neurography Of The Sacral Plexus And Sciatic Nerve With Unenhanced And Enhanced 3D STIR SPACE Sequence With Comparative Study On DTI Between Healthy Volunteers And Patients With Tethered Cord Syndrome

Part ? Comparison of MR neurography of the sacral plexus and sciatic nerve with unenhanced and enhanced 3D STIR SPACE sequenceObjective: To compare advantages and disadvantages of unenhanced and enhanced 3D STIR(short inversion recovery) SPACE(sampling perfection with application-optimized contrasts using different flip angle evolutions) sequence in the anatomy visualization of sacral plexus and sciatic nerve.Methods: 27 patients underwent unenhanced and enhanced 3D STIR SPACE sequence and were evaluated the visualization of sacral plexus and sciatic nerve. The coronal MIP reconstruction images of bilateral lumbar 4 ~ sacral 4 and sciatic nerve were observed. According to the display of nerve continuity, boundary and fascicles shape, scores from 1 to 4 were evaluated by the quantitative clarity of the nerve in images.Results: Bilateral lumbar 4 ~ sacral 4 and sciatic nerve have 378 nerves in all. The scores from 1 to 4 using unenhanced 3D STIR SPACE sequence were 25.1%(95/378), 59.0%(223/378), 15.9%(60/378) and 0%(0/378), respectively. The scores from 1 to 4 using enhanced 3D STIR SPACE sequence were 20.9%(79/378), 20.9%(111/378), 39.4%(149/378) and 10.3%(39/378), respectively. Each of lumbar 4 ~ sacral 4 and sciatic nerve had 54 nerves. The display rate(higher than 2 points) using the unenhanced 3D STIR SPACE sequence were 94.4%(51/54), 96.3%(52/54), 98.1%(53/54), 100%(54/54), 77.8%(42/54), 20.4%(11/54) and 37.0%(20/54), respectively. The display rate using the enhanced 3D STIR SPACE sequence were100%(54/54), 98.1%(53/54), 98.1%(53/54), 100%(54/54), 77.8%(42/54), 35.2%(19/54) and 44.4%(24/54), respectively. The enhanced images in 3D STIR SPACE sequence were better than the unenhanced images. And the difference is statistically significant(P <0.05).Conclusions: The unenhanced and enhanced 3D STIR SPACE sequence can both clearly display sacral plexus and sciatic nerve. And the enhanced is better than the unenhanced. Part ? Comparative study on DTI between healthy volunteers and patients with tethered cord syndromeObjective: To quantitatively analyze, compare the fractional anisotropy(FA) and apparent diffusion coefficient(ADC) of the sacral plexus L4 ~ S3 nerve and observe the architectural configuration of the sacral plexus by using diffusion tensor imaging(DTI) and fiber tractography on 25 volunteers and 6 patients with tethered cord syndrome(TCS) at 3.0 Tesla MR imaging.Methods: 25 healthy volunteers and 6 patients with tethered cord syndrome underwent 3D STIR SPACE sequence and DTI EPI sequence scan, transport Tensor imaging of EPI sequence to the Neuro 3D workstation, place ROI in L4 ~ S3 nerve root to acquire FA and ADC. Then transport 3D STIR SPACE sequence to the Neuro 3D workstation for fusion, after parameter setting, reconstruct the fiber pathways by seeding and observe the architectural configuration of the sacral plexus.Result: There is no significant difference in FA or AD between the left and right side at the L4 ~ S3 levels in 25 volunteers and 6 patients(P >0.05). Furthermore, no significant difference was found between individual nerves per level(P >0.05). However, significantly lower mean FA was found in patients than in controls at the L5 ~ S2 levels(P =0.034, 0.034, 0.005). DTI and fiber tractography allows for 3D insights in the normal anatomy and general organization of the sacral plexus, and patients with abnormal configurations.Conclusion: Diffusion tensor imaging and fiber tractography applied to the patients with tethered cord syndrome, able to observe the sacral plexus nerve microstructural properties changes and abnormal architectural configuration.