ABSTRACT
Objective To explore the characteristics of diffusion weighted imaging (DWI) of lumbar sacral nerve roots (LSNR)in normal and degenerative lumbosacral vertebrae. Methods The research recruited 20 normal volunteers and 31 patients with spinal stenosis on conventional MRI and DWI scans in lumbosacral spine. We measured the areas from lumbar 3 to sacral 1 at the intervertebral spaces and reconstructed the 3D maximum intensity projection (MIP) and counted the apparent diffusion coefficient (ADC)of LSNR and ganglions. Results In the control group, 196 (98%) LSNR ran symmetrically and lateroinferiorly and 200 ganglions were well defined on MIP of DWI. In the patients group, 74 LSNR showed changes of compression on both T1WI and T2WI, in which DWI appeared thin and distorted in 59 (80%). The ADC value of LSNR were(1.70 ± 0.40)× 10-3 mm2/s and(1.98 ± 0.57) × 10-3 mm2/s separately in normal volunteers and patients (P=0.000), while the ADC values of ganglions were(1.42 ± 0.21)× 10-3 mm2/s and (1.54 ± 0.53)× 10-3 mm2/s respectively in normal volunteers and patients (P=0.000). Conclusion DWI can display the pattern and course of LSNR and ganglions, which indicate that ADC values of compressed LSNR and ganglions are higher than normal ones.
ABSTRACT
Objective To make sciatic nerve traction injury models of rabbit , in order to prospectively evaluate possibility and accuracy of diffusion tensor tracking (DTT) in sciatic nerve injures. Methods The right sciatic nerves of 32 New Zealand white rabbits were selected for traction injury , and the left sciatic nerves were the sham operation side. DTI scan was performed before and after the operation on 1st day , 3rd day, and 1 week, 2, 3, 4, 6 and 8th week respectively, and DTT was reconstructed. Then the length of reconstructed fiber tracts and fiber density index were calculated. After the MRI scan , the sciatic nerve was removed to perform pathologic examination at different time points. Results The difference of the length of reconstructed fiber tracts between nerve traction injury and sham operation side was significant at 1 day~2weeks after operation (P<0.05), while the difference was not significant at 3~8 weeks.The fiber density index of nerve traction injury and sham operation side was significantly different at 1 day~8 weeks(P<0.05). 1day after operation, myelin sheath of traction portion was obviously twisting. 3 days after operation , a large amount of myelin sheath broke down. 2 weeks after operation , axon, myelin sheath degeneration and regeneration coexisted at the same time. 8 weeks after operation , nerve fibers regenerated and restored to normal structure. Conclusion The length time curve and density index-time curve of nerve traction injury are consistent with the changes of pathology , which can be used as a supplementary method to evaluate the degeneration and regeneration in nerve injury.