The Clinical And Experimental Study Of Diffusion Tensor Imaging In The Spinal Cord With Compression Of Cervical Spinal Cord

Objective1.The Diffusion Tensor Imaging(DTI)of the cervical spinal cord and lumbosacral enlargement in volunteers and cervical spondylotic myelopathy(CSM)patients was performed on a 1.5 T magnetic resonance imaging(MRI)system.We aimed to observe the changes of DTI parameters of the cervical spinal cord and lumbosacral enlargement in patients with spondylotic myelopathy,and to discuss their correlation.2.To observe the changes of DTI parameters of the lumbosacral enlargement in the rat model of chronic cervical spinal cord compression at different time points,and to discuss their correlation with the DTI parameters of the cervical spinal cord compressed.3.By observing the behavior and histopatholoy of the rat model,we aimed to discuss the characteristics of histopathology at the reginal and distal site of the injured spinal cord and its relation with hind limb motor function.Method1.10 patients diagnosed with cervical spondylotic myelopathy and with high signal on conventinal MRI were included as test group,and 10 age-matched healthy volunteers were included as control group.Apparent diffusion coefficient(ADC)and fractional aniostropy(FA)values of the cervical spinal cord from C2/3 to C6/7 and lumbosacral enlargement were measured in the two groups.We compared ADC nad FA values of different segments in volunteers.ADC and FA values of the cervical and Lumbosacral enlargement in the two groups were also compared respectively.ADC and FA values of the cervical spinal cord were correlated with those of the lumbosacral enlargement in the two groups respectively.2.50 Rats were randomized into five groups according to different treatment factors:control group(group A),sham group(group B),and test groups(1 week,2 weeks and3 weeks;group C,D and E),with 10 rats in each group.All MRI and DTI studies were carried out 1 week,2 weeks and 3 weeks post-operatively at the site of compressed cervical spinal cord and lumboascral enlargement of the spinal cord.ADC and FA values of different groups were compared and the correlation of DTI parameters between lumboascral enlargement and the compressed cervical spinal cord was analyzed.3.Another 50 Rats were randomized into five groups according to different treatment factors:control group(group A),sham group(group B),and test groups(1 week,2weeks and 3 weeks;group C,D and E),with 10 rats in each group.Assessing the hind limb motor function by BBB scores.By HE staining and MBP immunohistochemical staining,we assessed the histopathological changes of the nerve fiber bundle at the reginal and distal site of the injured spinal cord and lumbosacral enlargement of the spinal cord.Histopathological changes of the axons were observed by NF-200 antibody staining.The difference of mean optical density(MOD)at MBP and NF-200 staining regions between the cervical spinal cord and lumbosacral enlargement was compared.Results1.Differences of ADC and FA values were not significant between different cervical segments in the control group,and no correlation was found between the cervical spinal cord and the lumbosacral enlargement.ADC value of the cervical spinal cord and the lumbosacral enlargement in the CSM group showed significant increase while FA value showed decrease compared with the control group.ADC and FA values of the cervical spinal cord had no correlation with those of the lumbosacral enlargement in CSM group.2.No significant differences of ADC and FA values were found between different cervical segments in normal adult female SD rats.The average ADC and FA value of the cervical spinal cord was(1.428±0.199)×10^-3mm²/s and 0.501±0.111 respectively.At the compressed cervical spinal cord,ADC increased and FA decreased with time,especially in group D.ADC value of the cervical spinal cord in group D had a significant correlation with that of the lumbosacral enlargement.3.All rats had a BBB score of 21 before surgery.No symptoms of spinal cord compression were found in group A and B.BBB scores in the test group at different time points(1d,3d and 5d postoperatively)showed no significant differences(P>0.05).BBB score started to decrease at 1 week postoperatively,and the difference was increasing until 3 weeks postoperatively.Results of HE staining showed that no spinal cord injury was found in group A and B.Morphological structure of group C,D and E showed obvious changes and the changes aggravated with time.Results of MBP immunohistochemical staining and NF-200 antibody staining showed that in the test group,positive staining was lighter and the areas were unevenly distributed compared with those in the control group and the sham group.Demyelinated nerve fibres and axonal loss phenomenon in the test group were more obvious and aggravated with time.Conclusion1.Changes of DTI parameters can be used to quantify the changes of microstructures of the cervical spinal cord and lumbosacral enlargement in CSM patients.ADC value of the cervical spinal cord and lumbosacral enlargement in CSM patients showed significant increase compared with healthy volunteers,while FA value showed significant decrease.The ADC and FA value of the cervical spinal cord in CSM patients had no linear correlation with those of the lumbosacral enlargement.2.After chronic compression of the cervical spinal cord in rats,changes of ADC and FA value can be used to quantify the changes of microstructures of the spinal cord at different time points,and the ADC value of the cervical spinal cord had a significant linear correlation with that of the lumbosacral enlargement.3.Obvious changes were found in morphological structures of the cervical spinal cord and the lumbosacral enlargement spinal cord and aggravated with time.Chronic compression of the cervical spinal cord in rats led to pathological changes in the nerve fiber bundle of the lumbosacral spinal cord,which was in accordance with the changes of motion function.