The Study On Diffusion Tensor Imaging Of White Matter Fiber Tracts Of Cervical Cord In Traumatic Cervical Spinal Cord Injury

Spinal Cord Injury(SCI)is usually catastrophic,especially when associated with nerve damage,such as cervical spinal cord paralysis,which is bound to be a heavy burden on the affected families,and increase the financial expenditure of the society and government.Therefore,how to detect SCI early on clinic(especially light,occult SCI),assess the degree of injury and conduct reasonable treatment for the patients with prognosis and rehabilitation is of great significance.Diffusion Tensor Imaging(DTI)is a new imaging technique based on the principle of anisotropic diffusion of water molecules in biological tissues.DTI can better quantitatively analyze the damage of white matter fiber bundles in traumatic SCI patients.DTI can be used within72 hours of SCI to detect cellular edema and axonal damage from a microscopic perspective to assess the integrity of the White Matter Fiber Tracts(WMFT)structure and to quantitatively analyze the extent of myelin injury in WMFT,especially it is of high objectivity and sensitivity in the measurement and evaluation of WMFT microstructure changes of the SCI patients.DTI can detect the micro damages of the WMFT in cervical spinal cord in the hyperacute phase(within 6 hours),particularly it is feasible to detect light,occult SCI after the examination of the CT scan without fracture and the absence of abnormal signals in conventional T1 WI and T2 WI sequences.Therefore,DTI is of highly important value in clinic applications.The purpose of this paper is to study the clinical diagnosis value of DTI in the early detection of SCI by using DTI technique to explore microscopic changes of traumatic SCI patients’ WMFT in different phases of injury,and to providereliable imaging basis for appropriate SCI therapeutic measures and prognosis evaluation.Objective :The changes of WMFT microstructure in SCI patients were observed by3.0T MR diffusion tensor imaging,and the value of DTI in the early diagnosis of SCI was discussed.Methods:34 traumatic SCI inpatients(18 males and 16 females,aged 15-63 years,mean 42.2±12.8 years)and 20 healthy volunteers(10 males and 10 females,aged 15-60 years,mean 38.3±11.5 years)were enrolled in this study.According to the first MR examination and the review time of the patients after trauma,they were divided into three groups.The acute phase group was injured within 72 hours,a total of 34 cases.Subacute group is 72 h ~ 5 weeks,a total of 27 cases.The chronic phase is 5 weeks to 3 months,a total of 17 cases.The patients were scanned with GE 3.0T magnetic resonance,8-channel full-spine phased array coil.MR-DTI technology selected 15 gradient direction,b value of 0,1000s/mm2,from the neck 1 to neck 7 of the continuous scanning.DTI data were transferred to GE AW4.4 workstation and processed by Functool software.The fractional anisotropy(FA)and apparent diffusion coefficient(ADC)were obtained at each level.FA values and ADC values were measured at different levels(11 levels)of healthy volunteers.In the injured group,subjects with high signals in the acute phase T2 WI sequence were divided into positive group(group A)and the most serious level of SCI was measured;subjects without abnormal signals in the T2 WI sequence on the cervical cord were divided into negative group(B group)and the level of vertebral fracture or cervical soft tissue injury was measured.When the patients were reviewed,the measurement level was the same as the first measurement.Three physicians with years of imaging experience worked completely independent on the imaging analysis and data measurement.Results:The maximum FA value in the control group was at C2/3 level and the minimum FA value was at C5 level.The maximum ADC value was at C5 level and the lowest ADC value was at C2/3 level.There was no statistically significant difference between FA and ADC values of different levels of FA value and ADC value between the cervical spinal cord.In the acute phase,the FA value of group A was 0.43 ± 0.37 and the FA value in group B was 0.54 ±0.29.In the subacute phase,the FA value of group A was 0.50 ± 0.29 and the FA value in group B was 0.57 ± 0.21.In the chronic phase,the FA value of group A was 0.56 ± 0.19 and the FA value in group B was 0.61 ± 0.13.Compared with the normal control group,the FA value of group A and group B in the acute phase decreased,and then increased gradually,but it was lower than that of the control group,and the difference was statistically significant(P <0.001).At each time,the FA value of group A was always lower than group B and the difference was statistically significant(P <0.001).In the acute phase,ADC value of group A was(1.31 ± 0.45)× 10-3mm2/s,and ADC value of group B was(1.17 ± 0.33)× 10-3mm2/s.In the subacute phase,the ADC value of group A was(1.26 ± 0.25)× 10-3mm2/s,and the ADC value of group B was(1.07 ± 0.18)× 10-3mm2/s.In the chronic phase,the ADC value of group A was(1.10 ± 0.17)× 10-3mm2/s,and the ADC value of group B was(1.05 ± 0.19)× 10-3mm2/s.Compared with the normal control group,the ADC value of acute group A increased,and then decreased gradually,but it was higher than the control group,and the difference was statistically significant(P <0.001).The ADC value of group B was higher in acute phase(P <0.001),but then gradually became normal,and the difference was not statistically significant(P> 0.05).ADC values in group A were consistently higher than those in group B at all phases.The difference was statistically significant(P <0.001).Conclusion :DTI has a higher sensitivity and specificity for the diagnosis of SCI than conventional MR examinations and can visually display the integrity and thedamages of WMFT.Besides,DTI can determine the severity of SCI and can predict the recovery of cervical spinal cord function.DTI has important clinical value in the diagnosis and treatment of SCI,and it is also significant to the prognosis of SCI.